EP4734770A1 - Compounds that modulate gprc6a receptor and pet food products containing the same - Google Patents

Abstract

The presently disclosed subject matter relates to compounds and/or flavor compositions for enhancing palatability of pet food products. The presently disclosed subject matter also relates to compounds that modulate the activity of a GPRC6A taste receptor.

Description

069269.0689 PATENT COMPOUNDS THAT MODULATE GPRC6A RECEPTOR AND PET FOOD PRODUCTS CONTAINING THE SAME CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Application No.63/510,968, filed on June 29, 2023, the contents of which are incorporated by reference herein in their entirety and to which priority is claimed. SEQUENCE LISTING The instant application contains a Sequence Listing which has been submitted herewith and is hereby incorporated by reference in its entirety. Said .xml copy, created on June 05, 2024 is named 0692690689.xml, and is 17,754 bytes in size. FIELD The presently disclosed subject matter relates to flavor compositions and/or compounds that interact with a GPRC6A receptor for modulating taste. The flavor compositions and/or compounds can be used to enhance or modify the palatability, taste and/or flavor of pet food products. The flavor compositions can include one or more combinations of compounds and can either be added to pet food products in various delivery system formats or be generated during a manufacturing process of a pet food product. BACKGROUND Taste profiles for edible compositions include basic tastes such as sweet, salt, bitter, sour, umami and kokumi. Taste profiles have also been described as including free fatty acid tastes. Chemical compounds that elicit these tastes are often referred to as tastants. Without being bound by theory, it is hypothesized that tastants are sensed by taste receptors in the mouth and throat which transmit signals to the brain where the tastants and resulting taste profiles are registered. Pet food manufacturers have a long-standing desire to provide pet food products that have high nutritional value. In addition, and with particular regard to cat and dog foods, pet food manufacturers desire a high degree of palatability so that pets can receive the full nutritional benefit from their food. Domestic animals are notoriously finicky in their food preferences and often refuse to eat a pet food product that it has accepted over time or refuse to eat any more than a minimal amount of a pet food product. This phenomenon can be, in part, due to the subtle differences in the sensory profiles of the raw material, which can be perceived by the domestic animals because of their gustatory and olfactory systems. As a result, pet owners frequently Active 118427983.2 1 069269.0689 PATENT change types and brands of pet food in order to maintain their pets in a healthy and contented condition. While there have been recent advances in taste and flavor technologies, there remains a need for compounds that can enhance or modify the palatability of pet food products by enhancing or modifying the taste, texture and/or flavor profiles of the pet food product. The enhancement or modification can be to increase the intensity of a desirable attribute, to replace a desirable attribute not present or somehow lost in the pet food product, or to decrease the intensity of an undesirable attribute. In particular, it is desirable to increase the intensity of a desirable tastant in a pet food product. Therefore, there remains a need in the art for compositions to enhance the palatability and/or modulate the kokumi taste of pet food products. SUMMARY OF THE INVENTION In certain embodiments, the present disclosure relates to a pet food product including: (a) one or more compounds that bind to a GPRC6A receptor or a functional fragment thereof; or (b) a flavor composition including one or more compounds that bind to a GPRC6A receptor or a functional fragment thereof. In certain embodiments, the pet food product has enhanced palatability. In certain embodiments, the one or more compound increases, decreases or modulates the biological activity of the GPRC6A receptor. In certain embodiments, the one or more compound is selected from the group consisting of amino acids, peptides, hormones, ions, metals, butanoic acid-based compounds, propanoic acid-based compounds, pentanoic acid-based compounds, carboxylic acid- based compounds, derivatives thereof, and combinations thereof. In certain embodiments, the one or more compound has an EC50 value of no more than about 50 mM in connection with a biological activity of the GPRC6A receptor. In certain embodiments, the compound has the formula: . In certain embodiments, R1 is selected from the group selected from the group consisting of H, C₁-C₂₀ alkyl, branched C₁-C₂₀ alkyl, unbranched C₁-C₂₀ alkyl, C₁-C₂₀ alkenyl, brached C₁- C₂₀ alkenyl, unbranched C₁-C₂₀ alkenyl, C₁-C₂₀ alkynyl, branched C₁-C₂₀ alkynyl, unbranched C₁- C20 alkynyl, arylalkyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, heteroarylalkyl, haloalkyl, CF3, halogen, phenyl, -C(O)R₃, -COOR₃, -NR₃R₄, -NO₂, -OH, -OR₃, -CONR₃R₄, -S-Aryl, -O-Aryl, - N-Aryl, -NO₂, -SO₃H, -SO₂R₃, -NHOH, -C=CR₃, -C=NOH, -OP(O)(OH)₂, and CHO. In certain Active 118427983.2 2 069269.0689 PATENT embodiments, R3 and R4 are each independently selected from the group consisting of H, C1-C20 alkyl, branched C₁-C₂₀ alkyl, unbranched C₁-C₂₀ alkyl, C₁-C₂₀ alkenyl, brached C₁-C₂₀ alkenyl, unbranched C₁-C₂₀ alkenyl, C₁-C₂₀ alkynyl, branched C₁-C₂₀ alkynyl, unbranched C₁-C₂₀ alkynyl, arylalkyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, heteroarylalkyl, haloalkyl, CF3, and halogen. In certina embodiments, R1 is substituted. In certain embodiments, R₂ is selected from the group consisting of H, C₁-C₂₀ alkyl, branched C1-C20 alkyl, unbranched C1-C20 alkyl, C1-C20 alkenyl, brached C1-C20 alkenyl, unbranched C1-C20 alkenyl, C1-C20 alkynyl, branched C1-C20 alkynyl, unbranched C1-C20 alkynyl, arylalkyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, and heteroarylalkyl. In certain embodiments, R2 is H or methyl. In certain embodiments, the compound has the formula: . In certain embodiments, R is selected from the group consisting of H, C1-C20 alkyl, branched C1-C20 alkyl, unbranched C1-C20 alkyl, C1-C20 alkenyl, brached C1-C20 alkenyl, unbranched C₁-C₂₀ alkenyl, C₁-C₂₀ alkynyl, branched C₁-C₂₀ alkynyl, unbranched C₁-C₂₀ alkynyl, arylalkyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, heteroarylalkyl, haloalkyl, CF₃, halogen, phenyl, -C(O)R3, -COOR3, -NR3R4, -NO2, -OH, -OR3, -CONR3R4, -S-Aryl, -O-Aryl, -N-Aryl, - NO₂, -SO₃H, -SO₂R₃, -NHOH, -C=CR₃, -C=NOH, -OP(O)(OH)₂, and CHO. In certain embodiments, R₁ and R₂ are each independently selected from the group consisting of H, C₁-C₂₀ alkyl, branched C1-C20 alkyl, unbranched C1-C20 alkyl, C1-C20 alkenyl, brached C1-C20 alkenyl, unbranched C₁-C₂₀ alkenyl, C₁-C₂₀ alkynyl, branched C₁-C₂₀ alkynyl, unbranched C₁-C₂₀ alkynyl, arylalkyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, heteroarylalkyl, haloalkyl, CF₃, and halogen. In certain embodiments, R is substituted. In certain embodiments, the compound includes: (a) includes an L-amino-acid; (b) includes one carbon after the ^^-carbon of the amino-acid unit; (c) can include a positively-charged group at a distance up to ~9A from the ^^-carbon (alpha carbon denoting the carbon of the compound to the amino group to the carboxyl group); and/or (d) does not include a negatively- charged group at a distance up to ~9A from ^^-carbon. In certain embodiments, the one or more compound is present at a concentration of between about 0.0001% and about 2% weight/weight (w/w) in the pet food product. In certain embodiments, the flavor composition is present at a concentration of between about 0.0001% and about 2% weight/weight (w/w) in the pet food product. In certain embodiments, the one or more Active 118427983.2 3 069269.0689 PATENT compound is present at a concentration of between about 0.00001% and about 5% in the flavor composition. In certain embodiments, the GPRC6A receptor is a feline GPRC6A receptor. In certain embodiments, the GPRC6A receptor is a canine GPRC6A receptor. In certain embodiments, the presently disclosed subject matter relates to a method for increasing palatability of a pet food product, the method including providing a pet food product; and (a) admixing the pet food product with at least one compound that binds to one or more amino acids of a GPRC6A receptor; or (b) admixing the pet food product with at least one flavor composition, wherein the flavor composition includes a compound that binds to one or more amino acids of a GPRC6A receptor. In certain embodiments, the at least one compound is selected from the group consisting of amino acids, peptides, hormones, ions, metals, butanoic acid-based compounds, propanoic acid-based compounds, pentanoic acid-based compounds, carboxylic acid-based compounds, derivates thereof, and combinations thereof. In certain embodiments, the compound has the formula: . In certain embodiments, R1 is selected from the group selected from the group consisting of H, C₁-C₂₀ alkyl, branched C₁-C₂₀ alkyl, unbranched C₁-C₂₀ alkyl, C₁-C₂₀ alkenyl, brached C₁- C20 alkenyl, unbranched C1-C20 alkenyl, C1-C20 alkynyl, branched C1-C20 alkynyl, unbranched C1- C20 alkynyl, arylalkyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, heteroarylalkyl, haloalkyl, CF3, halogen, phenyl, -C(O)R₃, -COOR₃, -NR₃R₄, -NO₂, -OH, -OR₃, -CONR₃R₄, -S-Aryl, -O-Aryl, - N-Aryl, -NO2, -SO3H, -SO2R3, -NHOH, -C=CR3, -C=NOH, -OP(O)(OH)2, and CHO. In certain embodiments, R3 and R4 are each independently selected from the group consisting of H, C1-C20 alkyl, branched C₁-C₂₀ alkyl, unbranched C₁-C₂₀ alkyl, C₁-C₂₀ alkenyl, brached C₁-C₂₀ alkenyl, unbranched C₁-C₂₀ alkenyl, C₁-C₂₀ alkynyl, branched C₁-C₂₀ alkynyl, unbranched C₁-C₂₀ alkynyl, arylalkyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, heteroarylalkyl, haloalkyl, CF3, and halogen. In certina embodiments, R1 is substituted. In certain embodiments, R₂ is selected from the group consisting of H, C₁-C₂₀ alkyl, branched C1-C20 alkyl, unbranched C1-C20 alkyl, C1-C20 alkenyl, brached C1-C20 alkenyl, unbranched C1-C20 alkenyl, C1-C20 alkynyl, branched C1-C20 alkynyl, unbranched C1-C20 alkynyl, arylalkyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, and heteroarylalkyl. In certain embodiments, R2 is H or methyl. Active 118427983.2 4 069269.0689 PATENT In certain embodiments, the compound has the formula: . In certain embodiments, R is selected from the group consisting of H, C1-C20 alkyl, branched C1-C20 alkyl, unbranched C1-C20 alkyl, C1-C20 alkenyl, brached C1-C20 alkenyl, unbranched C₁-C₂₀ alkenyl, C₁-C₂₀ alkynyl, branched C₁-C₂₀ alkynyl, unbranched C₁-C₂₀ alkynyl, arylalkyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, heteroarylalkyl, haloalkyl, CF₃, halogen, phenyl, -C(O)R3, -COOR3, -NR3R4, -NO2, -OH, -OR3, -CONR3R4, -S-Aryl, -O-Aryl, -N-Aryl, - NO₂, -SO₃H, -SO₂R₃, -NHOH, -C=CR₃, -C=NOH, -OP(O)(OH)₂, and CHO. In certain embodiments, R₁ and R₂ are each independently selected from the group consisting of H, C₁-C₂₀ alkyl, branched C1-C20 alkyl, unbranched C1-C20 alkyl, C1-C20 alkenyl, brached C1-C20 alkenyl, unbranched C₁-C₂₀ alkenyl, C₁-C₂₀ alkynyl, branched C₁-C₂₀ alkynyl, unbranched C₁-C₂₀ alkynyl, arylalkyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, heteroarylalkyl, haloalkyl, CF₃, and halogen. In certain embodiments, R is substituted. In certain embodiments, the compound includes: (a) includes an L-amino-acid; (b) includes one carbon after the ^^-carbon of the amino-acid unit; (c) can include a positively-charged group at a distance up to ~9A from the ^^-carbon (alpha carbon denoting the carbon of the compound to the amino group to the carboxyl group); and/or (d) does not include a negatively- charged group at a distance up to ~9A from ^^-carbon. In certain embodiments, the at least one compound binds to one or more amino acids of a Venus Flytrap Domain of the GPRC6A receptor. In certain embodiments, the least one compound binds to one or more amino acids of a 7-transmembrane domain of the GPRC6A receptor. In certain embodiments, the GPRC6A receptor is a feline GPRC6A. In certain embodiments, the at least one compound binds to one or more amino acids of the feline GPRC6A receptor selected from the group consisting of Tyr148, Ser149, Glu170, Thr172, Asp 218, Tyr220, Arg279, Asp303, Asn304, Thr307, Arg399, Asn400, and combination thereof. In certain embodiments, the compound binds to one or more amino acids of the feline GPRC6A receptor selected from the group consisting of Arg662, Gln663, Phe666, Gly667, Phe670, Gln715, Glu746, Ala751, Phe752, Met755, Leu756, Ile759, Tyr793, Trp797, Phe800, Tyr804, Glu816, Val819, Ile820, and combinations thereof. In certain embodiments, the GPRC6A receptor is a canine GPRC6A. In certain embodiments, the at least one compound binds to one or more amino acids of the canine GPRC6A receptor selected from the group consisting of Tyr148, Ser149, Glu170, Thr172, Asp 218, Tyr220, Active 118427983.2 5 069269.0689 PATENT Arg279, Asp303, Asn304, Met307, Arg399, Asn400, and combination thereof. In certain embodiments, the compound binds to one or more amino acids of the GPRC6A receptor selected from the group consisting of Arg662, Gln663, Phe666, Gly667, Phe670, Gln715, Glu746, Ala751, Phe752, Met755, Leu756, Ile759, Tyr793, Trp797, Phe800, Tyr804, Glu816, Val819, Ile820, and combinations thereof. In certain embodiments, the at least one compound is present at a concentration of between about 0.0001% and about 2% in the pet food product. In certain embodiments, the flavor composition is present at a concentration of between about 0.001% and about 2% in the pet food product. In certain embodiments, the at least one compound is present at a concentration of between about 0.00001% and about 5% in the flavor composition. In certain embodiments, the method includes thermal processing of a food product precursor, wherein the compound is generated during the thermal processing. BRIEF DESCRIPTION OF THE DRAWINGS Figures 1A-1D show responses of fGPRC6A expressing and non-expressing cells towards L-Arginine and Carbachol in the presence of increasing DMSO concentrations (0%, 0.5%, 1.0%, 1.5%). Figures 2A and 2B show responses of fGPRC6A expressing cells to L-Arginine and MgCl2. The different ligands have been co-applied. Figures 3A-3F show representative examples of agonistic activity of compounds incubated with fGPRC6A expressing and non-expressing cells. Figures 4A-C show an example of a standard amino acid in the VFT of fGPRC6A. Figure 4A shows the motif of the GPRC6A ligand binding pharmacophore. Figure 4B shows the closed conformation of the VFT with lysine. Figure 4C shows a closeup of a lysine in the VFT. The ligand makes an interaction to the hinge area of the VFT (SER149, THR172, ASP303, TYR220). Electrostatic interaction between zwitterionic nitrogen and ASP303 and hydrophobic interaction with TYR220 occur. Negatively charged GLU170 makes the electrostatic interaction with the charged nitrogen of the Lysine. Hydrogen bonds are shown are shown in dashed lines. Figures 5A-C show an example of a non-standard amino acid in the VFT of fGPRC6A. Figure 5A shows the structure of Nω-Nitro-L-arginine. Figure 5B shows the closed conformation of the Flytrap with Nω-Nitro-L-arginine. Figure 5C shows that the ligand makes an interaction to the hinge area of the VFT (SER149, THR172, ASP303, TYR220). Electrostatic interaction between zwitterionic nitrogen and ASP303, hydrophobic interaction with TYR220, salt bridge of nitro group with ARG399 and salt bridges with GLU170 and ASP303 occur. Hydrogen bonds are shown in dashed lines. Active 118427983.2 6 069269.0689 PATENT DETAILED DESCRIPTION To date, there remains a need for a compound and/or flavor composition that can provide a desired level of enhanced and targeted palatability of various pet food products. The present application relates to compounds and/or flavor compositions that can be used to increase the palatability and/or enhance or modify the taste of various food products such as a nutritionally- complete pet food. In certain embodiments, the compounds and/or flavor compositions can be used to increase the kokumi taste of a pet food product. The flavor compositions can further include combinations of compounds, including amino acids, and can be added to pet food products in various delivery system formats. 1. Definitions The terms used in this specification generally have their ordinary meanings in the art, within the context of this invention and in the specific context where each term is used. Certain terms are discussed below, or elsewhere in the specification, to provide additional guidance to the practitioner in describing the methods and compositions of the invention and how to make and use them. As used herein, the use of the word “a” or “an” when used in conjunction with the term “comprising” in the claims and/or the specification can mean “one,” but it is also consistent with the meaning of “one or more,” “at least one,” and “one or more than one.” The term “about” or “approximately” means within an acceptable error range for the particular value as determined by one of ordinary skill in the art, which will depend in part on how the value is measured or determined, i.e., the limitations of the measurement system. For example, “about” can mean within 3 or more than 3 standard deviations, per the practice in the art. Alternatively, “about” can mean a range of up to 20%, preferably up to 10%, more preferably up to 5%, and more preferably still up to 1% of a given value. Alternatively, particularly with respect to biological systems or processes, the term can mean within an order of magnitude, preferably within 5-fold, and more preferably within 2-fold, of a value. The terms “comprise(s),” “include(s),” “having,” “has,” “can,” “contain(s),” and variants thereof, as used herein, are intended to be open-ended transitional phrases, terms, or words that do not preclude the possibility of additional acts or structures. The present disclosure also contemplates other embodiments “comprising,” “consisting of”, and “consisting essentially of,” the embodiments or elements presented herein, whether explicitly set forth or not. As used herein, “taste” refers to a sensation caused by activation of receptor cells in a subject’s taste buds. In certain embodiments, taste can be selected from the group consisting of Active 118427983.2 7 069269.0689 PATENT sweet, sour, salt, bitter, kokumi and umami. In certain embodiments, “taste” can include free fatty acid taste. See, e.g., Cartoni et al., J. of Neuroscience, 30(25): 8376-8382 (2010), the contents of which are incorporated herein by reference. In certain embodiments, a taste is elicited in a subject by a “tastant.” In certain embodiments, a tastant can be a synthetic tastant. In certain embodiments, the tastant is obtained or prepared from a natural source. As used herein, “taste profile” refers to a combination of tastes, such as, for example, one or more of a sweet, sour, salt, bitter, umami, kokumi and free fatty acid taste. In certain embodiments, a taste profile is produced by one or more tastant that is present in a composition at the same or different concentrations. In certain embodiments, a taste profile refers to the intensity of a taste or combination of tastes, for example, a sweet, sour, salt, bitter, umami, kokumi and free fatty acid taste, as detected by a subject or any assay known in the art. In certain embodiments, modifying, changing or varying the combination of tastants in a taste profile can change the sensory experience of a subject. As used herein, “flavor” refers to one or more sensory stimuli, such as, for example, one or more of taste (gustatory), smell (olfactory), touch (tactile) and temperature (thermal) stimuli. In certain non-limiting embodiments, the sensory experience of a subject exposed to a flavor can be classified as a characteristic experience for the particular flavor. For example, a flavor can be identified by the subject as being, but not limited to, a floral, citrus, berry, nutty, caramel, chocolate, peppery, smoky, cheesy, meaty, etc., flavor. As used herein, a flavor composition can be selected from a liquid, solution, dry powder, spray, paste, suspension and any combination thereof. The flavor can be a natural composition, an artificial composition, a nature identical, or any combination thereof. As used herein, “flavor profile” refers to a combination of sensory stimuli, for example, tastes, such as sweet, sour, bitter, salty, umami, kokumi and free fatty acid tastes, and/or olfactory, tactile and/or thermal stimuli. In certain embodiments, the flavor profile comprises one or more flavors which contribute to the sensory experience of a subject. In certain embodiments, modifying, changing or varying the combination of stimuli in a flavor profile can change the sensory experience of a subject. As used herein “admixing,” for example, “admixing the flavor composition or combinations thereof of the present application with a food product” or “admixing the compound with a food product,” refers to the process where the flavor composition, or individual components of the flavor composition, is mixed with or added to the completed product or mixed with some or all of the components of the product during product formation or some combination of these steps. When used in the context of admixing, the term “product” refers to the product or any of its components. This admixing step can include a process selected from the step of adding the Active 118427983.2 8 069269.0689 PATENT flavor composition to the product, spraying the flavor composition on the product, coating the flavor composition on the product, suspending the product in the flavor composition, painting the flavor composition on the product, pasting the flavor composition on the product, encapsulating the product with the flavor composition, mixing the flavor composition with the product and any combination thereof. The flavor composition can be a solution, liquid, dry powder, spray, paste, suspension and any combination thereof. In certain embodiments, the compounds can be generated during the thermal processing of a pet food product, e.g., sterilization, retorting, injection molding and/or extrusion, from precursor compounds present in the pet food product. In certain embodiments, a compound can be generated during the processing of a pet food product and additional components of the flavor composition, e.g., a nucleotide and/or an amino acid, can be added to the pet food product by admixing. As used herein, “ppm” means parts-per-million and is a weight relative parameter. A part- per-million is a microgram per gram, such that a component that is present at 10 ppm is present at 10 micrograms of the specific component per 1 gram of the aggregate mixture. As used herein, “palatability” can refer to the overall willingness of a human or non-human animal, for example, a companion animal, to eat a certain food product. Increasing the “palatability” of a food product can lead to an increase in the enjoyment and acceptance of the food by the human or non-human animal to ensure the human or non-human animal eats a “healthy amount” of the food. Decreasing the “palatability” of a food product can lead to a decrease in the enjoyment and acceptance of the food by the human or non-human animal. The term “healthy amount” of a food as used herein refers to an amount that enables the human or non-human animal to maintain or achieve an intake contributing to its overall general health in terms of micronutrients, macronutrients and calories, for example, such as set out in the “Mars Petcare Essential Nutrient Standards.” In certain embodiments, “palatability” can mean a relative preference of a human or non-human animal for one food product over another. For example, when a human or non-human animal shows a preference for one of two or more food products, the preferred food product is more “palatable,” and has “enhanced palatability.” In certain embodiments, the relative palatability of one food product compared to one or more other food products can be determined, for example, in side-by-side, free-choice comparisons, e.g., by relative consumption of the food products, or other appropriate measures of preference indicative of palatability. Palatability can be determined by a standard testing protocol in which the animal has equal access to both food products such as a test called “two-bowl test” or “versus test.” Such preference can arise from any of the animal’s senses, but can be related to, inter alia, taste, aftertaste, smell, mouth feel and/or texture. Active 118427983.2 9 069269.0689 PATENT The term “pet food” or “pet food product” or “final pet food product” means a product or composition that is intended for consumption by a companion animal, such as cats, dogs, guinea pigs, rabbits, birds and horses. For example, but not by way of limitation, the companion animal can be a “domestic” dog, e.g., Canis lupus familiaris. In certain embodiments, the companion animal can be a “domestic” cat such as Felis domesticus. A “pet food” or “pet food product” includes any food, feed, snack, food supplement, liquid, beverage, treat, toy (chewable and/or consumable toys), meal substitute or meal replacement. As used herein “nutritionally-complete” refers to pet food product that contains all known required nutrients for the intended recipient of the pet food product, in appropriate amounts and proportions based, for example, on recommendations of recognized or competent authorities in the field of companion animal nutrition. Such foods are therefore capable of serving as a sole source of dietary intake to maintain life, without the addition of supplemental nutritional sources. As used herein “flavor composition” refers to at least one compound or biologically acceptable salt thereof that modulates, including enhancing, multiplying, potentiating, decreasing, suppressing, or inducing, the tastes, smells, flavors and/or textures of a natural or synthetic tastant, flavoring agent, taste profile, flavor profile and/or texture profile in an animal or a human. In certain embodiments, the flavor composition comprises a combination of compounds or biologically acceptable salts thereof. In certain embodiments, the flavor composition includes one or more excipients. As used herein, the terms “modulates” or “modifies” refers to an increase or decrease in the amount, quality or effect of a particular activity of a receptor and/or an increase or decrease in the expression, activity or function of a receptor. “Modulators,” as used herein, refer to any inhibitory or activating compounds identified using in silico, in vitro and/or in vivo assays for, e.g., agonists, antagonists, allosteric modulators and their homologs, including fragments, variants and mimetics. “Inhibitors” or “antagonists,” as used herein, refer to modulating compounds that reduce, decrease, block, prevent, delay activation, inactivate, desensitize or down regulate the biological activity and/or expression of a receptor or pathway of interest. The term “antagonist” includes full, partial, and neutral antagonists as well as inverse agonists. “Inducers,” “activators” or “agonists,” as used herein, refer to modulating compounds that increase, induce, stimulate, open, activate, facilitate, enhance activation, sensitize or upregulate a receptor or pathway of interest. The term “agonist” includes full and partial agonists. “Allosteric modulators” as used herein, refer to “positive allosteric modulators” and “negative allosteric modulators.” “Positive allosteric modulators” (also known as “PAM”) refer to modulating compounds that increase, induce, stimulate, open, activate, facilitate, enhance Active 118427983.2 10 069269.0689 PATENT activation, sensitize or up regulate a receptor or pathway of interest caused by the binding of a different compound to the receptor. “Negative allosteric modulators” refer to modulating compounds that reduce, decrease, block, prevent, delay activation, inactivate, desensitize or down regulate the biological activity and/or expression of a receptor or pathway of interest caused by the binding of a different compound to the receptor. The term “nucleic acid molecule” and “nucleotide sequence,” as used herein, refers to a single or double stranded covalently-linked sequence of nucleotides in which the 3' and 5' ends on each nucleotide are joined by phosphodiester bonds. The nucleic acid molecule can include deoxyribonucleotide bases or ribonucleotide bases, and can be manufactured synthetically in vitro or isolated from natural sources. The terms “polypeptide,” “peptide,” “amino acid sequence” and “protein,” used interchangeably herein, refer to a molecule formed from the linking of at least two amino acids. The link between one amino acid residue and the next is an amide bond and is sometimes referred to as a peptide bond. A polypeptide can be obtained by a suitable method known in the art, including isolation from natural sources, expression in a recombinant expression system, chemical synthesis or enzymatic synthesis. The terms can apply to amino acid polymers in which one or more amino acid residue is an artificial chemical mimetic of a corresponding naturally occurring amino acid, as well as to naturally occurring amino acid polymers and non-naturally occurring amino acid polymers. The term “amino acid,” as used herein, can be naturally occurring and synthetic amino acids, as well as amino acid analogs and amino acid mimetics that function in a manner similar to the naturally occurring amino acids. Naturally occurring amino acids are those encoded by the genetic code, as well as those amino acids that are later modified, e.g., hydroxyproline, gamma- carboxyglutamate and O-phosphoserine. Amino acid analogs and derivatives can refer to compounds that have the same basic chemical structure as a naturally occurring amino acid, i.e., a carbon that is bound to a hydrogen, a carboxyl group, an amino group and an R group, e.g., homoserine, norleucine, methionine sulfoxide and methionine methyl sulfonium. Such analogs can have modified R groups (e.g., norleucine) or modified peptide backbones, but retain the same basic chemical structure as a naturally occurring amino acid. Amino acid mimetics means chemical compounds that have a structure that is different from the general chemical structure of an amino acid, but that function in a manner similar to a naturally occurring amino acid. Non- limiting examples of amino acid include tryptophan, phenylalanine, histidine, glycine, cysteine, alanine, tyrosine, serine, methionine, asparagine, leucine, asparagine, threonine, isoleucine, proline, glutamic acid, aspartic acid, hydroxyl proline, arginine, cystine, glutamine, lysine, valine, ornithine, taurine, and combinations thereof. Active 118427983.2 11 069269.0689 PATENT The term “enantiomers” refers to a pair of stereoisomers that are non-superimposable mirror images of each other. A 1:1 mixture of a pair of enantiomers is a “racemic” mixture or a racemate. The term is used to designate a racemic mixture where appropriate. The term “enantiopure” refers to a sample that within the limits of detection consists of a single enantiomer. The term “diastereoisomers” refers to stereoisomers that have at least two asymmetric atoms, but which are not mirror-images of each other. The absolute stereochemistry is specified according to the Cahn-Ingold-Prelog R— S system. When a compound is a pure enantiomer, the stereochemistry at each chiral carbon can be specified by either R or S. Resolved compounds whose absolute configuration is unknown can be designated (+) or (-) depending on the direction (dextro or levorotatory) in which they rotate plane polarized light at the wavelength of the sodium D line. The term “isomers” refers to different compounds that have the same molecular formula but differ in arrangement and configuration of the atoms. Also, as used herein, the term “stereoisomer” refers to any of the various stereo isomeric configurations which can exist for a given compound of the presently disclosed subject matter and includes geometric isomers. It is understood that a substituent can be attached at a chiral center of a carbon atom. Also, as used herein, the terms “constitutional isomers” refers to different compounds which have the same numbers of, and types of, atoms but the atoms are connected differently. As used herein, the term “positively-charged” and “negatively-charged” refer to certain properties of compounds or functional groups. A charge is a property of some elementary particles that gives rise to an interaction between them and consequently to the host of material phenomena described as electrical. Charge occurs in nature in two forms, conventionally described as “positive” and “negative” in order to distinguish between the two kinds of interaction between particles. Two particles that have similar charges (both negative or both positive) interact by repelling each other; two particles that have dissimilar charges (one positive, one negative) interact by attracting each other. The natural unit of negative charge is the charge on an electron, which is equal but opposite in effect to the positive charge on the proton. Large-scale matter that consists of equal numbers of electrons and protons is electrically neutral. If there is an excess of electrons the body is negatively charged; an excess of protons results in a positive charge. A flow of charged particles, especially a flow of electrons, constitutes an electric current. Charge is measured in coulombs, the charge on an electron being 1.602 × 10⁻¹⁹ coulombs. As used herein, the term “alkyl” refers to a straight or branched C₁-C₂₀ hydrocarbon group consisting solely of carbon and hydrogen atoms, containing no unsaturation, and which is attached to the rest of the molecule by a single bond, e.g., methyl, ethyl, n-propyl, 1-methylethyl Active 118427983.2 12 069269.0689 PATENT (isopropyl), n-butyl, n-pentyl, 1,1-dimethylethyl (t-butyl). In certain embodiments, the term alkyl refers to a straight or branched C₁-C₆ hydrocarbon group. As used herein, the term “aryl” refers to aromatic radicals having in the range of about 6 to about 14 carbon atoms such as phenyl, naphthyl, tetrahydronapthyl, indanyl, biphenyl. As used herein, the term “arylalkyl” refers to an aryl group as defined above directly bonded to an alkyl group as defined above, e.g., —CH₂C₆H₅, and —C₂H₄C₆H₅. As used herein, the term “alkenyl” refers to a C2-C20 aliphatic hydrocarbon group containing at least one carbon-carbon double bond and which may be a straight or branched chain, e.g., ethenyl, 1-propenyl, 2-propenyl (allyl), iso-propenyl, 2-methyl-1-propenyl, 1-butenyl, 2- butenyl. In certain embodiments, the term alkenyl refers to a C2-C6 aliphatic hydrocarbon group. The term “alkynyl,” as used herein, refers to a C2-C20 aliphatic hydrocarbon group containing at least one carbon-carbon triple bond and which may be a straight or branched chain, e.g., ethynyl, 1-propynyl, 2-propynyl. In certain embodiments, the term alkynyl refers to a C₂- C6 aliphatic hydrocarbon group. As used herein, the term “cycloalkyl” denotes an unsaturated, non-aromatic mono- or multicyclic hydrocarbon ring system (containing, for example, C₃-C₆) such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl. Examples of multicyclic cycloalkyl groups (containing, for example, C6-C15) include perhydronapththyl, adamantyl and norbornyl groups bridged cyclic group or sprirobicyclic groups, e.g., spiro (4,4) non-2-yl. As used herein, the term “cycloalkalkyl” refers to a cycloalkyl as defined above directly attached to an alkyl group as defined above, that results in the creation of a stable structure such as cyclopropylmethyl, cyclobutylethyl, or cyclopentylethyl. As used herein, the term “heterocyclic” refers to a stable 3- to 15-membered ring radical, which consists of carbon atoms and one or more, for example, from one to five, heteroatoms selected from the group consisting of nitrogen, oxygen and sulfur. For purposes of this application, the heterocyclic ring radical may be a monocyclic or bicyclic ring system, which may include fused or bridged ring systems, and the nitrogen, carbon, oxygen or sulfur atoms in the heterocyclic ring radical may be optionally oxidized to various oxidation states. As used herein, the term “heteroaryl” refers to a heterocyclic ring wherein the ring is aromatic. As used herein, the term “heteroarylalkyl” refers to heteroaryl ring radical as defined above directly bonded to alkyl group. The heteroarylalkyl radical may be attached to the main structure at any carbon atom from alkyl group that results in the creation of a stable structure. Active 118427983.2 13 069269.0689 PATENT As used herein, the term “heterocyclyl” refers to a heterocylic ring radical as defined above. The heterocyclyl ring radical may be attached to the main structure at any heteroatom or carbon atom that results in the creation of a stable structure. 2. GPRC6A Receptors G protein-coupled receptor 6A (GPCR6A) is a membrane protein that recognizes molecules in the extracellular milieu. GPRC6A has been found expressed in taste cells and has shown taste receptor functions, such as chemical sensing of nutrients. In particular, GPRC6A detects food molecules that can elicit taste qualities and properties, e.g., improved palatability or kokumi taste. The detection of the molecules eliciting taste qualities by the GPCR6A receptor improves the willingness of the animal, e.g., cat or dog, to eat a particular food. Additional information concerning the properties of the GPCR6A receptor can be found in International Patent Application No. PCT/US2019/037097, which is incorporated by reference in its entirety. The presently disclosed subject matter provides compounds and flavor compositions that bind to GPRC6A receptors. The GPRC6A receptors of the present disclosure can include mammalian GPRC6A receptors such as, but not limited to, a feline GPRC6A receptor (fGPRC6A), a canine GPRC6A (cGPRC6A) and a human GPRC6A (hGPRC6A). In certain embodiments, a GPRC6A receptor for use in the presently disclosed methods encompasses a GPRC6A taste receptor having the nucleotide sequence set forth in SEQ ID NOs:1- 3, and/or the amino acid sequence set forth in SEQ ID NOs: 4-6, including fragments thereof (e.g., functional fragments thereof) and variants thereof. In certain embodiments, the GPRC6A receptor comprises an amino acid sequence as set forth in SEQ ID NOs: 4-6, or a sequence at least about 99, about 98, about 97, about 96, about 95, about 90, about 85 or about 80 percent homologous thereto (homology, as that term is used herein, can be measured using standard software such as BLAST or FASTA), and is encoded, for example, by a nucleic acid comprising a sequence as set forth in SEQ ID NOs: 1-3, or a sequence at least about 99, about 98, about 97, about 96, about 95, about 90, about 85 or about 80 percent homologous thereto (homology, as that term is used herein, can be measured using standard software such as BLAST or FASTA). In certain embodiment, the GPRC6A receptor comprises or consists of an amino acid sequence as set forth in SEQ ID NOs: 4-6. SEQ ID NOs: 1-6 are provided below. Cat GPRC6A nucleotide sequence (SEQ ID NO: 1) atggcactattgattacactgattacctgttttgtgattcctcttgctacttcccagacttgccagaccc ctgacgacttcgtggctgccacttctccagggcatgtcataattggaggtttattcgccattcatgaaaa aatgctgtcctcagaagactatcccagacgaccagaaatccagaagtgtgttgggtttgaaatatcaatt Active 118427983.2 14 069269.0689 PATENT tttcttcaaactcttgccatgattcacagcattgagatgatcaataattcaacactattatctggaatca aactggggtatgaaatctatgacacttgtacagaagtcacagtggcaatggcagccgctctgaggtttct ttctaagttcaacagctccagagaaatcatggagtttaaatgtgactattccagctacatgccaagggtt aaggctgtcataggtgctggctactcagaaataaccatggctgtctccaggatgttgaatttacagctta tgccacaggtgagttatgaatcaactgcagaaatcctaagtgacaaaattcgctttccttcatttttacg gactgtgcccagtgacttctatcaaactaaagcaatggcccacctgattgagaagtctggatggaactgg attggcatcatagccacagatgatgactatggacgaatggccctcaacacttttgcagttcagaccacag caaataatgtgtgcatagctttcaaagaagttctcccagccttcctctcagataataccatcgaagtcag gatcaatgagacacttgagaaaatcatagcagaagcccaggttaatgtcattgtggtattcctgaggcaa ttccatgttttcaatctcttcagtaaagctctagaaaggaatataaataagatatggattgctagtgata actggtcaacggccaccaagattacaaccattcctaatgttaaaaggattggcaaagttgtagggtttac ctttagaagagggaatatgtcttccttccattcctttcttcaaaatctgcatatatttcccagtgataat aacaaggtcttaaatgaatatgccacactcttgtctgcttgtgcatatgtcaaggacagtgatttgagtc agtgcatttccaaccattctcaggggactttggcctacaaggttaacaaggatatagaaaggaacttctc cctgagaaatgatttcctgtggaattatactgagccaggccttgttcacagtatccagcttgcagtactt gctcttggttatgccattcgggatctctgccaagctcgcgactgtcagaaccccaacgcctttcaaccat gggagttacttgatgcactaaaaaatgtgacattcactgatgaagggaattcatttcattttgatgctca tggggatatgaatactggatatgatgttgtgctctggaaggagattgatggtcacctgactatcaccaag atagcacaatatgatctgaagaatgatgtcttcgtcatcacagaccaagaaacaaaaaatgagttcagaa atcttaagcaaattcagtctaaatgctccaaggagtgcagtcctgggcaaatgaagaaaactacaagaag tcaacatatctgctgctatgaatgtgtgaactgtcctgaaaatcactacagtaaccagacagatatggat cactgccttttatgtaacaacgaaactcagtgggcccctgtaaagagcacagcatgctttgaaaaggaag tggagtatctcagttggaatgactccttggccatactgctcctggccctctccctactaggaatcatgtt tgttctggccattggcataatatttacaagaaacctgaacacgcctgttgtgaaatcgtccgggggattg ctggtctgctatgtgatccttctctgtcatttcctcaactttgccagcacgggctttttcattggagaac cacaagacttcacatgtaaaaccaggcagacgttttttggtgtgagcttcactctctgcatctcctgcat tttggtgaagtccctgaaaattctgctagccttcagcttcgaccccaagttgcagaacttcctgaagtgc ctctataaacccatccccatcatcttcatttgcacaggtatccaggttgccatttgcacagtctggctaa tctttgcagcacctgctgtggaagagaatgtctccttgcccagagtcattatcctggaatgtgaggaggg atccatccttgcatttggcatcatgctgggctatattgccatcctggccttcatttgcttcatatttgcc ttcaaaggcaggaaactacccgagaattacaatgaagccaaattcataacatttggcatgctcgtttatt tcatagcttggatcacattcgtccccgtctatgctaccacatttggtaaatatttaccagctgtggagat tatcattattttaatatcgaactatgggatcctgtgttgcacattcttccccaaatgctatgttattctt tataagcaggagactaacacaaaatctgcctttctcaagatgatttacagttactcttcccacagcgcaa gcagccttgccatgagtcacgtttccctggactcctctagcagcaacatcacagcgaccaatcccagctc cggtggcaggcctgcagcctggcaggaaagcagggatatccgggcacaagcatttgcacacacacgcaga gaaaacgctgcaagtatgtctaaaacttggcctcggaaaagaatttcaagtatttga Dog GPRC6A nucleotide sequence (SEQ ID NO: 2) atggcactattgattataccgattacctgctttgggagtactcttgttacttcccagccttgccagactc ctgatgactttgtggctgccacttctccaggacatatcatgattggaggtttatttgccattcatgagaa aatgctgccctcagaagactatcccagacgaccagaaatccagaagtgtgttggctttgaaatatcaatt tttcttcaaactcttgccatgattcatagcattgagatgatcaacaattcaacactattatccggagtca aactggggtatgaaatctatgacacctgtaccgaagtcacagtggcgatggcagccactctgaggtttct ctctaagcgcaactgctccagagaaattgtggagtttaagtgtgattattccagctacatgccaagagtt aaggctgtaataggtgctggctactcagaaataacaatggctgtctccaggatgctgaatttacagctca tgccacaggtgagttatgaatcaactgcagaaatcctaagtgacaaaattcgctttccttcatttttacg gactgtgcccagtgacttctatcaaactaaagcaatggcccacctgattcagaaatctggatggaactgg attggcatcatagccacagatgatgactacggacgactggccctcaacacttttgcagttcagaccgcag caaataatgtgtgcatagctttcaaggaggttctcccagccttcctctcagatgataccattgaaatcag gatcaatgagacccttgagaaaatcatcgcagaagcccaggttaatgtcattgtggtatttctgaggcaa ttccatgttttcaatctcttcactaaagctatagaaaagaatataaataagatctggattgccagtgata actggtccatggccaccaagatcaccaccatccctaatgttaaaaggattggcaaagttgtggggtttac ctttagaagagggaatatgtcttctttccactcctttcttcaaaacttgcatatgtttcccagagataat aacaagcccctaaatgaatatgccatgctcttgtctgcctgtgcacatgtcaaggacagtgatttgagtc agtgcatttccagccgctctcgggggactttggcctacacggctaacaaggatatagaaaggaacttctc Active 118427983.2 15 069269.0689 PATENT cctgagaaatgatttcctgtgggattacaccgagccgggacctgttcacagtatccagctcgcagttctt gcccttggttatgccattcgggatctctgccaagctcgagactgtcagaaccccaacgcctttcaaccat gggagttacttgatgtattaaaaaatgtgacattcactgatgaagggaattcatttcattttgatgccca tggggatatgaatactggatatgatgttgtgctctggaaggagattggcggccacatgactatcaccaag atggcacaatatgatctgaggaatgatgtcttcatcatcacagaccaagaaacaaaaaatgagttcagaa atcttaagcaaattcgatctaaatgctccaaggaatgcagtcctgggcaaatgaaaaaaactacaagaag tcaacatatctgctgctatgaatgtgtggactgtcctgaaaatcactacagtaaccagacagatatggat cactgcctcttatgcaacaatgaaactcactgggcccctgtcaggagcacaaggtgctttgaaaaggaag tggaatatctcaactggaatgattccttggctatactgctcctggccctctccctactaggaatcatcct tgttctggccattggcataatatttacaagaaacctgaacacacccattgtaaaatcatctgggggattg ctggtctgctacgtgatccttctctgtcatgtcctcaacttcgccagcacaggcttcttcattggagaac cacaagacttcacatgtaaaaccaggcagactgtatttggtgtgagcttcactctctgcatctcctgcat tttgatgaagtccctgaaaattctgctagccttcagcttcgatcccaagttgcagaacttcttgaagtgc ctctataaaccgatccccatcatcttcacttgcacaggtatccaggttgtcatttgcacaatctggctaa tctttgcagcacctgctgtggaagagaatgtctccttgcccagagtcattatcctggaatgtgaggaggg atccgtccttgcatttggcaccatgctgggttatattgccatcctggccttcatttgcttcatatttgca ttcaaaggcaggaaattacctgagcattacaacgaagccaaattcataacatttggcatgctcatttatt tcatagcttggatcacattcatccccatctatgctaccacatttggtaaatatttgccagctgtggagat tattgttattttaatttctaactatgggatcctgtgttgcacattcttccccaaatgctatattattctt tgtaagcaagaggctaacacaaaatctgcctttctcaagatgatttacagttactcttcccacactgcaa gcagccttgccattagtcatgtttcactggactccactaacagcagtatcacaacgaccaatcccagctc tagtggcaagtctgcagcctggcaggaaagcaaggatcttcaggcacaagcatttgcacacatatgcaga gaaaatgcgataagtgtacctaaaattttacctcgaaaaagaatttcaagtatatga Human GPRC6A nucleotide sequence (SEQ ID NO: 3) atggcattcttaattatactaattacctgctttgtgattattcttgctacttcacagccttgccagaccc ctgatgactttgtggctgccacttctccgggacatatcataattggaggtttgtttgctattcatgaaaa aatgttgtcctcagaagactctcccagacgaccacaaatccaggagtgtgttggctttgaaatatcagtt tttcttcaaactcttgccatgatacacagcattgagatgatcaacaattcaacactcttacctggagtca aactggggtatgaaatctatgacacttgtacagaagtcacagtggcaatggcagccactctgaggtttct ttctaaattcaactgctccagagaaactgtggagtttaagtgtgactattccagctacatgccaagagtt aaggctgtcataggttctgggtactcagaaataactatggctgtctccaggatgttgaatttacagctca tgccacaggtgggttatgaatcaactgcagaaatcctgagtgacaaaattcgctttccttcatttttacg gactgtgcccagtgacttccatcaaattaaagcaatggctcacctgattcagaaatctggttggaactgg attggcatcataaccacagatgatgactatggacgattggctcttaacacttttataattcaggctgaag caaataacgtgtgcatagccttcaaagaggttcttccagcctttctttcagataataccattgaagtcag aatcaatcggacactgaagaaaatcattttagaagcccaggttaatgtcattgtggtatttctgaggcaa ttccatgtttttgatctcttcaataaagccattgaaatgaatataaataagatgtggattgctagtgata attggtcaactgccaccaagattaccaccattcctaatgttaaaaagattggcaaagttgtagggtttgc ctttagaagagggaatatatcctctttccattcctttcttcaaaatctgcacttgcttcccagtgacagt cacaaactcttacatgaatatgccatgcatttatctgcctgcgcatatgtcaaggacactgatttgagtc aatgcatattcaatcattctcaaaggactttggcctacaaggctaacaaggctatagaaaggaacttcgt catgagaaatgacttcctctgggactatgctgagccaggactcattcatagtattcagcttgcagtgttt gcccttggttatgccattcgggatctgtgtcaagctcgtgactgtcagaaccccaacgcctttcaaccat gggagttacttggtgtgctaaaaaatgtgacattcactgatggatggaattcatttcattttgatgctca cggggatttaaatactggatatgatgttgtgctctggaaggagatcaatggacacatgactgtcactaag atggcagaatatgacctacagaatgatgtcttcatcatcccagatcaggaaacaaaaaatgagttcagga atcttaagcaaattcaatctaaatgctccaaggaatgcagtcctgggcaaatgaagaaaactacaagaag tcaacacatctgttgctatgaatgtcagaactgtcctgaaaatcattacactaatcagacagatatgcct cactgccttttatgcaacaacaaaactcactgggcccctgttaggagcactatgtgctttgaaaaggaag tggaatatctcaactggaatgactccttggccatcctactcctgattctctccctactgggaatcatatt tgttctggttgttggcataatatttacaagaaacctgaacacacctgttgtgaaatcatccgggggatta agagtctgctatgtgatccttctctgtcatttcctcaattttgccagcacgagctttttcattggagaac cacaagacttcacatgtaaaaccaggcagacaatgtttggagtgagctttactctttgcatctcctgcat tttgacgaagtctctgaaaattttgctagccttcagctttgatcccaaattacagaaatttctgaagtgc ctctatagaccgatccttattatcttcacttgcacgggcatccaggttgtcatttgcacactctggctaa tctttgcagcacctactgtagaggtgaatgtctccttgcccagagtcatcatcctggagtgtgaggaggg Active 118427983.2 16 069269.0689 PATENT atccatacttgcatttggcaccatgctgggctacattgccatcctggccttcatttgcttcatatttgct ttcaaaggcaaatatgagaattacaatgaagccaaattcattacatttggcatgctcatttacttcatag cttggatcacattcatccctatctatgctaccacatttggcaaatatgtaccagctgtggagattattgt catattaatatctaactatggaatcctgtattgcacattcatccccaaatgctatgttattatttgtaag caagagattaacacaaagtctgcctttctcaagatgatctacagttattcttcccatagtgtgagcagca ttgccctgagtcctgcttcactggactccatgagcggcaatgtcacaatgaccaatcccagctctagtgg caagtctgcaacctggcagaaaagcaaagatcttcaggcacaagcatttgcacacatatgcagggaaaat gccacaagtgtatctaaaactttgcctcgaaaaagaatgtcaagtatatga Cat GPRC6A amino acid sequence (SEQ ID NO:4) MALLITLITCFVIPLATSQTCQTPDDFVAATSPGHVIIGGLFAIHEKMLSSEDYPRRPEIQKCVGFEISI FLQTLAMIHSIEMINNSTLLSGIKLGYEIYDTCTEVTVAMAAALRFLSKFNSSREIMEFKCDYSSYMPRV KAVIGAGYSEITMAVSRMLNLQLMPQVSYESTAEILSDKIRFPSFLRTVPSDFYQTKAMAHLIEKSGWNW IGIIATDDDYGRMALNTFAVQTTANNVCIAFKEVLPAFLSDNTIEVRINETLEKIIAEAQVNVIVVFLRQ FHVFNLFSKALERNINKIWIASDNWSTATKITTIPNVKRIGKVVGFTFRRGNMSSFHSFLQNLHIFPSDN NKVLNEYATLLSACAYVKDSDLSQCISNHSQGTLAYKVNKDIERNFSLRNDFLWNYTEPGLVHSIQLAVL ALGYAIRDLCQARDCQNPNAFQPWELLDALKNVTFTDEGNSFHFDAHGDMNTGYDVVLWKEIDGHLTITK IAQYDLKNDVFVITDQETKNEFRNLKQIQSKCSKECSPGQMKKTTRSQHICCYECVNCPENHYSNQTDMD HCLLCNNETQWAPVKSTACFEKEVEYLSWNDSLAILLLALSLLGIMFVLAIGIIFTRNLNTPVVKSSGGL LVCYVILLCHFLNFASTGFFIGEPQDFTCKTRQTFFGVSFTLCISCILVKSLKILLAFSFDPKLQNFLKC LYKPIPIIFICTGIQVAICTVWLIFAAPAVEENVSLPRVIILECEEGSILAFGIMLGYIAILAFICFIFA FKGRKLPENYNEAKFITFGMLVYFIAWITFVPVYATTFGKYLPAVEIIIILISNYGILCCTFFPKCYVIL YKQETNTKSAFLKMIYSYSSHSASSLAMSHVSLDSSSSNITATNPSSGGRPAAWQESRDIRAQAFAHTRR ENAASMSKTWPRKRISSI Dog GPRC6A amino acid sequence (SEQ ID NO:5) MALLIIPITCFGSTLVTSQPCQTPDDFVAATSPGHIMIGGLFAIHEKMLPSEDYPRRPEIQKCVGFEISI FLQTLAMIHSIEMINNSTLLSGVKLGYEIYDTCTEVTVAMAATLRFLSKRNCSREIVEFKCDYSSYMPRV KAVIGAGYSEITMAVSRMLNLQLMPQVSYESTAEILSDKIRFPSFLRTVPSDFYQTKAMAHLIQKSGWNW IGIIATDDDYGRLALNTFAVQTAANNVCIAFKEVLPAFLSDDTIEIRINETLEKIIAEAQVNVIVVFLRQ FHVFNLFTKAIEKNINKIWIASDNWSMATKITTIPNVKRIGKVVGFTFRRGNMSSFHSFLQNLHMFPRDN NKPLNEYAMLLSACAHVKDSDLSQCISSRSRGTLAYTANKDIERNFSLRNDFLWDYTEPGPVHSIQLAVL ALGYAIRDLCQARDCQNPNAFQPWELLDVLKNVTFTDEGNSFHFDAHGDMNTGYDVVLWKEIGGHMTITK MAQYDLRNDVFIITDQETKNEFRNLKQIRSKCSKECSPGQMKKTTRSQHICCYECVDCPENHYSNQTDMD HCLLCNNETHWAPVRSTRCFEKEVEYLNWNDSLAILLLALSLLGIILVLAIGIIFTRNLNTPIVKSSGGL LVCYVILLCHVLNFASTGFFIGEPQDFTCKTRQTVFGVSFTLCISCILMKSLKILLAFSFDPKLQNFLKC LYKPIPIIFTCTGIQVVICTIWLIFAAPAVEENVSLPRVIILECEEGSVLAFGTMLGYIAILAFICFIFA FKGRKLPEHYNEAKFITFGMLIYFIAWITFIPIYATTFGKYLPAVEIIVILISNYGILCCTFFPKCYIIL CKQEANTKSAFLKMIYSYSSHTASSLAISHVSLDSTNSSITTTNPSSSGKSAAWQESKDLQAQAFAHICR ENAISVPKILPRKRISSI Human GPRC6A amino acid sequence (SEQ ID NO:6) MAFLIILITCFVIILATSQPCQTPDDFVAATSPGHIIIGGLFAIHEKMLSSEDSPRRPQIQECVGFEISV FLQTLAMIHSIEMINNSTLLPGVKLGYEIYDTCTEVTVAMAATLRFLSKFNCSRETVEFKCDYSSYMPRV KAVIGSGYSEITMAVSRMLNLQLMPQVGYESTAEILSDKIRFPSFLRTVPSDFHQIKAMAHLIQKSGWNW IGIITTDDDYGRLALNTFIIQAEANNVCIAFKEVLPAFLSDNTIEVRINRTLKKIILEAQVNVIVVFLRQ FHVFDLFNKAIEMNINKMWIASDNWSTATKITTIPNVKKIGKVVGFAFRRGNISSFHSFLQNLHLLPSDS HKLLHEYAMHLSACAYVKDTDLSQCIFNHSQRTLAYKANKAIERNFVMRNDFLWDYAEPGLIHSIQLAVF ALGYAIRDLCQARDCQNPNAFQPWELLGVLKNVTFTDGWNSFHFDAHGDLNTGYDVVLWKEINGHMTVTK MAEYDLQNDVFIIPDQETKNEFRNLKQIQSKCSKECSPGQMKKTTRSQHICCYECQNCPENHYTNQTDMP HCLLCNNKTHWAPVRSTMCFEKEVEYLNWNDSLAILLLILSLLGIIFVLVVGIIFTRNLNTPVVKSSGGL RVCYVILLCHFLNFASTSFFIGEPQDFTCKTRQTMFGVSFTLCISCILTKSLKILLAFSFDPKLQKFLKC LYRPILIIFTCTGIQVVICTLWLIFAAPTVEVNVSLPRVIILECEEGSILAFGTMLGYIAILAFICFIFA FKGKYENYNEAKFITFGMLIYFIAWITFIPIYATTFGKYVPAVEIIVILISNYGILYCTFIPKCYVIICK Active 118427983.2 17 069269.0689 PATENT QEINTKSAFLKMIYSYSSHSVSSIALSPASLDSMSGNVTMTNPSSSGKSATWQKSKDLQAQAFAHICREN ATSVSKTLPRKRMSSI In certain embodiments, the GPRC6A receptor for use in the presently disclosed methods can comprise a functional fragment of any GPRC6A receptor disclosed herein. In certain embodiments, GPRC6A is a Class C G-Protein-Coupled Receptor (GPCR) comprising three domains: a Venus Flytrap domain that binds to the receptor’s native ligands, a seven-helix transmembrane domain (7TM) that transmits signal to the cellular interior, and a cysteine rich domain (CRD) that connects the two. In certain embodiments, a functional fragment of GPRC6A is selected from the group consisting of the Venus Flytrap domain (amino acid residues 1-496), the Venus Flytrap domain including the CRD domain (amino acid residues 1-590), the 7TM domain (amino acid residues 591-842), the 7TM domain including a C-terminus helical extension (amino acid residues 594-857), any peptide substantially overlapping any one of the domains thereof, any variation thereof and any combination thereof. 3. GPRC6A Binding Site The presently disclosed subject matter provides for compounds that modulate the activity of a GPRC6A receptor, wherein the compounds interact with one or more amino acids in a domain of the GPRC6A receptor, for example, a Venus Flytrap domain. In certain embodiments, the GPRC6A receptor is a feline GPRC6A receptor. In certain embodiments, the disclosed compounds interact with amino acids that comprise 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or more of amino acid residues in the Venus Flytrap domain (VFT) of the feline GPRC6A, for example, Tyr148, Ser149, Glu170, Thr172, Asp 218, Tyr220, Arg279, Asp303, Asn304, Thr307, Arg399 and Asn400. In certain embodiments, the disclosed compounds interact with the amino acids that comprise 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or more of amino acid residues in the seven- transmembrane domain (7TM) of the feline GPRC6A, for example, Arg662, Gln663, Phe666, Gly667, Phe670, Gln715, Glu746, Ala751, Phe752, Met755, Leu756, Ile759, Tyr793, Trp797, Phe800, Tyr804, Glu816, Val819, Ile820. In certain embodiments, the GPRC6A receptor is a canine GPRC6A receptor. In certain embodiments, the disclosed compounds interact with amino acids that comprise 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or more of amino acid residues in the Venus Flytrap domain (VFT) of the canine GPRC6A, for example, Tyr148, Ser149, Glu170, Thr172, Asp 218, Tyr220, Arg279, Asp303, Asn304, Met307, Arg399 and Asn400. Active 118427983.2 18 069269.0689 PATENT In certain embodiments, the disclosed compounds interact with the amino acids that comprise 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or more of amino acid residues in the seven- transmembrane domain (7TM) of the canine GPRC6A, for example, Arg662, Gln663, Phe666, Gly667, Phe670, Gln715, Glu746, Ala751, Phe752, Met755, Leu756, Ile759, Tyr793, Trp797, Phe800, Tyr804, Glu816, Val819, Ile820. In certain embodiments, the interaction between a compound and one or more amino acids of the GPRC6A receptors described herein can comprise one or more hydrogen bond, covalent bond, non-covalent bond, salt bridge, physical interaction, and combinations thereof. The interactions can also be any interaction characteristic of a ligand receptor interaction known in the art. Such interactions can be determined by, for example, site directed mutagenesis, x-ray crystallography, x-ray or other spectroscopic methods, Nuclear Magnetic Resonance (NMR), cross-linking assessment, mass spectroscopy or electrophoresis, cryo-microscopy, displacement assays based on known agonists, structural determination and combinations thereof. In certain embodiments, the interactions are determined in silico, for example, by theoretical means such as docking a compound into a specific binding pocket using molecular docking, molecular modeling, molecular simulation, or other means known to persons of ordinary skill in the art. In a non-limiting example, the amino acids that interact with the composition undergo ring stacking interactions to the bound composition. In certain embodiments, the interaction between an amino acid in the 7TM interaction map or the VFT interaction map and the compound is a pi-pi interaction. In certain embodiments, the interaction between an amino acid in the 7TM interaction map or the VFT interaction map and the compound is a hydrogen bond interaction. In certain embodiments, the interaction between an amino acid in the 7TM interaction map or the VFT interaction map and the compound is a hydrophobic interaction. In certain embodiments, the interaction between an amino acid in the 7TM interaction map or the VFT interaction map and the compound is a van der Waals interaction. In certain embodiments, the amino acid in the 7TM interaction map or the VFT interaction map is a polar amino acid, wherein the amino acid interacts with the compound as a hydrogen bond donor and/or acceptor. In certain embodiments, the compounds interact with a GPRC6A receptor described herein according to any combination of interactions described herein, for example, one, two, three or more of the interactions. In certain embodiments, the compounds bind to at least one of the receptors described herein. In certain embodiments, the compounds bind selectively to only one of the receptors described herein. Active 118427983.2 19 069269.0689 PATENT 3.1. Compounds Binding to GPRC6A Receptors The present disclosure provides compounds that were found to bind to GPRC6A receptors and that enhance or modify the palatability, taste or flavor of a pet food product. As such, the compounds disclosed herein enhance or modify the kokumi taste profile of the pet food product containing the compounds. In certain embodiments, the compounds disclosed are compounds that bind specifically to the feline GPRC6A receptor. The compounds of the present disclosure were identified through various in vitro screening assays. For example, in certain embodiments, the compounds of the present application were identified through in vitro assays, wherein the compounds activate a GPRC6A receptor expressed by cells in vitro. In certain embodiments, the in vitro assay comprises measuring the biological activity of a GPRC6A receptor in the absence and/or presence of a compound. In certain embodiments, the in vitro assay can include measuring the biological activity of a GPRC6A receptor in the presence of varying concentrations of the compound. The in vitro assay can further include identifying the compounds that result in a modulation of the activity of the GPRC6A receptor compared to the activity and/or expression of the GPRC6A receptor in the absence of the test compound. In certain embodiments, in vitro assay comprises analyzing the effect of a test compound on the biological activity of a GPRC6A receptor in the presence of an allosteric modulator, for example, a positive allosteric modulator. In certain embodiments, the in vitro assay comprises the in vitro assays described in the Examples section of the present application. Additional information concerning the in vitro assay can be found in International Patent Application No. PCT/US2019/037097, which is incorporated by reference in its entirety. In certain embodiments, the compound that can modulate the activity of a GPRC6A receptor has an “EC50” value (the concentration that provokes a response halfway between the baseline and maximum response) of no more than about 200 μM. In certain embodiments, the compound has an EC50 value of no more than about 1 μM, about 2 μM, about 3 μM, about 4 μM, about 5 μM, about 6 μM, about 7 μM, about 8 μM, about 9 μM, about 10 μM, about 20 μM, about 30 μM, about 40 μM, about 50 μM, about 60 μM, about 70 μM, about 80 μM, about 90 μM, about 100 μM, about 110 μM, about 120 μM, about 130 μM, about 140 μM, about 150 μM, about 160 μM, about 170 μM, about 180 μM, about 190 μM or about 200 μM. In certain embodiments, the compound has an EC50 value of no more than about 250 μM, about 300 μM, about 400 μM, about 500 μM, about 600 μM, about 700 μM, about 800 μM, about 900 μM or about 1 mM. In certain embodiments, the compound has an EC50 value of at least 1 nM, 10 nM, or 100 nM, but no more than about 1 μM, about 2 μM, about 3 μM, about 4 μM, about 5 μM, about 6 μM, about 7 μM, Active 118427983.2 20 069269.0689 PATENT about 8 μM, about 9 μM, about 10 μM, about 20 μM, about 30 μM, about 40 μM, about 50 μM, about 60 μM, about 70 μM, about 80 μM, about 90 μM, about 100 μM, about 110 μM, about 120 μM, about 130 μM, about 140 μM, about 150 μM, about 160 μM, about 170 μM, about 180 μM, about 190 μM, about 200 μM, about 250 μM, about 300 μM, about 400 μM, about 500 μM, about 600 μM, about 700 μM, about 800 μM, about 900 μM or about 1 mM. In certain embodiments, the compound that can modulate the activity of a GPRC6A receptor has an EC50 value of no more than about 50 mM. In certain embodiments, the compound has an EC50 value of no more than about 1 mM, about 2 mM, about 3 mM, about 4 mM, about 5 mM, about 6 mM, about 7 mM, about 8 mM, about 9 mM, about 10 mM, about 20 mM, about 30 mM, about 40 mM or about 50 mM. In certain embodiments, the compound has an EC50 value of at least 1 nM, 10 nM, 100 nM, 1 μM, 10 μM, or 100 μM, but no more than about 1 mM, about 2 mM, about 3 mM, about 4 mM, about 5 mM, about 6 mM, about 7 mM, about 8 mM, about 9 mM, about 10 mM, about 20 mM, about 30 mM, about 40 mM or about 50 mM. In certain embodiments, the compound that can modulate the activity of a GPRC6A receptor has a maximum observed effect, an “Emax” value, of no less than about 0.1. As used herein, “Emax” refers to the efficacy or maximum response achievable. In certain embodiments, the compound has an Emax value of no less than about 0.1, about 0.2, about 0.3, about 0.4, about 0.5, about 0.6, about 0.7, about 0.8, about 0.9, about 1.0, about 1.1, about 1.2, about 1.3, about 1.4, about 1.5, about 1.6, about 1.7, about 1.8, about 1.9, about 2.0, about 2.5, about 3.0, about 3.5, about 4.0, about 4.5, about 5.0, about 5.5, about 6.0, about 6.5, about 7.0, about 7.5, about 8.0, about 8.5, about 9.0, about 9.5, about 10, about 15, about 20, about 25, about 30, about 40, about 50, about 60, about 70, about 80, about 90, about 100, about 110, about 120, about 130, about 140, about 150 or about 200. In certain embodiments, the compound has an Emax value of more than about 100. In certain embodiments, the modulation of the activity of a GPRC6A receptor is measured using a relative activation of a compound compared to a maximal stimulator, e.g., a percent activation compared to a maximal stimulator. In certain embodiments, the compound has a percent activation compared to a maximal stimulator of no less than about 1.5, about 1.6, about 1.7, about 1.8, about 1.9, about 2.0, about 2.5, about 3.0, about 3.5, about 4.0, about 4.5, about 5.0, about 5.5, about 6.0, about 6.5, about 7.0, about 7.5, about 8.0, about 8.5, about 9.0, about 9.5, about 10, about 15, about 20, about 25, about 30, about 40, about 50, about 60, about 70, about 80, about 90, about 100, about 110, about 120, about 130, about 140, about 150 or about 200. In certain embodiments, the compound has a percent activation compared to a maximal stimulator of more than about 200. In certain embodiments, the maximal stimulator comprises any GPRC6A agonists, e.g., Calindol, testosterone, L-amino acids, e.g., L-arginine, L-Lysine, L- Active 118427983.2 21 069269.0689 PATENT ornithine, and any combination thereof. In certain embodiments, the maximal stimulator further comprises an allosteric modulator, e.g., a positive allosteric modulator. In certain embodiments, the allosteric modulator is an alkaline earth cation (e.g., Be²⁺, Mg²⁺, Ca²⁺, Sr²⁺, and Ba²⁺). In certain embodiments, the allosteric modulator is Mg²⁺. In certain embodiments, the maximal stimulator can be a nucleoside triphosphate. In certain embodiments, the nucleoside triphosphate is an adenosine triphosphate (ATP), a guanosine triphosphate (GTP), a cytidine triphosphate (CTP) and/or a thymidine triphosphate (TTP). In alternative embodiments, the compounds of the present application were identified through in silico modeling of the GPRC6A receptor, wherein the compound of the present application comprises a structure that fits within a binding site of the GPRC6A receptor. In certain embodiments, the in silico modeling comprises predicting the three-dimensional structure (3D) of a GPRC6A receptor and screening the predicted 3D structure with putative GPRC6A receptor modulating compounds. The in silico modeling can further include predicting whether the putative compound would interact with the binding site of the receptor by analyzing the potential interactions with the putative compound and the amino acids of the receptor. The in silico modeling can further include identifying a test compound that can bind to and/or modulate the biological activity of the GPRC6A receptor by determining whether the 3D structure of the compound fits within the binding site of the 3D structure of the receptor. In certain embodiments, 3D models of a GPRC6A receptor can be built using crystal structures of other GPCRs as templates for homology modeling. For example, and not by way of limitation, structural models of the Venus Flytrap domain can be generated using the crystal structures of Class C GPCRs. In certain embodiments, a structural model of a GPRC6A receptor can be based on a known or a combination of known crystal structures of GPCRs. (See, e.g., Lee et al., Eur J Pharmacol. 2015 May 14. pii: S0014-2999(15)30012-1, which is incorporated by reference in its entirety herein). In certain embodiments, the in silico modeling is described in the Examples section of the present application. Additional information concerning the in silico modeling can be found in International Patent Application No. PCT/US2019/037097, which is incorporated by reference in its entirety. 3.2. General Motifs As a result of the extensive screening methods, the presently disclosed subject matter provides for an array of different compounds. In a particular non-limiting embodiment, certain compounds of the presently disclosed subject matter can fall within particular motifs. In certain embodiments, the GPRC6A modulating compound has the general formula (1): Active 118427983.2 22 069269.0689 PATENT In certain embodiments, R1 is H, C1-C20 alkyl (branched or unbranched), C1-C20 alkenyl (branched or unbranched), C1-C20 alkynyl (branched or unbranched), arylalkyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, heteroarylalkyl, haloalkyl, CF₃, halogen (e.g., F, Cl, Br, I), phenyl, - C(O)R₃, -COOR₃, -NR₃R₄, -NO₂, -OH, -OR₃, -CONR₃R₄, -S-Aryl, -O-Aryl, -N-Aryl, -NO₂, -S- O3H, -SO2R3, -NHOH, -C=CR3, -C=NOH, -OP(O)(OH)2, or CHO, where R1 is optionally substituted. Substitutions include, but are not limited to, H, C1-C20 alkyl (branched or unbranched), C₁-C₂₀ alkenyl (branched or unbranched), C₁-C₂₀ alkynyl (branched or unbranched), arylalkyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, heteroarylalkyl, haloalkyl, or halogen. In certain embodiments, R2 is H, C1-C20 alkyl (branched or unbranched), C1-C20 alkenyl (branched or unbranched), C₁-C₂₀ alkynyl (branched or unbranched), arylalkyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, or heteroarylalkyl. In particular embodiments, R2 is H or methyl. In certain embodiments, R3 and R4 are each independently selected from H, C1-C20 alkyl (branched or unbranched), C₁-C₂₀ alkenyl (branched or unbranched), C₁-C₂₀ alkynyl (branched or unbranched), arylalkyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, or heteroarylalkyl, haloalkyl, CF3, halogen (F, Cl, Br, I). In certain embodiments, the GPRC6A modulating compound has the general formula In certain embodiments, R is H, C₁-C₂₀ alkyl (branched or unbranched), C₁-C₂₀ alkenyl (branched or unbranched), C₁-C₂₀ alkynyl (branched or unbranched), arylalkyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, heteroarylalkyl, haloalkyl, CF3, halogen (F, Cl, Br, I), phenyl, -C(O)R1, -COOR1, -NR1R2, -NO2, -OH, -OR1, -CONR1R2, -S-Aryl, -O-Aryl, -N-Aryl, -NO2, -SO3H, - SO₂R₁, -NHOH, -C=CR₁, -C=NOH, -OP(O)(OH)₂, or CHO, where R is optionally substituted. Substitutions include, but are not limited to, H, C1-C20 alkyl (branched or unbranched), C1-C20 alkenyl (branched or unbranched), C1-C20 alkynyl (branched or unbranched), arylalkyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, heteroarylalkyl, haloalkyl, or halogen. Active 118427983.2 23 069269.0689 PATENT In certain embodiments, R1 and R2 are each independently selected from H, C1-C20 alkyl (branched or unbranched), C₁-C₂₀ alkenyl (branched or unbranched), C₁-C₂₀ alkynyl (branched or unbranched), arylalkyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, or heteroarylalkyl, haloalkyl, CF3, halogen (F, Cl, Br, I).In an alternative embodiment, the GPRC6A modulating compound falls within a motif according to a combination of the following four (4) criteria. The compound: i. includes an L-amino-acid; ii. includes one carbon after the ^^-carbon of the amino-acid unit; iii. can include a positively-charged group at a distance up to ~9A from the ^^-carbon (alpha carbon denoting the carbon of the compound to the amino group to the carboxyl group); and iv. does not include a negatively-charged group at a distance up to ~9A from ^^-carbon. Under this motif, the compound of the presently disclosed subject matter should meet all 4 criteria. These criteria were determined on the basis of the structural analysis of the VFT domains and the results of the Quantitative Structure-Activity Relationship (QSAR) of binding ligands which were experimentally verified. In alternative embodiments, the presently disclosed subject matter discloses compounds that bind to the GPRC6A receptor that fall outside of a general motif, but still enhance or modify the kokumi and/or umami taste profile in pet food products. 3.3. Compounds The presently disclosed subject matter provides various compounds that bind to the GPRC6A receptor. These compounds include, but are not limited to, hormones, peptides, amino acids, ions, metals, butanoic acid-based compounds, propanoic acid-based compounds, pentanoic acid-based compounds, and carboxylic acid-based compounds, among others compounds. Non- limiting compounds of the presently disclosed subject matter are provided below in Table 1. Table 1. G^{eneral Category} _{Chemical Name} Amino acids, L-Alanine peptides, salts L-Arginine thereof, and D-Arginine derivatives thereof L-Asparagine L-Canavanine L-Glutamine Glycine L-Histidine Active 118427983.2 24 069269.0689 PATENT ^{General Category} _{Chemical Name} L-Carnosine L-Citrulline L-Cysteine L-Ethionine L-Leucine L-Tyrosine L-Valine L-Lysine L-Methionine L-Serine L-Threonine L-Tryptophan L-Valine L-Phenylalanine L-Isoleucine L-Ornithine L-Homoargininie L-Homocysteine L-Methionine sulfoxide L-NAME hydrochloride Homoserine, (S)-2-Amino-4-hydroxybutyric acid 3-(2-Thienyl)-L-alanine DL-5-Hydroxylysine hydrochloride N^G,NG-Dimethylarginine dihydrochloride NG-amino-L-Arginine (hydrochloride) NG-Hydroxy-L-arginine, monoacetate salt N^G-Methyl-L-arginine acetate salt L-4-Thialysine hydrochloride H-ASP(OBZL)-OH nor-NOHA (acetate) Nω-Nitro-L-arginine Se-(Methyl)selenocysteine Ions, metals, salts Calcium chloride thereof, and Gadolinium ion derivatives thereof Strontium hydroxide Terbium (III) acetate hydrate Praesodymium (III) trifluromethane sulfonate Butanoic acid-based (2S,3R)-2-amino-3-methoxybutanoic acid, O-methyl threonine compounds, salts 2-amino-4-oxo-4-(thiophen-2-yl)butanoic acid hydrochloride thereof, and 2-amino-4-oxo-4-phenylbutanoic acid hydrochloride derivatives thereof (2S)-2-amino-4-(ethylcarbamoyl)butanoic acid methyl 2-amino-4-(piperidin-1-yl)butanoate dihydrochloride methyl 2-amino-4-carbamoylbutanoate Propanoic acid-based 2-amino-3-methoxypropanoic acid hydrochloride, O-methyl serine compounds, salts 2-amino-3-(methylthio)propanoic acid, S-methyl cysteine thereof, and 2-amino-3-(piperidin-1-yl)propanoic acid dihydrochloride derivatives thereof 2-amino-3-[(4-aminophenyl)sulfanyl]propanoic acid 2-amino-3-[benzyl(methyl)amino]propanoic acid 2-amino-3-[methyl(phenyl)amino]propanoic acid 2-amino-3-carbamimidamido propanoic acid Active 118427983.2 25 069269.0689 PATENT G^{eneral Category} _{Chemical Name} 2-amino-3-cyclobutylpropanoic acid hydrochloride[HCl] L-BMAA hydrochloride S(+)-2-Amino-3-(methylamino)propionic acid hydrochloride Dl-2,3-diaminopropionic acid HCl 2-amino-3-[(2-methoxy-2-oxoethyl)sulfanyl]propanoic acid (2R)-2-amino-3-methanesulfonylpropanoic acid Pentanoic acid-based (2S)-2-amino-5-{[(benzyloxy)carbonyl]amino}pentanoic acid compounds, salts L-Norvaline, (S)-(+)-2-Aminopentanoic acid, (S)-2-Aminovaleric acid thereof, and (2S)-2-amino-5-(tert-butoxy)-5-oxopentanoic acid derivatives thereof (2S)-2-amino-5-(benzyloxy)-5-oxopentanoic acid Others aminoisobutyric acid 2-amino-2-cyclopentylacetic acid The presently disclosed subject matter includes stereoisomers, enantiomers, diastereomers, or racemates of the compounds. The compounds of the presently disclosed subject matter can contain one or more asymmetric centers and can thus give rise to enantiomers, diastereomers, and other stereoisomeric forms that can be defined, in terms of absolute stereochemistry, as (R)- or (S)-. The presently disclosed subject matter is meant to include all such possible isomers, including racemic mixtures, optically pure forms, and intermediate mixtures. Optically active (R)- and (S)-isomers can be prepared using chiral synthons or chiral reagents or resolved using conventional techniques. If the compound contains a double bond, the substituent can be E or Z configuration. If the compound contains a disubstituted cycloalkyl, the cycloalkyl substituent can have a cis- or trans-configuration. All tautomeric forms are also intended to be included. In certain embodiments, the compounds of the present disclosure can include a salt form of the compound. Such salt forms include, but are not limited to, an acetate salt, a formate salt, a TFA salt or a sulfonate salt. In certain embodiments, the compound salt comprises an anion (-) (for example, but not limited to, Cl-, O^2-, CO3^2-, HCO3-, OH-, NO3-, PO4^3-, SO4^2-, CH3COO-, HCOO- and C2O4^2-) bonded via an ionic bond with a cation (+) (for example, but not limited to, Al³⁺, Ca²⁺, Na⁺, K⁺, Cu²⁺, H⁺, Fe³⁺, Mg²⁺, NH₄ ⁺ and H₃O⁺). In other embodiments, the compound salt comprises a cation (+) bonded via an ionic bond with an anion (-). In certain embodiments, the compounds of the present disclosure can be generated using standard chemosynthesis processes. In certain embodiments, the chemosynthesis process provides a compound having a purity of at least 99.999%, or at least 99%, or at least 95%, or at least 90%, or at least 85 or at least 80%. In certain embodiments, the compounds can be prepared using standard hydrolysis processes such as those employing acids, enzymes or a combination of acids and enzymes. Active 118427983.2 26 069269.0689 PATENT The compounds of the present disclosure can also be generated under food preparation conditions, e.g., during the production of a pet food product. For example, but not by way of limitation, the compounds of the present disclosure can be generated during a thermal food process, e.g., sterilization, retorting and/or extrusion, from precursor compounds present in the pet food. In certain embodiments, a liquid and/or a powder palatant can also be added to enhance the taste of a pet food, e.g., to a dry pet food product, and to increase the palatability of the pet food. The palatant can be a digest of meat (e.g., liver) and/or a digest of a vegetable, and can optionally include other palatants known in the art. In certain embodiments, the compound can be admixed with or generated in the liquid and/or powder palatant prior to its addition to the pet food product. Alternatively or additionally, the compound can be admixed with or generated in the liquid and/or powder palatant after its addition to the pet food product. 4. Flavor Compositions The presently disclosed subject matter also provides for flavor compositions that can be used to increase the palatability of a pet food product. The flavor compositions can comprise one or more the compounds disclosed herein (among other optional ingredients) and can be added to the pet food product in various delivery systems. In certain embodiments, the compounds of the present application are blended together in various ratios or are blended together with other compounds, e.g., nucleotides and/or amino acids and/or furanones, to form various flavor compositions. Non-limiting examples of nucleotides, amino acids and furanones are disclosed in Patent Application Nos. PCT/EP2013/072788, PCT/EP2013/072789, PCT/EP2013/072790, and PCT/EP2013/072794, which are incorporated herein by reference in their entireties. In certain embodiments, at least one, at least two, at least three, or at least four or more compounds of the presently disclosed subject matter are included in a flavor composition. In a specific embodiment, at least one compound of the presently disclosed subject matter are included in a flavor composition. In another embodiment, at least two compounds of the presently disclosed subject matter are included in a flavor composition. In certain embodiments, the at least one compound is present in the flavor composition in an amount of from about 0.0001 to about 10% weight/weight (w/w). For example, but not by way of limitation, the at least one compound can be present in the amount from about 0.0001% to about 10%, from about 0.0001% to about 1%, from about 0.0001% to about 0.1% , from about 0.0001 to about 0.01%, from about 0.0001% to about 0.001%, from about 0.001% to about 10%, from about 0.001% to about 1%, from about 0.01% to about 1% or from about 0.1% to about 1%, and values in between. In certain embodiments, the at least one compound is present in the flavor Active 118427983.2 27 069269.0689 PATENT composition in an amount of from about 0.0001% to about 5%, or from about 0.001% to about 5%, from about 0.01% to about 5% w/w, or from about 0.1% to about 5% w/w, and values in between. In certain embodiments of the present application, the at least one compound is present in the flavor composition in an amount of from about 0.0001% to about 1%, or from about 0.001% to about 1%, from about 0.01% to about 1% w/w, or from about 0.1% to about 1% w/w, and values in between. In certain embodiments, the at least one compound is present in the flavor composition in an amount of from about 0.001% to about 10% w/w. In certain embodiments, the compounds of the present disclosure can be blended together in various ratios or are blended together with other compounds, e.g., nucleotides, and/or furanones, and/or amino acids, and/or umami receptor activating transmembrane compounds, and/or nucleotide derivatives to form various flavor compositions. Non-limiting examples of nucleotides, nucleotide derivatives, furanones, amino acids, fatty acid receptor (GPR120) activating compounds, and umami receptor activating transmembrane compounds are disclosed in International Application Nos. PCT/EP2013/072788 filed Oct.31, 2013, PCT/EP2013/072789 filed Oct.31, 2013, PCT/EP2013/072790 filed Oct.31, 2013, PCT/EP2013/072794 filed Oct.31, 2013, PCT/US15/65046 filed Dec. 10, 2015, PCT/US15/65036 filed Dec. 10, 2015, and PCT/US15/65106 filed Dec. 10, 2015, which are incorporated herein by reference in their entireties. In addition to the compounds of the present disclosure, the flavor composition can include additional components. Such additional ingredients can include one or more of additional flavors, carriers, salts, bases, or the like. In certain embodiments, the flavor compositions of the present disclosure can be added to a pet food product, in an amount effective to modify, enhance or otherwise alter a taste or taste profile of the pet food product. The resulting modification can include, for example, an increase or enhancement in the kokumi taste of the pet food product, as determined by animals, e.g., cats and/or dogs, or in the case of formulation testing, as determined by a panel of animal taste testers, e.g., cats and/or dogs, via procedures known in the art. In certain embodiments, the flavor composition is added to a pet food product in an amount that is sufficient to modulate, activate and/or enhance a GPRC6A receptor. The concentration of flavor composition admixed with a pet food product to modulate and/or improve the palatability and/or kokumi taste of the pet food product can vary depending on variables, such as, for example, the specific type of pet food product, what compounds are already present in the pet food product and the concentrations thereof. 5. Pet Food Products Active 118427983.2 28 069269.0689 PATENT The compounds and/or flavor compositions of the presently disclosed subject matter can be used in a wide variety of pet food products. In certain embodiments, the compound is directly added to a pet food product. In certain embodiments, a flavor composition is directly added a pet food product. The combination of the compounds and/or flavoring composition(s) of the presently disclosed subject matter together with a pet food product and optional ingredients, when desired, provides an unexpected taste and imparts, for example, a kokumi sensory experience. The compounds and/or flavor compositions disclosed herein can be added prior to, during or after formulation processing or packaging of the pet food product, and the components of the flavor composition can be added sequentially or simultaneously. In certain embodiments, one or more of the components of the flavor compositions disclosed herein can be generated during the production of the pet food product from precursor compounds, e.g., during thermal food processing. For example, and not by way of limitation, a compound of a flavor composition can be generated during the production of a pet food product and additional components of the flavor composition can be added prior to, during or after formulation processing or packaging of the pet food product. In certain embodiments, one or more compound of the presently disclosed subject matter can be added directly to a food product. In certain embodiments, the compound of the present disclosure is present in a food product in an amount that is sufficient to modulate, activate and/or enhance a GPRC6A receptor. For example, but not by way of limitation, a compound can be present in a food product in an amount from about 1 nM to about 1 M, from about 1 μM to about 1 M, from about 1 mM to about 1 M, from about 10 mM to about 1 M, from about 100 mM to about 1 M, from about 250 mM to about 1 M, from about 500 mM to about 1 M, from about 750 mM to about 1 M, from about 0.001 μM to about 1 M, from about 0.001 μM to about 750 mM, from about 0.001 μM to about 500 mM, from about 0.001 μM to about 250 mM, from about 0.001 μM to about 100 mM, from about 0.001 μM to about 50 mM, from about 0.001 μM to about 25 mM, from about 0.001 μM to about 10 mM, from about 0.001 μM to about 1 mM, from about 0.001 μM to about 100 μM or from about 0.001 μM to about 10 μM, and values in between. In certain embodiments, where the compound of interest is an amino acid, the amino acid can be present in a food product in an amount of from about 1 mM to about 1 M, or from about 250 mM to about 1 M, or from about 5 mM to about 500 mM, or from about 10 mM to about 100 mM, or from about 15 mM to about 50 mM, or from about 20 mM to about 40 mM of the pet food product. In certain embodiments, the amino acid(s) can be present at an amount less than about 1 M, less than about 200 mM, less than about 100 mM, less than about 50 mM, less than about 20 mM or less than about 10 mM of the pet food product. In certain embodiments, the amino acid, Active 118427983.2 29 069269.0689 PATENT alone or in combination with other compounds, can be present in an amount of about 25 mM of the pet food product. In an alternative embodiment, the compound is present in a pet food product in an amount of from about 0.001 ppm to about 10,000 ppm. For example, but not by way of limitation, the compound can be present in the amount from about 0.001 ppm to about 7,500 ppm, from about 0.001 ppm to about 5,000 ppm, from about 0.001 ppm to about 2,500 ppm, from about 0.001 ppm to about 1,000 ppm, from about 0.001 ppm to about 750 ppm, from about 0.001 ppm to about 500 ppm, from about 0.001 ppm to about 250 ppm, from about 0.001 ppm to about 150 ppm, from about 0.001 ppm to about 100 ppm, from about 0.001 ppm to about 75 ppm, from about 0.001 ppm to about 50 ppm, from about 0.001 ppm to about 25 ppm, from about 0.001 ppm to about 15 ppm, from about 0.001 ppm to about 10 ppm, from about 0.001 ppm to about 5 ppm, from about 0.001 ppm to about 4 ppm, from about 0.001 ppm to about 3 ppm, from about 0.001 ppm to about 2 ppm, from about 0.001 ppm to about 1 ppm, from about 0.01 ppm to about 10,000 ppm, from about 0.01 ppm to about 7,500 ppm, from about 0.01 ppm to about 5,000 ppm, from about 0.01 ppm to about 2,500 ppm, from about 0.1 ppm to 1,000 ppm, from about 1 ppm to 1,000 ppm, from about 2 ppm to about 1,000 ppm, from about 3 ppm to about 1,000 ppm, from about 4 ppm to about 1,000 ppm, from about 5 ppm to about 1,000 ppm, from about 10 ppm to about 1,000 ppm, from about 15 ppm to about 1,000 ppm, from about 25 ppm to about 1,000 ppm, from about 50 ppm to about 1,000 ppm, from about 75 ppm to about 1,000 ppm, from about 100 ppm to about 1,000 ppm, from about 150 ppm to about 1,000 ppm, from about 250 ppm to about 1,000 ppm, from about 250 ppm to about 1,000 ppm, from about 500 ppm to about 1,000 ppm or from about 750 ppm to about 1,000 ppm, and values in between. In certain embodiments, the compound is present in the pet food product at an amount greater than about 0.001 ppm, greater than about 0.01 ppm, greater than about 0.1 ppm, greater than about 1 ppm, greater than about 2 ppm, greater than about 3 ppm, greater than about 4 ppm, greater than about 5 ppm, greater than about 10 ppm, greater than about 25 ppm, greater than about 50 ppm, greater than about 75 ppm, greater than about 100 ppm, greater than about 250 ppm, greater than about 500 ppm, greater than about 750 ppm, greater than about 1,000 ppm, greater than about 2,500 ppm, greater than about 5,000 ppm, greater than about 7,500 ppm, or greater than about 10,000 ppm, and values in between. In certain embodiments of the present application, the compound is admixed with a food product wherein the compound is present in an amount of from about 0.0001 to about 10% weight/weight (w/w) of the food product. For example, but not by way of limitation, the compound can be present in the amount from about 0.0001% to about 10%, from about 0.0001% to about 1%, from about 0.0001% to about 0.1% , from about 0.0001 to about 0.01%, from about Active 118427983.2 30 069269.0689 PATENT 0.0001% to about 0.001%, from about 0.001% to about 10%, from about 0.001% to about 1%, from about 0.01% to about 1% or from about 0.1% to about 1%, and values in between. In another embodiment, flavor compositions containing one or more of the disclosed compounds can be added to food products. A broad range of concentrations of the flavor compositions can be employed to provide such kokumi and/or umami taste and/or palatability modification. In certain embodiments of the present application, the flavor composition is admixed with a pet food product wherein the flavor composition is present in an amount of from about 0.001 ppm to about 10,000 ppm. For example, but not by way of limitation, the flavor composition can be present in the amount from about 0.001 ppm to about 10,000 ppm, from about 0.001 to about 7,500 ppm, from about 0.001 ppm to about 5,000 ppm, from about 0.001 ppm to about 2,500 ppm, from about 0.001 ppm to about 1,000 ppm to about 750 ppm, from about 0.001 ppm to about 500 ppm, from about 0.001 ppm to about 250 ppm, from about 0.001 ppm to about 150 ppm, from about 0.001 ppm to about 100 ppm, from about 0.001 ppm to about 75 ppm, from about 0.001 ppm to about 50 ppm, from about 0.001 ppm to about 25 ppm, from about 0.001 ppm to about 15 ppm, from about 0.001 ppm to about 10 ppm, from about 0.001 ppm to about 5 ppm, from about 0.001 ppm to about 4 ppm, from about 0.001 ppm to about 3 ppm, from about 0.001 ppm to about 2 ppm, from about 0.001 ppm to about 1 ppm, from about 0.01 ppm to about 10,000 ppm, from about 0.01 ppm to about 7,500 ppm, from about 0.01 ppm to about 5,000 ppm, from about 0.01 ppm to about 2,500 ppm, from about 0.1 ppm to 1,000 ppm, from about 1 ppm to 1,000 ppm, from about 2 ppm to about 1,000 ppm, from about 3 ppm to about 1,000 ppm, from about 4 ppm to about 1,000 ppm, from about 5 ppm to about 1,000 ppm, from about 10 ppm to about 1,000 ppm, from about 15 ppm to about 1,000 ppm, from about 25 ppm to about 1,000 ppm, from about 50 ppm to about 1,000 ppm, from about 75 ppm to about 1,000 ppm, from about 100 ppm to about 1,000 ppm, from about 150 ppm to about 1,000 ppm, from about 250 ppm to about 1,000 ppm, from about 250 ppm to about 1,000 ppm, from about 500 ppm to about 1,000 ppm or from about 750 ppm to about 1,000 ppm, and values in between. In certain embodiments, the flavor composition is present in the pet food product at an amount greater than about 0.001 ppm, greater than about 0.01 ppm, greater than about 0.1 ppm, greater than about 1 ppm, greater than about 2 ppm, greater than about 3 ppm, greater than about 4 ppm, greater than about 5 ppm, greater than about 10 ppm, greater than about 25 ppm, greater than about 50 ppm, greater than about 75 ppm, greater than about 100 ppm, greater than about 250 ppm, greater than about 500 ppm, greater than about 750 ppm, greater than about 1,000 ppm, greater than about 2,500 ppm, greater than about 5,000 ppm, greater than about 7,500 ppm, greater than about 10,000 ppm, and values in between. Active 118427983.2 31 069269.0689 PATENT In certain embodiments of the present application, the flavor composition is admixed with a food product wherein the flavor composition is present in an amount of from about 0.0001 to about 10% weight/weight (w/w) of the food product. For example, but not by way of limitation, the flavor composition can be present in the amount from about 0.0001% to about 10%, from about 0.0001% to about 1%, from about 0.0001% to about 0.1% , from about 0.0001 to about 0.01%, from about 0.0001% to about 0.001%, from about 0.001% to about 10%, from about 0.001% to about 1%, from about 0.01% to about 1% or from about 0.1% to about 1%, and values in between. In certain embodiments, the flavor composition is admixed with a food product in an amount from about 1 nM to about 1 M, from about 1 μM to about 1 M, from about 1 mM to about 1 M, from about 10 mM to about 1 M, from about 100 mM to about 1 M, from about 250 mM to about 1 M, from about 500 mM to about 1 M, from about 750 mM to about 1 M, from about 1 μM to about 1 M, from about 1 μM to about 750 mM, from about 1 μM to about 500 mM, from about 1 μM to about 250 mM, from about 1 μM to about 100 mM, from about 1 μM to about 50 mM, from about 1 μM to about 25 mM, from about 1 μM to about 10 mM, from about 1 μM to about 1 mM, from about 1 μM to about 100 μM or from about 1 μM to about 10 μM, and values in between. Non-limiting examples of suitable pet food products include wet food products, dry food products, moist food products, pet food supplements (e.g., vitamins), pet beverage products, snack and treats and pet food categories described herein. In certain embodiments, the pet food product is a nutritionally complete dry food product. A dry or low moisture-containing nutritionally-complete pet food product can comprise less than about 15% moisture, and include from about 10% to about 60% fat, from about 10% to about 70% protein and from about 30% to about 80% carbohydrates, e.g., dietary fiber and ash. In certain embodiments, the pet food product is a nutritionally complete wet food product. A wet or high moisture-containing nutritionally-complete pet food product can comprise greater than about 50% moisture. In certain embodiments, the wet pet food product includes from about 40% fat, from about 50% protein and from about 10% carbohydrates, e.g., dietary fiber and ash. In certain embodiments, the pet food product is a nutritionally complete moist food product. A moist, e.g., semi-moist or semi-dry or soft dry or soft moist or intermediate or medium moisture containing nutritionally-complete pet food product comprises from about 15% to about 50% moisture. In certain embodiments, the pet food product is a pet food snack product. Non-limiting examples of pet food snack products include snack bars, pet chews, crunchy treats, cereal bars, snacks, biscuits and sweet products. Active 118427983.2 32 069269.0689 PATENT In certain embodiments, the protein source can be derived from a plant source, such as lupin protein, wheat protein, soy protein and combinations thereof. Alternatively or additionally, the protein source can be derived from a variety of animal sources. Non-limiting examples of animal protein include beef, pork, poultry, lamb, or fish including, for example, muscle meat, meat byproduct, meat meal or fish meal. In certain embodiments, the present disclosure relates to methods for modulating the taste of a pet food product comprising: a) providing at least one pet food product, or a precursor thereof, and b) combining the pet food product, or precursor thereof, with at least a taste modulating amount of at least one flavor composition, for example, comprising one or more compound, or a comestibly acceptable salt thereof, so as to form an enhanced pet food product. In certain embodiments, the flavor composition comprises an allosteric modulator, for example, a positive allosteric modulator. In certain embodiments of the present disclosure, a pet food product can be produced that contains a sufficient amount of at least one flavor composition described herein, for example, comprising a compound of Table 1, to produce a pet food product having the desired taste, e.g., kokumi. In certain embodiments of the present disclosure, a pet food product can be produced that contains a sufficient amount of a flavor composition comprising at least one, two, three, four, five, six or more compounds. In certain non-limiting embodiments, the present disclosure provides for a method of increasing the palatability of a pet food product comprising admixing the pet food product with a flavor composition as described herein, wherein the flavor composition is present at a concentration of from about 1 nM to about 10 M, or from about 1 nM to about 1 M in the admixture. In certain non-limiting embodiments, the present disclosure provides for a method of increasing the taste of a pet food product, comprising admixing the pet food product with a flavor composition as described herein, wherein the flavor composition is present at a concentration of from about 0.001 ppm to about 1,000 ppm in the admixture. In certain non-limiting embodiments, the present disclosure provides for a method of increasing the taste of a pet food product, comprising admixing the pet food product with a flavor composition as described herein, wherein the flavor composition is present at a concentration of from about 0.0001% to about 10% w/w, or from about 0.001% to about 5% w/w, or from about 0.01% to about 1% w/w in the admixture. In certain non-limiting embodiments, the present disclosure provides for a method of increasing the palatability of a pet food product comprising admixing the pet food product with a Active 118427983.2 33 069269.0689 PATENT compound as described herein, wherein the compound is present at a concentration of from about 1 nM to about 10 M, or from about 1 nM to about 1 M in the product. In certain non-limiting embodiments, the present disclosure provides for a method of increasing the palatability of a pet food product comprising admixing the pet food product with a compound as described herein, wherein the compound is present at a concentration of from about 0.001 ppm to about 1,000 ppm in the admixture. In certain non-limiting embodiments, the present disclosure provides for a method of increasing the palatability of a pet food product comprising admixing the pet food product with a compound as described herein, wherein the compound is present at a concentration of from about 0.0001% to about 10% w/w, or from about 0.001% to about 5% w/w, or from about 0.01% to about 1% w/w in the admixture. 6. Delivery Systems In certain embodiments, the compounds and/or flavor compositions of the present application can be incorporated into a delivery system for use in pet food products. Delivery systems can be liquid or solid, aqueous or non-aqueous. Delivery systems are generally adapted to suit the needs of the compound, flavor composition and/or the pet food product into which the compound and/or flavor composition will be incorporated. The compounds and/or flavoring compositions can be employed in liquid form, dried form and/or solid form. When used in dried form, suitable drying means such as spray drying can be used. Alternatively, a compound and/or a flavoring composition can be encapsulated or absorbed onto water soluble materials, including but not limited to materials such as cellulose, starch, sugar, maltodextrin, gum arabic and so forth. The actual techniques for preparing such dried forms are well-known in the art, and can be applied to the presently disclosed subject matter. The compounds and/or flavor compositions of the presently disclosed subject matter can be used in many distinct physical forms well known in the art to provide an initial burst of taste, flavor and/or texture; and/or a prolonged sensation of taste, flavor and/or texture. Without being limited thereto, such physical forms include free forms, such as spray dried, powdered, and beaded forms, and encapsulated forms, and mixtures thereof. In certain embodiments, compounds can be generated during processing of the pet food. For example, and not by way of limitation, the compounds can be generated from precursor compounds during thermal processing, e.g., retorting, extrusion and/or sterilization, of the pet food. In certain embodiments, as noted above, encapsulation techniques can be used to modify the flavor systems. In certain embodiments, flavor compounds, flavor components or the entire Active 118427983.2 34 069269.0689 PATENT flavor composition can be fully or partially encapsulated. Encapsulating materials and/or techniques can be selected to determine the type of modification of the flavor system. In certain embodiments, the encapsulating materials and/or techniques are selected to improve the stability of the compounds, flavor components or flavor compositions; while in other embodiments, the encapsulating materials and/or techniques are selected to modify the release profile of the flavor compositions. Suitable encapsulating materials can include, but are not limited to, hydrocolloids such as alginates, pectins, agars, guar gums, celluloses, and the like, proteins, polyvinyl acetate, polyethylene, crosslinked polyvinyl pyrrolidone, polymethylmethacrylate, polylactidacid, polyhydroxyalkanoates, ethylcellulose, polyvinyl acetatephthalate, polyethylene glycol esters, methacrylicacid-co-methylmethacrylate, ethylene-vinylacetate (EVA) copolymer, and the like, and combinations thereof. Suitable encapsulating techniques can include, but are not limited to, spray coating, spray drying, spray chilling, absorption, adsorption, inclusion complexing (e.g., creating a flavor/cyclodextrin complex), coacervation, fluidized bed coating or other processes that can be used to encapsulate an ingredient with an encapsulating material. Encapsulated delivery systems for flavoring agents or sweetening agents can contain a hydrophobic matrix of fat or wax surrounding a sweetening agent or flavoring agent core. The fats can be selected from any number of conventional materials such as fatty acids, glycerides or poly glycerol esters, sorbitol esters, and mixtures thereof. Examples of fatty acids include but are not limited to hydrogenated and partially hydrogenated vegetable oils such as palm oil, palm kernel oil, peanut oil, rapeseed oil, rice bran oil, soybean oil, cottonseed oil, sunflower oil, safflower oil and combinations thereof. Examples of glycerides include, but are not limited to, monoglycerides, diglycerides and triglycerides. Waxes can be chosen from the group consisting of natural and synthetic waxes and mixtures thereof. Non-limiting examples include paraffin wax, petrolatum, carbowax, microcrystalline wax, beeswax, carnauba wax, candellila wax, lanolin, bayberry wax, sugarcane wax, spermaceti wax, rice bran wax, and mixtures thereof. The fats and waxes can be use individually or in combination in amounts varying from about 10 to about 70%, and alternatively in amounts from about 30 to about 60%, by weight of the encapsulated system. When used in combination, the fat and wax can be present in a ratio from about 70:10 to 85:15, respectively. Typical encapsulated flavor compositions, flavoring agent or sweetening agent delivery systems are disclosed in U.S. Patent Nos.4,597,970 and 4,722,845, the disclosures of which are incorporated herein by reference in their entireties. Active 118427983.2 35 069269.0689 PATENT Liquid delivery systems can include, but are not limited to, systems with a dispersion of the flavor compositions of the present application, such as in carbohydrate syrups and/or emulsions. Liquid delivery systems can also include extracts where the nucleotide derivative, transmembrane compound, and/or the flavor compositions are solubilized in a solvent. Solid delivery systems can be created by spray drying, spray coating, spray chilling, fluidized bed drying, absorption, adsorption, coacervation, complexation, or any other standard technique. In some embodiments, the delivery system can be selected to be compatible with or to function in the edible composition. In certain embodiments, the delivery system will include an oleaginous material such as a fat or oil. In certain embodiments, the delivery system will include a confectionery fat such as cocoa butter, a cocoa butter replacer, a cocoa butter substitute, or a cocoa butter equivalent. When used in dried form, suitable drying means such as spray drying can be used. Alternatively, a compound or a flavoring composition can be adsorbed or absorbed onto substrates such as water soluble materials, such as cellulose, starch, sugar, maltodextrin, gum arabic and so forth can be encapsulated. The actual techniques for preparing such dried forms are well known in the art. 7. Methods of Measuring Taste Attributes In certain embodiments of the present disclosure, the taste, flavor and/or palatability attributes of a pet food product can be modified by admixing a compound with the food product, or generated under food preparation conditions, as described herein. In certain embodiments, the taste, flavor and/or palatability attributes of a pet food product can be modified by admixing a flavor composition with the food product, or generated under food preparation conditions, as described herein. In certain embodiments, the attribute(s) can be enhanced or reduced by increasing or decreasing the concentration of the compound and/or flavor composition admixed or generated with the food product. In certain embodiments, the taste attributes of the modified food product can be evaluated as described herein, and the concentration of compound and/or flavor composition admixed or generated with the food product can be increased or decreased based on the results of the evaluation. In certain embodiments of the present disclosure, the taste and/or palatability attributes can be measured using an in vitro assay, wherein a compound’s ability to activate a GPRC6A receptor expressed by cells in vitro at different concentrations is measured. In certain embodiments, the in vitro assay comprises the in vitro assays described in Section 3 and in the Examples of the present application. Active 118427983.2 36 069269.0689 PATENT In certain embodiments of the present disclosure, the taste and/or palatability attributes can be measured using a panelist of taste testers. For example, but not by way of limitation, the panel can contain feline panelists. In certain embodiments, the panel can include canine panelists. In certain embodiments, the palatability of a pet food product can be determined by the consumption of a pet food product containing a flavor composition alone (e.g., the one bowl test, monadic ranking). In certain embodiments, the palatability of a pet food product can be determined by the preferential consumption of a pet food product containing a flavor composition, disclosed herein, versus a pet food product that does not contain the flavor composition or another flavor composition (e.g., the two bowl test for testing preference, difference and/or choice). In certain embodiments, the palatability and/or taste of a flavor composition can be determined by the preferential consumption of a water solution containing a flavor composition, disclosed herein, versus a water solution that does not contain the flavor composition or contains a different flavor composition (e.g., the two bottle test). For example, a solution panel can be used to compare the palatability of a range of concentrations of compounds in a monadic exposure. In certain embodiments, the solution can contain a palatability enhancer, for example, L-histidine, as an ingestive/positive tastant to increase baseline solution intake, therefore enabling the identification of a potential negative impact of the test compound. The intake ratio for each pet food product or water solution can be determined by measuring the amount of one ration consumed divided by the total consumption. The consumption ratio (CR) can then be calculated to compare the consumption of one ration in terms of the other ration to determine the preferential consumption of one food product or water solution over the other. Alternatively or additionally, the difference in intake (g) can be used to assess the average difference in intake between the two solutions in a two bottle test or between two pet food products in a two bowl test at a selected significance level, for example, at the 5% significance level to determine an average difference in intake with a 95% confidence interval. However, any significance level can be used, for example, a 1, 2, 3, 4, 5, 10, 15, 20, 25, or 50% significance level. In certain embodiments, percentage preference scores, e.g., the percentage preference for one solution or food product by an animal is the percentage of the total liquid or food product ingested during the test that that solution or food product accounts for, can also be calculated. 8. Exemplary Embodiments Clause 1. A pet food product comprising: (a) one or more compounds that bind to a GPRC6A receptor or a functional fragment thereof; or (b) a flavor composition comprising one or more compounds that bind to a GPRC6A receptor or a functional fragment thereof. Clause 2. The pet food product of clause 1, wherein the pet food product has enhanced palatability. Active 118427983.2 37 069269.0689 PATENT Clause 3. The pet food product of clause 1 or 2, wherein the one or more compound increases, decreases or modulates the biological activity of the GPRC6A receptor. Clause 4. The pet food product of any one of clauses 1-3, wherein the one or more compound is selected from the group consisting of amino acids, peptides, hormones, ions, metals, butanoic acid-based compounds, propanoic acid-based compounds, pentanoic acid-based compounds, carboxylic acid-based compounds, derivatives thereof, and combinations thereof. Clause 5. The pet food product of any one of clauses 1-4, wherein the one or more compound has an EC50 value of no more than about 50 mM in connection with a biological activity of the GPRC6A receptor. Clause 6. The pet food product of any one of clauses 1-5, wherein the compound has the formula: . Clause 7. The pet food product of clause 6, wherein R1 is selected from the group consisting of H, C1-C20 alkyl, branched C1-C20 alkyl, unbranched C1-C20 alkyl, C1-C20 alkenyl, brached C1-C20 alkenyl, unbranched C1-C20 alkenyl, C1-C20 alkynyl, branched C1- C20 alkynyl, unbranched C1-C20 alkynyl, arylalkyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, heteroarylalkyl, haloalkyl, CF3, halogen, phenyl, -C(O)R3, -COOR3, -NR3R4, -NO2, -OH, - OR3, -CONR3R4, -S-Aryl, -O-Aryl, -N-Aryl, -NO2, -SO3H, -SO2R3, -NHOH, -C=CR3, - C=NOH, -OP(O)(OH)2, and CHO. Clause 8. The pet food product of clause 7, wherein R3 and R4 are each independently selected from the group consisting of H, C1-C20 alkyl, branched C1-C20 alkyl, unbranched C1- C20 alkyl, C1-C20 alkenyl, brached C1-C20 alkenyl, unbranched C1-C20 alkenyl, C1-C20 alkynyl, branched C1-C20 alkynyl, unbranched C1-C20 alkynyl, arylalkyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, heteroarylalkyl, haloalkyl, CF3, and halogen. Clause 9. The pet food product of any one of clauses 6-8, wherein R1 is substituted. Clause 10. The pet food product of any one of clauses 6-9, wherein R2 is selected from the group consisting of H, C1-C20 alkyl, branched C1-C20 alkyl, unbranched C1-C20 alkyl, C1- C20 alkenyl, brached C1-C20 alkenyl, unbranched C1-C20 alkenyl, C1-C20 alkynyl, branched C1-C20 alkynyl, unbranched C1-C20 alkynyl, arylalkyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, and heteroarylalkyl. Clause 11. The pet food product of any one of clauses 6-10, wherein R2 is H or methyl. Clause 12. The pet food product of any one of clauses 1-5, wherein the compound has the formula: DRAWING. Clause 13. The pet food of clause 12, wherein R is selected from the group consisting of H, C1-C20 alkyl, branched C1-C20 alkyl, unbranched C1-C20 alkyl, C1-C20 alkenyl, brached C1-C20 alkenyl, unbranched C1-C20 alkenyl, C1-C20 alkynyl, branched C1-C20 alkynyl, Active 118427983.2 38 069269.0689 PATENT unbranched C1-C20 alkynyl, arylalkyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, heteroarylalkyl, haloalkyl, CF3, halogen, phenyl, -C(O)R3, -COOR3, -NR3R4, -NO2, -OH, -OR3, -CONR3R4, - S-Aryl, -O-Aryl, -N-Aryl, -NO2, -SO3H, -SO2R3, -NHOH, -C=CR3, -C=NOH, -OP(O)(OH)2, and CHO. Clause 14. The pet food product of clause 13, wherein R1 and R2 are each independently selected from the group consisting of H, C1-C20 alkyl, branched C1-C20 alkyl, unbranched C1- C20 alkyl, C1-C20 alkenyl, brached C1-C20 alkenyl, unbranched C1-C20 alkenyl, C1-C20 alkynyl, branched C1-C20 alkynyl, unbranched C1-C20 alkynyl, arylalkyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, heteroarylalkyl, haloalkyl, CF3, and halogen. Clause 15. The pet food product of any one of clauses 12-14, wherein R is substituted. Clause 16. The pet food product of any one of clauses 6-15, wherein the compound comprises: (a) includes an L-amino-acid; (b) includes one carbon after the ^^-carbon of the amino- acid unit; (c) can include a positively-charged group at a distance up to ~9A from the ^^-carbon (alpha carbon denoting the carbon of the compound to the amino group to the carboxyl group); and/or (d) does not include a negatively-charged group at a distance up to ~9A from ^^-carbon. Clause 17. The pet food product of any one of clauses 1-16, wherein the one or more compound is present at a concentration of between about 0.0001% and about 2% weight/weight (w/w) in the pet food product. Clause 18. The pet food product of any one of clauses 1-16, wherein the flavor composition is present at a concentration of between about 0.0001% and about 2% weight/weight (w/w) in the pet food product. Clause 19. The pet food product of any one of clauses 1-16, wherein the one or more compound is present at a concentration of between about 0.00001% and about 5% in the flavor composition. Clause 20. The pet food product of any one of clauses 1-19, wherein the GPRC6A receptor is a feline GPRC6A receptor. Clause 21. The pet food product of any one of clauses 1-19, wherein the GPRC6A receptor is a canine GPRC6A receptor. Clause 22. A method for increasing palatability of a pet food product, the method comprising providing a pet food product; and (a) admixing the pet food product with at least one compound that binds to one or more amino acids of a GPRC6A receptor; or (b) admixing the pet food product with at least one flavor composition, wherein the flavor composition comprises a compound that binds to one or more amino acids of a GPRC6A receptor. Clause 23. The method of clause 22, wherein the at least one compound is selected from the group consisting of amino acids, peptides, hormones, ions, metals, butanoic acid-based Active 118427983.2 39 069269.0689 PATENT compounds, propanoic acid-based compounds, pentanoic acid-based compounds, carboxylic acid- based compounds, derivates thereof, and combinations thereof. Clause 24. The method of clause 22 or 23, wherein the compound has the formula: . Clause 25. The method of clause 24, wherein R1 is selected from the group consisting of H, C1-C20 alkyl, branched C1-C20 alkyl, unbranched C1-C20 alkyl, C1-C20 alkenyl, brached C1-C20 alkenyl, unbranched C1-C20 alkenyl, C1-C20 alkynyl, branched C1-C20 alkynyl, unbranched C1-C20 alkynyl, arylalkyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, heteroarylalkyl, haloalkyl, CF3, halogen, phenyl, -C(O)R3, -COOR3, -NR3R4, -NO2, -OH, -OR3, -CONR3R4, - S-Aryl, -O-Aryl, -N-Aryl, -NO2, -SO3H, -SO2R3, -NHOH, -C=CR3, -C=NOH, -OP(O)(OH)2, and CHO. Clause 26. The method of clause 25, wherein R3 and R4 are each independently selected from the group consisting of H, C1-C20 alkyl, branched C1-C20 alkyl, unbranched C1-C20 alkyl, C1-C20 alkenyl, brached C1-C20 alkenyl, unbranched C1-C20 alkenyl, C1-C20 alkynyl, branched C1-C20 alkynyl, unbranched C1-C20 alkynyl, arylalkyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, heteroarylalkyl, haloalkyl, CF3, and halogen. Clause 27. The method of any one of clauses 24-26, wherein R1 is substituted. Clause 28. The method of any one of clauses 24-27, wherein R2 is selected from the group consisting of H, C1-C20 alkyl, branched C1-C20 alkyl, unbranched C1-C20 alkyl, C1-C20 alkenyl, brached C1-C20 alkenyl, unbranched C1-C20 alkenyl, C1-C20 alkynyl, branched C1- C20 alkynyl, unbranched C1-C20 alkynyl, arylalkyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, and heteroarylalkyl. Clause 29. The method of any one of clauses 24-28, wherein R2 is H or methyl. Clause 30. The method of clause 22 or 23, wherein the compound has the formula: DRAWING. Clause 31. The method of clause 30, wherein R is selected from the group consisting of H, C1-C20 alkyl, branched C1-C20 alkyl, unbranched C1-C20 alkyl, C1-C20 alkenyl, brached C1-C20 alkenyl, unbranched C1-C20 alkenyl, C1-C20 alkynyl, branched C1-C20 alkynyl, unbranched C1-C20 alkynyl, arylalkyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, heteroarylalkyl, haloalkyl, CF3, halogen, phenyl, -C(O)R3, -COOR3, -NR3R4, -NO2, -OH, -OR3, -CONR3R4, - S-Aryl, -O-Aryl, -N-Aryl, -NO2, -SO3H, -SO2R3, -NHOH, -C=CR3, -C=NOH, -OP(O)(OH)2, and CHO. Clause 32. The method of clause 31, wherein R1 and R2 are each independently selected from the group consisting of H, C1-C20 alkyl, branched C1-C20 alkyl, unbranched C1-C20 alkyl, C1-C20 alkenyl, brached C1-C20 alkenyl, unbranched C1-C20 alkenyl, C1-C20 alkynyl, Active 118427983.2 40 069269.0689 PATENT branched C1-C20 alkynyl, unbranched C1-C20 alkynyl, arylalkyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, heteroarylalkyl, haloalkyl, CF3, and halogen. Clause 33. The method of any one of clauses 30-32, wherein R is substituted. Clause 34. The method of any one of clauses 24-33, wherein the compound comprises: (a) includes an L-amino-acid; (b) includes one carbon after the ^^-carbon of the amino-acid unit; (c) can include a positively-charged group at a distance up to ~9A from the ^^-carbon (alpha carbon denoting the carbon of the compound to the amino group to the carboxyl group); and/or (d) does not include a negatively-charged group at a distance up to ~9A from ^^-carbon. Clause 35. The method of any one of clauses 22-34, wherein the at least one compound binds to one or more amino acids of a Venus Flytrap Domain of the GPRC6A receptor. Clause 36. The method of any one of clauses 22-35, wherein the least one compound binds to one or more amino acids of a 7-transmembrane domain of the GPRC6A receptor. Clause 37. The method of any one of clauses 22-36, wherein the GPRC6A receptor is a feline GPRC6A. Clause 38. The method of clause 37, wherein the at least one compound binds to one or more amino acids of the feline GPRC6A receptor selected from the group consisting of Tyr148, Ser149, Glu170, Thr172, Asp 218, Tyr220, Arg279, Asp303, Asn304, Thr307, Arg399, Asn400, and combination thereof. Clause 39. The method of clause 37 or 38, wherein the compound binds to one or more amino acids of the feline GPRC6A receptor selected from the group consisting of Arg662, Gln663, Phe666, Gly667, Phe670, Gln715, Glu746, Ala751, Phe752, Met755, Leu756, Ile759, Tyr793, Trp797, Phe800, Tyr804, Glu816, Val819, Ile820, and combinations thereof. Clause 40. The method of any one of clauses 22-36, wherein the GPRC6A receptor is a canine GPRC6A. Clause 41. The method of clause 40, wherein the at least one compound binds to one or more amino acids of the canine GPRC6A receptor selected from the group consisting of Tyr148, Ser149, Glu170, Thr172, Asp 218, Tyr220, Arg279, Asp303, Asn304, Met307, Arg399, Asn400, and combination thereof. Clause 42. The method of clause 40 or 41, wherein the compound binds to one or more amino acids of the GPRC6A receptor selected from the group consisting of Arg662, Gln663, Phe666, Gly667, Phe670, Gln715, Glu746, Ala751, Phe752, Met755, Leu756, Ile759, Tyr793, Trp797, Phe800, Tyr804, Glu816, Val819, Ile820, and combinations thereof. Clause 43. The method of any one of clauses 22-42, wherein the at least one compound is present at a concentration of between about 0.0001% and about 2% in the pet food product. Active 118427983.2 41 069269.0689 PATENT Clause 44. The method of any one of clauses 22-42, wherein the flavor composition is present at a concentration of between about 0.001% and about 2% in the pet food product. Clause 45. The method of any one of clauses 22-42, wherein the at least one compound is present at a concentration of between about 0.00001% and about 5% in the flavor composition. Clause 46. The method of any one of clauses 22-45, wherein the method comprises thermal processing of a food product precursor, wherein the compound is generated during the thermal processing. EXAMPLES The presently disclosed subject matter will be better understood by reference to the following Examples, which are provided as exemplary of the invention, and not by way of limitation. Example 1 – Compound profiling. The present example provides for the primary profiling and activity determination combined in a single experiment. Full concentration-response curves of all compounds were done at eight concentrations in quadruplicate on fGPRC6A expressing and non-expressing cells. L- Arginine was used as a reference activator for fGPRC6A. Materials and Methods Cell lines, media and culture conditions. The experiments were done using the HEK293 T-Rex cells stably expressing fGPRC6A and the G protein GαqG66D. HEK293 T-Rex cells only expressing GαqG66D served as a negative control (mock). HEK-293 T- REx/natClytin/fGPRC6A+ GαqG66D K2.3 was cultured in medium DMEM High Glucose (Lonza BioWhittaker cat. BE12-604F/U1; 500mL) supplemented with 10% Fetal Bovine Serum TET-FREE (Euroclone cat. EC S0182L), 1% Penicillin-Streptomycin (BioWhittaker cat. DE17- 602E), 1.25 µg/ml Blasticidin, 0.2 µg/mL Puromycin, 17.5 µg/mL Hygromycin B, 0.2 mg/mL G418. HEK-293 T-REx/natClytin/GαqG66D K3 was cultured in medium DMEM High Glucose (Lonza BioWhittaker cat. BE12-604F/U1; 500mL) supplemented with 10% Fetal Bovine Serum TET-FREE (Euroclone cat. EC S0182L), 1% Penicillin-Streptomycin (BioWhittaker cat. DE17- 602E), 1.25 µg/ml Blasticidin, 0.2 µg/mL Puromycin, 0.4 mg/mL G418. Cells were split every 3-4 days by a gentle wash with PBS, followed by 5 min incubation at 37°C with Trypsin. Detached cells were diluted with complete medium and counted using the BECKMAN COULTER Z1TM Particle Counter. The desired number of cells was plated into a new flask or used for adherent experiments. Active 118427983.2 42 069269.0689 PATENT Assay protocol. Experimental activities were performed using a Fluorescence Plate Reader (FLIPRTETRA, Molecular Devices). Additional equipment included the automatic dispensing/diluting device IGEL (Opaljena/CyBio) and the Microplate Washer (BioTek Instruments). Experiments were carried out in black-clear bottom poly-D-Lysine coated 384 well plates (Thermo Scientific, MATRIX cat. GR-4332 CPL). Compound dilutions were performed in 384-well polypropylene V-bottom plates (Greiner bio-one, cat.781280). Cells were incubated 3 h at RT with Cal520-AM dye. After the incubation step, the dye is removed and replaced by standard Tyrode’s buffer by using the Microplate washer, followed by 15 min incubation at RT. After the incubation step, Tyrode’s buffer is removed and replaced with fresh standard Tyrode’s buffer by using the Microplate washer. Plates were then analyzed at FLIPRTETRA using a λ exc 470 - 495 nm / λ em 515 - 575 nm filter. The instrument settings of Excitation Intensity and Gate were regulated in order to obtain basal fluorescence values around 10,000 RFU, then cells were injected with the compounds (first injection: 10 μL/well of 3X compounds; second injection: 10 μL/well, 4X) and fluorescence was measured at FLIPRTETRA usually for three minutes. Data analysis. FLIPRTETRA measurements were analyzed with Screenworks© software (Molecular Devices, Version 4.0.0.30). For Cal520-AM fluorescence experiments, cellular responses were normalized to the fluorescence value prior to the stimulus (ΔF/F0). Normalized data were exported from Screenworks© software, and used in Excel to calculate mean and standard deviation of well replicates for each condition. The obtained values were then used to fit sigmoidal dose-response curves with GraphPad® Prism7 software (variable slope) and to obtain EC50 values for the tested compounds. Compound profiling methods. For the compound profiling experiments, the compounds were tested in a double injection protocol at 8 concentration points in quadruplicate. The compound dilutions were 3.162 fold (1/2-log step) starting from the maximum concentration as indicated in Table 2. Table 2. max. not compound name concentration completely [mM] dissolved (2R)-2-amino-3-methanesulfonylpropanoic acid 10 (2S)-2-amino-4-(ethylcarbamoyl)butanoic acid 1 (2S)-2-amino-5-(benzyloxy)-5-oxopentanoic acid 10 x (2S)-2-amino-5-(tert-butoxy)-5-oxopentanoic acid 1 x (2S)-2-amino-5-{[(benzyloxy)carbonyl]amino}pentanoic a_cid ^{10 x} (2S,3R)-2-amino-3-methoxybutanoic acid, O-methyl t_hreonine ¹⁰ Active 118427983.2 43 069269.0689 PATENT max. not compound name concentration completely [mM] dissolved L-Canavanine 0.3 2-amino-2-cyclopentylacetic acid 10 x 2-amino-3-(methylthio)propanoic acid, S-methyl cysteine 10 2-amino-3-(piperidin-1-yl)propanoic acid _{dihydrochloride} ¹⁰ 2-amino-3-[(2-methoxy-2-oxoethyl)sulfanyl]propanoic _acid ¹⁰ 2-amino-3-[(4-aminophenyl)sulfanyl]propanoic acid 10 x 2-amino-3-[benzyl(methyl)amino]propanoic acid 10 x 2-amino-3-[methyl(phenyl)amino]propanoic acid 10 x 2-amino-3-carbamimidamido propanoic acid 1 2-amino-3-cyclobutylpropanoic acid hydrochloride[HCl] 10 x 2-amino-3-methoxypropanoic acid hydrochloride, O- _{methyl serine} ¹⁰ 2-amino-4-oxo-4-(thiophen-2-yl)butanoic acid _{hydrochloride} ^{10 x} 2-amino-4-oxo-4-phenylbutanoic acid hydrochloride 1 x 3-(2-Thienyl)-L-alanine 10 L-Alanine 3 aminoisobutyric acid 10 L-Arginine 10 L-Asparagine 10 Calcium chloride 10 D-Arginine 10 Dl-2,3-diaminopropionic acid HCl 10 DL-5-Hydroxylysine hydrochloride 0.3 Gadolinium ion 1 L-Glutamine 10 Glycine 3 H-ASP(OBZL)-OH 1 x L-Histidine 10 Homoserine, (S)-2-Amino-4-hydroxybutyric acid, Hse 10 L-Isoleucine 10 L-4-Thialysine hydrochloride 10 L-Arginine 1 L-BMAA hydrochloride, S(+)-2-Amino-3- _{(methylamino)propionic acid hydrochloride} ¹⁰ L-Carnosine 10 L-Citrulline 1 L-Cysteine 10 L-Ethionine 10 L-Homoargininie 0.3 L-Homocysteine 10 Active 118427983.2 44 069269.0689 PATENT max. not compound name concentration completely [mM] dissolved L-Leucine 10 L-Methionine sulfoxide 10 L-NAME hydrochloride 0.1 L-Norvaline, (S)-(+)-2-Aminopentanoic acid, (S)-2- A_{minovaleric acid} ¹⁰ L-Ornithine 1 L-Tyrosine 10 x L-Valine 10 L-Lysine 3 L-Methionine 10 methyl (2S)-2-amino-3-[(5-chlorothiophen-2- y_{l)formamido]propanoate hydrochloride} ¹⁰ methyl 2-amino-4-(piperidin-1-yl)butanoate d_{ihydrochloride} ¹ methyl 2-amino-4-carbamoylbutanoate 10 N^G,N^G-Dimethylarginine dihydrochloride 0.3 N^G-amino-L-Arginine (hydrochloride) 0.3 NG-Hydroxy-L-arginine, Monoacetate Salt 0.3 N^G-Methyl-L-arginine acetate salt 0.3 nor-NOHA (acetate) 1 N_ω-Nitro-L-arginine 0.1 x L-Phenylalanine 10 Praesodymium (III) trifluromethane sulfonate 1 Se-(Methyl)selenocysteine 10 L-Serine 10 Strontium hydroxide 10 x Terbium (III) acetate hydrate 1 L-Threonine 10 L-Tryptophan 10 L-Valine 10 Compounds were solubilized in Tyrode’s buffer containing 30 mM MgCl2 (3x concentrated). Some of the compounds showed precipitation issues in Tyrode’s buffer (see Table 2). Results fGPR6CA expressing and non-expressing cells were stimulated with increasing concentrations of Carbachol and L-Arg + 20 mM MgCl₂ in the presence of different DMSO concentrations. Moreover, fGPRC6A expressing cells were stimulated with increasing concentrations of L-Arg, MgCl2 and DMSO in the presence of fixed concentrations of L-Arg, DMSO or MgCl₂. In all cases a co-injection and a sequential application protocol was used. Active 118427983.2 45 069269.0689 PATENT During the assay development, a markedly increased sensitivity of the assay towards L-Arginine was determined (Figures 1A-1D). Further, experiments were repeated including Carbachol as a fGPRC6A independent cellular stimulus (Figures 1A-1D). To elucidate the different interactions of L-Arginine and MgCl2 with fGPRC6A, increasing concentrations of each compound were combined in the absence and presence of a fixed concentration of the other compounds (Figures 2A and 2B). DMSO was used as control condition. Application of both compounds had the biggest effect on fGPRC6A activity. The profiling of the compounds was performed by incubating the test compounds with 10mM MgCl_2. The presence of 10 mM MgCl₂ enhanced the responsiveness of fGPRC6A and thus allowed detection of less potent agonists during the assay and also to enhance the responsiveness of the whole system. fGPRC6A non expressing cells were used to record unspecific activity of the compounds. From the tested compounds, 71 compounds had agonistic activity. Figures 3A-3F show a representative example of compounds with agonistic activity. The EC50 values of the agonistic activity of each compound is indicated in Table 3. Table 3 compound name ^EC50 [_mM] (2R)-2-amino-3-methanesulfonylpropanoic acid 0.18 (2S)-2-amino-4-(ethylcarbamoyl)butanoic acid 0.1 (2S)-2-amino-5-(benzyloxy)-5-oxopentanoic acid 0.04 (2S)-2-amino-5-(tert-butoxy)-5-oxopentanoic acid 0.05 (2S)-2-amino-5-{[(benzyloxy)carbonyl]amino}pentanoic acid >10 (2S,3R)-2-amino-3-methoxybutanoic acid, O-methyl threonine >10 L-Canavanine 0.02 2-amino-2-cyclopentylacetic acid >3 2-amino-3-(methylthio)propanoic acid, S-methyl cysteine 0.64 2-amino-3-(piperidin-1-yl)propanoic acid dihydrochloride >1 2-amino-3-[(2-methoxy-2-oxoethyl)sulfanyl]propanoic acid 0.59 2-amino-3-[(4-aminophenyl)sulfanyl]propanoic acid 0.07 2-amino-3-[benzyl(methyl)amino]propanoic acid >3 2-amino-3-[methyl(phenyl)amino]propanoic acid >3 2-amino-3-carbamimidamido propanoic acid 0.02 2-amino-3-cyclobutylpropanoic acid hydrochloride[HCl] 0.07 2-amino-3-methoxypropanoic acid hydrochloride, O-methyl serine 0.18 2-amino-4-oxo-4-(thiophen-2-yl)butanoic acid hydrochloride 0.05 2-amino-4-oxo-4-phenylbutanoic acid hydrochloride 0.2 3-(2-Thienyl)-L-alanine 3.5 Active 118427983.2 46 069269.0689 PATENT compound name ^EC50 [_mM] L-Alanine 0.1 aminoisobutyric acid > 10 L-Arginine 0.02 L-Asparagine 1.6 Calcium chloride > 10 D-Arginine > 3 Dl-2,3-diaminopropionic acid HCl 0.06 DL-5-Hydroxylysine hydrochloride 0.03 Gadolinium ion > 0.3 L-Glutamine 0.3 Glycine 0.07 H-ASP(OBZL)-OH 0.08 L-Histidine >3 Homoserine, (S)-2-Amino-4-hydroxybutyric acid, Hse 0.21 L-Isoleucine 3.6 L-4-Thialysine hydrochloride 0.06 L-Arginine 0.02 L-BMAA hydrochloride, S(+)-2-Amino-3-(methylamino)propionic acid hydrochloride 0.07 L-Carnosine > 10 L-Citrulline 0.07 L-Cysteine 0.26 L-Ethionine 0.2 L-Homoargininie 0.03 L-Homocysteine 0.6 L-Leucine 3.64 L-Methionine sulfoxide 1.08 L-NAME hydrochloride 0.006 L-Norvaline, (S)-(+)-2-Aminopentanoic acid, (S)-2-Aminovaleric acid 0.34 L-Ornithine 0.07 L-Tyrosine 4.4 L-Valine 3.8 L-Lysine 0.2 L-Methionine 0.4 methyl 2-amino-4-(piperidin-1-yl)butanoate dihydrochloride 0.02 methyl 2-amino-4-carbamoylbutanoate >0.3 N^G,N^G-Dimethylarginine dihydrochloride 0.01 N^G-amino-L-Arginine (hydrochloride) 0.02 NG-Hydroxy-L-arginine, Monoacetate Salt 0.003 N^G-Methyl-L-arginine acetate salt 0.03 nor-NOHA (acetate) 0.02 Nω-Nitro-L-arginine 0.001 L-Ornithine 0.03 Active 118427983.2 47 069269.0689 PATENT compound name ^EC50 [_mM] L-Phenylalanine 4.3 Praesodymium (III) trifluromethane sulfonate > 0.3 Se-(Methyl)selenocysteine 0.1 L-Serine 0.2 Strontium hydroxide > 1 Terbium (III) acetate hydrate > 0.3 L-Threonine 0.7 L-Tryptophan 2.1 L-Valine > 3 Conclusions The activity of several compounds was determined in the presence of MgCl2 to identify also less potent agonists. Several compounds showed agonistic activities having different potencies. The obtained EC50 values, indicated in Table 3, ranged from low micromolar to higher millimolar values. Example 2 – In silico identification of feline GPRC6A receptor agonists. In vitro functional characterization was used to evaluate the effectiveness of the putative agonist compounds in modulating the activation of a GPRC6A receptor. Computational approaches were used to analyze the three-dimensional structure of the Feline GPRC6A receptor to identify polypeptide regions that can be exploited to selectively modulate the GPRC6A receptor. The GPCR group C family of proteins includes GPRC6A, T1R1, T1R2, T1R3, CaSR, GabaB, and mGlu proteins. Group C proteins have (1) a large external domain, called a Venus Flytrap (VFT) domain, (2) a 7 Transmembrane (7TM) domain, and (3) a cysteine-rich domain that connects the VFT and the 7TM domains. A structural homology model of the Venus Flytrap domain of the GPRC6A receptor was generated based on the structure of Venus Flytrap domain of the human CaSR receptor, 5K5S (Geng et al. Structural mechanism of ligand activation in human calcium-sensing receptor.2016. Elife 5) from the Protein Data Bank (PDB). (Berman et al., Nucleic Acids Research, 28: 235-242 (2000), which is incorporated by reference herein in its entirety). Feline VFT GPCR6A has a ~31% sequence identity to human VFT of CaSR. The homology models were built using the I- TASSER suite of programs (see Yang et al., Nature Methods, 12: 7-8 (2015), which is incorporated by reference herein in its entirety) and the Modeller software package (see Eswar et al., Curr Protoc Bioinformatics, John Wiley & Sons, Inc., Supplement 15, 5.6.1-5.6.30 (2006), Active 118427983.2 48 069269.0689 PATENT which is incorporated by reference herein in its entirety) from the DiscoveryStudio (DS) suite of programs from Dassault Systemes (BIOVIA Corp., San Diego, CA, USA). The docking program, BioDock, from BioPredict, was used to dock the compounds into the active site of the VFT domain of GPRC6A, in silico, as shown in Figures 4B and 4C and 5B and 5C. Residues lining the active site of feline GPRC6A Venus Flytrap domain include Tyr148, Ser149, Glu170, Thr172, Asp218, Tyr220, Arg279, Asp303, Asn304, Thr307, Arg399, Asn400. Those amino acids played critical roles in the homology models by forming salt-bridges, hydrogen-bonding, and hydrophobic interactions to co-ordinate the charged groups and polar parts of compounds bound to the active site. Standard proteogenic amino acids are almost all active. Further, based on these GPRC6A models and docking of the ligands, the following motif was predicted as being a “GPRC6A-VFT- ACTIVE-MOTIF” able to activate a GPRC6A receptor: i. includes an L-amino-acid; ii. includes one carbon after the ^^-carbon of the amino-acid unit; iii. can include a positively-charged group at a distance up to ~9A from the ^^-carbon (alpha carbon denoting the carbon of the compound to the amino group to the carboxyl group); and iv. does not include a negatively-charged group at a distance up to ~9A from ^^-carbon. * * * Although the presently disclosed subject matter and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the presently disclosed subject matter, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein can be utilized according to the presently disclosed subject matter. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps. Active 118427983.2 49 069269.0689 PATENT Patents, patent applications, publications, product descriptions and protocols are cited throughout this application the disclosures of which are incorporated herein by reference in their entireties for all purposes. Active 118427983.2 50

Claims

069269.0689 PATENT WHAT IS CLAIMED IS: 1. A pet food product comprising: a) one or more compounds that bind to a GPRC6A receptor or a functional fragment thereof; or b) a flavor composition comprising one or more compounds that bind to a GPRC6A receptor or a functional fragment thereof. 2. The pet food product of claim 1, wherein the pet food product has enhanced palatability. 3. The pet food product of claim 1 or 2, wherein the one or more compound increases, decreases or modulates the biological activity of the GPRC6A receptor. 4. The pet food product of any one of claims 1-3, wherein the one or more compound is selected from the group consisting of amino acids, peptides, hormones, ions, metals, butanoic acid-based compounds, propanoic acid-based compounds, pentanoic acid-based compounds, carboxylic acid-based compounds, derivatives thereof, and combinations thereof. 5. The pet food product of any one of claims 1-4, wherein the one or more compound has an EC50 value of no more than about 50 mM in connection with a biological activity of the GPRC6A receptor. 6. The pet food product of any one of claims 1-5, wherein the compound has the formula: . 7. The pet food product of claim 6, wherein R1 is selected from the group consisting of H, C₁-C₂₀ alkyl, branched C₁-C₂₀ alkyl, unbranched C₁-C₂₀ alkyl, C₁-C₂₀ alkenyl, brached C₁- C₂₀ alkenyl, unbranched C₁-C₂₀ alkenyl, C₁-C₂₀ alkynyl, branched C₁-C₂₀ alkynyl, unbranched C1-C20 alkynyl, arylalkyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, heteroarylalkyl, haloalkyl, CF3, halogen, phenyl, -C(O)R3, -COOR3, -NR3R4, -NO2, -OH, -OR₃, -CONR₃R₄, -S-Aryl, -O-Aryl, -N-Aryl, -NO₂, -SO₃H, -SO₂R₃, -NHOH, -C=CR₃, - C=NOH, -OP(O)(OH)2, and CHO. 8. The pet food product of claim 7, wherein R3 and R4 are each independently selected from the group consisting of H, C₁-C₂₀ alkyl, branched C₁-C₂₀ alkyl, unbranched C₁-C₂₀ alkyl, C₁-C₂₀ alkenyl, brached C₁-C₂₀ alkenyl, unbranched C₁-C₂₀ alkenyl, C₁-C₂₀ alkynyl, branched C1-C20 alkynyl, unbranched C1-C20 alkynyl, arylalkyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, heteroarylalkyl, haloalkyl, CF₃, and halogen. 9. The pet food product of any one of claims 6-8, wherein R₁ is substituted. Active 118427983.2 51

069269.0689 PATENT 10. The pet food product of any one of claims 6-9, wherein R2 is selected from the group consisting of H, C₁-C₂₀ alkyl, branched C₁-C₂₀ alkyl, unbranched C₁-C₂₀ alkyl, C₁-C₂₀ alkenyl, brached C₁-C₂₀ alkenyl, unbranched C₁-C₂₀ alkenyl, C₁-C₂₀ alkynyl, branched C₁- C20 alkynyl, unbranched C1-C20 alkynyl, arylalkyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, and heteroarylalkyl. 11. The pet food product of any one of claims 6-10, wherein R₂ is H or methyl. 12. The pet food product of any one of claims 1-5, wherein the compound has the formula: . 13. The pet food of claim 12, wherein R is selected from the group consisting of H, C₁-C₂₀ alkyl, branched C1-C20 alkyl, unbranched C1-C20 alkyl, C1-C20 alkenyl, brached C1-C20 alkenyl, unbranched C₁-C₂₀ alkenyl, C₁-C₂₀ alkynyl, branched C₁-C₂₀ alkynyl, unbranched C₁-C₂₀ alkynyl, arylalkyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, heteroarylalkyl, haloalkyl, CF3, halogen, phenyl, -C(O)R3, -COOR3, -NR3R4, -NO2, -OH, -OR3, - CONR3R4, -S-Aryl, -O-Aryl, -N-Aryl, -NO2, -SO3H, -SO2R3, -NHOH, -C=CR3, -C=NOH, -OP(O)(OH)₂, and CHO. 14. The pet food product of claim 13, wherein R₁ and R₂ are each independently selected from the group consisting of H, C1-C20 alkyl, branched C1-C20 alkyl, unbranched C1-C20 alkyl, C₁-C₂₀ alkenyl, brached C₁-C₂₀ alkenyl, unbranched C₁-C₂₀ alkenyl, C₁-C₂₀ alkynyl, branched C₁-C₂₀ alkynyl, unbranched C₁-C₂₀ alkynyl, arylalkyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, heteroarylalkyl, haloalkyl, CF3, and halogen. 15. The pet food product of any one of claims 12-14, wherein R is substituted. 16. The pet food product of any one of claims 6-15, wherein the compound comprises: a) includes an L-amino-acid; b) includes one carbon after the ^^-carbon of the amino-acid unit; c) can include a positively-charged group at a distance up to ~9A from the ^^-carbon (alpha carbon denoting the carbon of the compound to the amino group to the carboxyl group); and/or d) does not include a negatively-charged group at a distance up to ~9A from ^^-carbon. 17. The pet food product of any one of claims 1-16, wherein the one or more compound is present at a concentration of between about 0.0001% and about 2% weight/weight (w/w) in the pet food product. Active 118427983.2 52

069269.0689 PATENT 18. The pet food product of any one of claims 1-16, wherein the flavor composition is present at a concentration of between about 0.0001% and about 2% weight/weight (w/w) in the pet food product. 19. The pet food product of any one of claims 1-16, wherein the one or more compound is present at a concentration of between about 0.00001% and about 5% in the flavor composition. 20. The pet food product of any one of claims 1-19, wherein the GPRC6A receptor is a feline GPRC6A receptor. 21. The pet food product of any one of claims 1-19, wherein the GPRC6A receptor is a canine GPRC6A receptor. 22. A method for increasing palatability of a pet food product, the method comprising providing a pet food product; and a) admixing the pet food product with at least one compound that binds to one or more amino acids of a GPRC6A receptor; or b) admixing the pet food product with at least one flavor composition, wherein the flavor composition comprises a compound that binds to one or more amino acids of a GPRC6A receptor. 23. The method of claim 22, wherein the at least one compound is selected from the group consisting of amino acids, peptides, hormones, ions, metals, butanoic acid-based compounds, propanoic acid-based compounds, pentanoic acid-based compounds, carboxylic acid-based compounds, derivates thereof, and combinations thereof. 24. The method of claim 22 or 23, wherein the compound has the formula: . 25. The method of claim 24, wherein R₁ is selected from the group consisting of H, C₁-C₂₀ alkyl, branched C₁-C₂₀ alkyl, unbranched C₁-C₂₀ alkyl, C₁-C₂₀ alkenyl, brached C₁-C₂₀ alkenyl, unbranched C1-C20 alkenyl, C1-C20 alkynyl, branched C1-C20 alkynyl, unbranched C1-C20 alkynyl, arylalkyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, heteroarylalkyl, haloalkyl, CF₃, halogen, phenyl, -C(O)R₃, -COOR₃, -NR₃R₄, -NO₂, -OH, -OR₃, - CONR3R4, -S-Aryl, -O-Aryl, -N-Aryl, -NO2, -SO3H, -SO2R3, -NHOH, -C=CR3, -C=NOH, -OP(O)(OH)2, and CHO. 26. The method of claim 25, wherein R₃ and R₄ are each independently selected from the group consisting of H, C1-C20 alkyl, branched C1-C20 alkyl, unbranched C1-C20 alkyl, C1-C20 Active 118427983.2 53

069269.0689 PATENT alkenyl, brached C1-C20 alkenyl, unbranched C1-C20 alkenyl, C1-C20 alkynyl, branched C1- C₂₀ alkynyl, unbranched C₁-C₂₀ alkynyl, arylalkyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, heteroarylalkyl, haloalkyl, CF₃, and halogen. 27. The method of any one of claims 24-26, wherein R1 is substituted. 28. The method of any one of claims 24-27, wherein R2 is selected from the group consisting of H, C₁-C₂₀ alkyl, branched C₁-C₂₀ alkyl, unbranched C₁-C₂₀ alkyl, C₁-C₂₀ alkenyl, brached C1-C20 alkenyl, unbranched C1-C20 alkenyl, C1-C20 alkynyl, branched C1-C20 alkynyl, unbranched C1-C20 alkynyl, arylalkyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, and heteroarylalkyl. 29. The method of any one of claims 24-28, wherein R2 is H or methyl. 30. The method of claim 22 or 23, wherein the compound has the formula: . 31. The method of claim 30, wherein R is selected from the group consisting of H, C1-C20 alkyl, branched C1-C20 alkyl, unbranched C1-C20 alkyl, C1-C20 alkenyl, brached C1-C20 alkenyl, unbranched C₁-C₂₀ alkenyl, C₁-C₂₀ alkynyl, branched C₁-C₂₀ alkynyl, unbranched C₁-C₂₀ alkynyl, arylalkyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, heteroarylalkyl, haloalkyl, CF3, halogen, phenyl, -C(O)R3, -COOR3, -NR3R4, -NO2, -OH, -OR3, - CONR₃R₄, -S-Aryl, -O-Aryl, -N-Aryl, -NO₂, -SO₃H, -SO₂R₃, -NHOH, -C=CR₃, -C=NOH, -OP(O)(OH)₂, and CHO. 32. The method of claim 31, wherein R1 and R2 are each independently selected from the group consisting of H, C₁-C₂₀ alkyl, branched C₁-C₂₀ alkyl, unbranched C₁-C₂₀ alkyl, C₁-C₂₀ alkenyl, brached C₁-C₂₀ alkenyl, unbranched C₁-C₂₀ alkenyl, C₁-C₂₀ alkynyl, branched C₁- C20 alkynyl, unbranched C1-C20 alkynyl, arylalkyl, aryl, cycloalkyl, heterocyclyl, heteroaryl, heteroarylalkyl, haloalkyl, CF3, and halogen. 33. The method of any one of claims 30-32, wherein R is substituted. 34. The method of any one of claims 24-33, wherein the compound comprises: a) includes an L-amino-acid; b) includes one carbon after the ^^-carbon of the amino-acid unit; c) can include a positively-charged group at a distance up to ~9A from the ^^-carbon (alpha carbon denoting the carbon of the compound to the amino group to the carboxyl group); and/or d) does not include a negatively-charged group at a distance up to ~9A from ^^-carbon. Active 118427983.2 54

069269.0689 PATENT 35. The method of any one of claims 22-34, wherein the at least one compound binds to one or more amino acids of a Venus Flytrap Domain of the GPRC6A receptor. 36. The method of any one of claims 22-35, wherein the least one compound binds to one or more amino acids of a 7-transmembrane domain of the GPRC6A receptor. 37. The method of any one of claims 22-36, wherein the GPRC6A receptor is a feline GPRC6A. 38. The method of claim 37, wherein the at least one compound binds to one or more amino acids of the feline GPRC6A receptor selected from the group consisting of Tyr148, Ser149, Glu170, Thr172, Asp 218, Tyr220, Arg279, Asp303, Asn304, Thr307, Arg399, Asn400, and combination thereof. 39. The method of claim 37 or 38, wherein the compound binds to one or more amino acids of the feline GPRC6A receptor selected from the group consisting of Arg662, Gln663, Phe666, Gly667, Phe670, Gln715, Glu746, Ala751, Phe752, Met755, Leu756, Ile759, Tyr793, Trp797, Phe800, Tyr804, Glu816, Val819, Ile820, and combinations thereof. 40. The method of any one of claims 22-36, wherein the GPRC6A receptor is a canine GPRC6A. 41. The method of claim 40, wherein the at least one compound binds to one or more amino acids of the canine GPRC6A receptor selected from the group consisting of Tyr148, Ser149, Glu170, Thr172, Asp 218, Tyr220, Arg279, Asp303, Asn304, Met307, Arg399, Asn400, and combination thereof. 42. The method of claim 40 or 41, wherein the compound binds to one or more amino acids of the GPRC6A receptor selected from the group consisting of Arg662, Gln663, Phe666, Gly667, Phe670, Gln715, Glu746, Ala751, Phe752, Met755, Leu756, Ile759, Tyr793, Trp797, Phe800, Tyr804, Glu816, Val819, Ile820, and combinations thereof. 43. The method of any one of claims 22-42, wherein the at least one compound is present at a concentration of between about 0.0001% and about 2% in the pet food product. 44. The method of any one of claims 22-42, wherein the flavor composition is present at a concentration of between about 0.001% and about 2% in the pet food product. 45. The method of any one of claims 22-42, wherein the at least one compound is present at a concentration of between about 0.00001% and about 5% in the flavor composition. 46. The method of any one of claims 22-45, wherein the method comprises thermal processing of a food product precursor, wherein the compound is generated during the thermal processing. Active 118427983.2 55