FR3014886A1 - PROCESS FOR EXTRACTING PURINE - Google Patents

Abstract

The present invention relates to a method for extracting a purine by a surfactant, the purine extract obtained and the use of said extract.

Description

FIELD OF THE INVENTION The present invention relates to the extraction of purines. More specifically, the present invention relates to a method of extracting guanine by a surfactant. Advantageously, the guanine extracted according to the invention comes from a natural material rich in guanine, such as in particular fish scales. Many taxonomic groups, such as fish or spiders, use guanine crystals to generate structural colors. A structural color interacts with the light to give iridescence or glare; its appearance therefore depends on the incidence of light. The presence of guanine at the level of the skin covering their scales thus gives the so-called silver fish (herring, sardines, etc.) a metallic appearance. Because of these particular coloring properties, guanine crystals extracted from fish scales have been used in various fields. Thus, guanine crystals are used in jewelery to cover resin or glass beads to give them the pearly and iridescent appearance of natural pearls. Because of this use, guanine crystal emulsions are available under the generic name of "pearl essence" or essence of orient. Guanine crystals can also be used in the cosmetic industry in the formulation of care products or shampoos, to give them an iridescent and pearlescent white color. Methods for extracting guanine crystals from biological samples, such as fish scales, have been known for a long time.

GB 188,774 (1921) discloses a process for producing guanine crystals, wherein the raw material comprising guanine crystals (eg fish scales) is treated with animal enzymes and / or various detergent substances, for example example of saponin. This process comprises non-selective sedimentation, which leads to the co-purification of undesirable molecules. French patent FR 600,481 (1924) describes a process for purifying guanine crystals, comprising the use of a varnish whose solvent is not miscible with water, for example tetrachloroethane. This process makes it possible to obtain an emulsion of 10 crystals. US Patent 308,362 (1929) discloses a method of extracting guanine crystals from herring scales, including the use of hydrochloric acid and pepsin. US Patent 645,803 (1948) discloses a process for preparing guanine crystals, said process using water immiscible liquids such as esters, ethers or chloroform. US Patent 2005/142083 discloses a method of extracting guanine crystals from fish scales, said method comprising washing with water with stirring, concentration by sedimentation or centrifugation, and mixing with an agent. organic, for example aromatic esters, preferably in the presence of a surfactant. This method has the disadvantage of using solvents and oils difficult to remove, and NaBH4, which is a toxic and flammable product. The processes of the prior art have the disadvantage of being slow to implement and use polluting and toxic products, for example organic solvents. Moreover, the by-products of these processes are generally polluting, and expensive to eliminate. There is therefore a risk of contamination of the environment, and toxicity to the consumer, especially when guanine crystals are incorporated into cosmetics.

The present invention therefore relates to a process for extracting guanine which does not have the disadvantages of the processes of the prior art. Thus, the inventors have developed an extraction process in which no polluting or toxic product (such as, for example, an organic solvent) is used, in order to limit the risks of contamination of the environment, and to increase consumer safety. SUMMARY The present invention thus relates to a process for extracting a purine by at least one surfactant, preferably an anionic surfactant, a zwitterionic surfactant and / or a nonionic surfactant. According to one embodiment, said purine is guanine, hypoxanthine or a mixture of guanine and hypoxanthine. According to another embodiment, said purine is in crystalline form. According to one embodiment, the purine is extracted from a material of animal origin, preferably fish scales. According to one embodiment, the surfactant is an anionic surfactant, preferably selected from sarkosyl, and disodium cocoyl glutamate and dipalmitoylethyl hydroxyethylmonium methosulfate. According to another embodiment of the invention, the surfactant is an amino acid derivative, preferably the surfactant is sarkosyl. According to one embodiment, the method further comprises a bleaching step with a bleaching agent, preferably hydrogen peroxide. According to another embodiment, the method of the invention further comprises a step of enzymatic digestion, preferably with a catalase. According to another embodiment, the method of the invention further comprises a crystallization step, preferably in a solvent, more preferably in water. The present invention also relates to a purine extract obtained by the process as described above.

The present invention further relates to the use of a purine extract according to the invention as a coloring agent. The present invention also relates to a composition comprising the purine extract according to the invention.

The present invention also relates to a purine extract at least 20% pure, characterized in that it is not synthesized chemically or obtained chemically. According to one embodiment of the invention, the purine extract has an ash content of less than 20%; and / or less than 2% of amino acids by mass relative to the total mass of the extract. According to another embodiment of the invention, the purine extract is characterized in that its color measured according to the CIE Lab model (also called L * a * b) has an L (clarity) component greater than or equal to 85 , preferably greater than or equal to 88, and more preferably greater than or equal to 90. According to a particular embodiment, the purine extract may also be characterized in that its color measured according to the CIE Lab model (also called L * a * b) has the following characteristics: a component a (range of the red-green axis) ranging from -1 to 1; and / or a component b (range of the yellow-blue axis) varying from 0 to 15. According to another embodiment of the invention, the extract has a residual hydrogen peroxide content of less than 50 mg / ml. L.

DEFINITIONS In the present invention, the following terms have the following meaning: "Purine": Purine is a heterocyclic nitrogenous molecule consisting of a pyrimidine ring fused to an imidazole ring. There are 6 usual isomers of purine constitution: 9H-purine, 7H-purine, 6H-purine, 3H-purine, 2H-purine and 1H-purine. The structure of 9H-purine is represented below: ## STR2 ## For the purposes of the present invention, the term "purine" also refers to the derivatives of purine, among which can be mentioned adenine, guanine , xanthine, hypoxanthine, theobromine, caffeine, uric acid and mixtures thereof. "Guanine", or 2-amino-1,9-dihydro-6H-purin-6-one: purine nitrogen base of general formula C5H5N50, existing in 6 tautomeric forms including 4 stereoisomers (1.9H, 1.7H , 3.9H and 3.7H) and 2 tautomers with a different functional group (7,11H and 9,11H: oxo-hydroxy). The formula of 1,9H-guanine is shown below: HN 1 ............ N 0 6 N 3 H2N 2 Guanine is a white dye accepted in cosmetics. "Hypoxanthine" or 6-oxypurine: purine nitrogen base of general formula C5H4N40 having the following structural formula: - "Amino acids": class of chemical compounds having a carboxyl group and an amine group, in which the amine group is bound to the carbon atom adjacent to the carboxylic acid group (peptide bond). The amino acids thus have the general formula H2N-CHR-COOH, where R represents the side chain which identifies the amino acid. An amino acid derivative refers to a chemical compound obtainable from an amino acid, for example by enzymatic reaction. An amino acid derivative comprises a peptide bond. Preferably, the amino acid derivative according to the invention comprises a lipophilic, typically N-terminal, preferably C6-24 alkyl, carboxylic acid or ester end. Preferably, the amino acid derivative according to the invention comprises a hydrophilic end, typically C-terminal, preferably carboxylic acid or ester. "Alkyl" means a linear or branched hydrocarbon chain, saturated or unsaturated, of 6 to 24 carbon atoms. The term "carboxylic acid" (-C (O) OH) denotes a molecule comprising one or more carboxyl group (s). The "ester" function denotes a group of atoms formed of an atom simultaneously bonded to an oxygen atom by a double bond and to an alkoxy group of the -O-R 'type. By "alkoxy" is meant any O-alkyl or O-aryl group. The term "aryl" means a mono- or polycyclic system of 5 to 20 carbon atoms having one or more aromatic rings, among which mention may be made of the phenyl group, the biphenyl group, the 1-naphthyl group and the 2-naphthyl group. , the tetrahydronaphthyl group, the indanyl group, and the binaphthyl group. The term aryl also means any aromatic ring comprising at least one heteroatom selected from oxygen, nitrogen or sulfur. "Surfactant" or "Surfactant": amphiphilic compound that modifies the surface tension between two surfaces. According to one embodiment of the invention, the surfactant is an "ionic surfactant", ie a surfactant that has a net charge at pH 7, which can be either positive ("cationic surfactant") or negative ("anionic surfactant"). ). Conversely, according to another embodiment, the surfactant is a "nonionic surfactant", which is not loaded at pH 7. "Amphiphilic compound": compound which has a lipophilic part, and a hydrophilic part. "About", in front of a number, means plus or minus 10% of the nominal value of that number. "Biodegradable": refers to a substance that can, under the action of living organisms, break down into various elements devoid of harmful effect on the natural environment (JORF definition No. 0087 of 12 April 2009 page 6438) . DETAILED DESCRIPTION The present invention relates to a process for extracting a purine by a surfactant, preferably a water-insoluble purine. More particularly, said extraction process does not use liquids or organic solvents. Examples of organic solvents are hydrocarbon solvents such as alkanes, alkenes, benzene, toluene, xylene; oxygenated solvents such as alcohols, ketones, acids, esters, ethers, DMF, DMSO and HMPT; and halogenated solvents such as halogenated hydrocarbons (fluorinated, chlorinated, brominated or iodinated): perchlorethylene, trichlorethylene, dichloromethane, chloroform, tetrachloromethane ... According to one embodiment of the invention, the purine is selected from the list comprising the guanine, adenine, xanthine, hypoxanthine, theobromine, caffeine, uric acid and mixtures thereof. Advantageously, the purine is guanine, hypoxanthine or a mixture of guanine and hypoxanthine. According to one embodiment of the invention, the purine is in crystalline form. Accordingly, according to this embodiment, the method of the invention is a method for extracting purine crystals. According to one embodiment of the invention, said purine crystal comprises guanine and hypoxanthine. According to one embodiment, the guanine: hypoxanthine ratio in the crystal varies from 50:50 to 99.9: 0.1, preferably ranges from 60:40 to 99: 1, even more preferably from 75:25 to 97: 3.

Such crystals comprising guanine and hypoxanthine may be of animal origin, and may in particular be synthesized by certain fish. The relative percentages of guanine and hypoxanthine vary according to the animal species considered. According to one embodiment of the invention, the process according to the invention relates to the extraction of purine from a material comprising a purine, preferably of a natural material, more preferably of animal origin. Examples of natural materials of animal origin comprising a purine, preferably guanine / hypoxanthine crystals include, but are not limited to, dark fish scales, such as, for example, herring, salmon, sardines, koi carp, etc ...; swimbladders (also known as gaseous bladders) of some fish; bird droppings; some insects; some spiders, such as, for example, Tetragnatha montana, Latrodectus pallidus and Argiope lobata. Advantageously, the natural material of animal origin comprising guanine / hypoxanthine crystals is formed of fish scales, preferably herring scales. According to one embodiment of the invention, the material comprising a purine may have been frozen before being subjected to the process according to the invention. According to one embodiment of the invention, the material comprising a purine can be homogenized or lysed before being subjected to the process according to the invention. Methods of homogenizing or lysing a substrate prior to extraction are well known to those skilled in the art. Examples of such methods include, but are not limited to, methods for lysing cells or tissues for the subsequent extraction of proteins and / or nucleic acids, such as, for example, lysing cells with a buffer containing SDS or proteinase K, cell lysis by sonication, lysis of cells by the use of a polytron and / or detergent (s). According to one embodiment of the invention, when the object of the process of the invention is to extract a purine that is soluble in water, the process also comprises a step of precipitating said purine. Water soluble purine precipitation techniques are specific for each purine, and are well known to those skilled in the art. According to another embodiment, when the method of the invention has the object of extracting a water-soluble purine, said method may comprise an ultracentrifugation step, the parameters of which can be determined easily by the man of the invention. job. According to one embodiment of the invention, the surfactant according to the invention is an anionic surfactant. Examples of anionic surfactants which can be used in the process of the invention include, but are not limited to, sarkosyl (Sodium lauroyl sarcosinate), disodium cocoyl glutamate, dipalmitoylethyl hydroxyethylmonium methosulfate, sodium dodecyl sulfate (SDS), 3, 7, 12-Trihydroxy-5 (3-cholan-24-oic acid, monosodium salt (or sodium cholate), and (3a, 5 (3, 12a, 20R) -3,12-dihydroxycholan-24- oic acid, monosodium salt (or sodium deoxycholate) and mixtures thereof.

According to another embodiment of the invention, the surfactant is a zwitterionic surfactant. Examples of zwitterionic surfactants that may be used in the process of the invention include, but are not limited to, N-decyl-N, N-dimethyl-3-ammonio-1-propanesulfonate (or SB 3-10 or decyl- sulfobetaine), N-Dodecyl-N, N-dimethyl-3-aminio-1-propanesulfonate (or SB 3-12 or dodecyl-sulfobetaine), N-Tetradecyl-N, N-dimethyl-3-ammonio-1 propanesulfonate (or SB 3-14) and 3- [(3-cholamidopropyl) dimethylammonio (-1-propanesulfonate (or CHAPS) and mixtures thereof. According to another embodiment of the invention, the surfactant is a non-surfactant. Examples of nonionic surfactants which can be used in the process of the invention include, but are not limited to, dodecyl octaethylene glycol (C12E8), nonanoyl methylglucamine (MEGA 9), octylglucoside, dodecyl dimethylamine oxide (LDAO), Triton X-100, Triton X-114, Tween-20, Tween-60, Tween80 and mixtures thereof. the invention, the surfactant is an amphiphilic derivative of an amino acid, preferably an amphiphilic derivative of glycine or glutamic acid. Examples of surfactants that are amphiphilic derivatives of an amino acid include, but are not limited to, sarkosyl and disodium cocoyl glutamate and mixtures thereof. According to one embodiment of the invention, a mixture of surfactants is used. Preferably, the surfactant is sarkosyl, disodium cocoyl glutamate or dipalmitoylethyl hydroxyethylmonium methosulfate, more preferably the surfactant is sarkosyl. According to one embodiment of the invention, the surfactant is in solution, preferably is in aqueous solution. According to one embodiment of the invention, the concentration of surfactant in the solution varies from 0.01 to 10% by weight relative to the total volume of the solution, preferably from 0.1 to 5% w / v, more preferably from about 1% w / v. According to the process of the invention, the extraction of the purine is carried out by mixing the material comprising the purine with a surfactant. According to one embodiment of the invention, the material comprising the purine and the surfactant, preferably the surfactant solution, are mixed in a ratio of material: surfactant ranging from 1: 1 to 1:10, preferably from 1: 2 to 1: 5, still more preferably about 1: 2.66. According to one embodiment of the invention, the extraction is carried out with stirring, preferably from 100 to 1500 rpm, more preferably from 500 to 1000 rpm, still more preferably at about 700 rpm. According to one embodiment of the invention, the extraction is carried out at ambient temperature, preferably between 15 and 25 ° C.

According to one embodiment of the invention, the material comprising a purine and the surfactant are left in contact for a period ranging from 1 minute to 2 hours, preferably from 10 minutes to 1 hour, more preferably for about 30 minutes.

The present invention also relates to a purine extract in a surfactant, obtained according to the method described above. The present invention also relates to a solids solids extract obtained from the purine extract in a solvent of the invention. According to one embodiment, the solids solids extract is obtained by centrifuging the purine extract in a solvent, optionally followed by drying the centrifugation pellet. According to one embodiment of the invention, the purine solids content has a percentage of humidity less than or equal to 70% by weight of water relative to the total mass of the extract, preferably less than or equal to 50% w / w, more preferably less than or equal to 40%, 20%, 10%, 5%, and even more preferably less than or equal to 2% w / w. According to a first embodiment of the invention, the solids solids content has a percentage of humidity ranging from 20 to 70%, preferably from 30 to 60%, even more preferably from 40 to 50% by weight. relative to the total mass of the dry extract. According to a second embodiment of the invention, the purine solids content has a percentage of moisture of less than or equal to 10%, preferably less than or equal to 5%, preferably less than or equal to 2%, mass relative to the total mass of the dry extract. Accordingly, according to one embodiment of the invention, the method according to the invention further comprises a step of centrifuging the purine extract in a surfactant according to the invention. According to one embodiment, the centrifugation speed ranges from 3,000 to 10,000 rpm, preferably from 4,500 to 7,500 rpm, more preferably the centrifugation speed is about 6,000 rpm. In one embodiment, the centrifugation rate ranges from about 5,000 to about 20,000 grams, preferably from about 8,000 to about 13,000 grams, more preferably about 11,000 grams. According to one embodiment of the invention, the centrifugation rate varies from 1 to 1000 ml / minute, preferably from 20 to 500 ml / minute, more preferably the centrifugation rate is about 120 ml / minute. According to one embodiment of the invention, the centrifugation rate varies from 1 to 1000 L / hour, preferably from 50 to 250 L / hour, more preferably still the centrifugation rate is about 100 L / hour.

According to one embodiment of the invention, the centrifugation is carried out at a temperature ranging from more than 0 ° C to 25 ° C, preferably from 2 ° C to 10 ° C, even more preferably about 4 ° C. According to one embodiment of the invention, the centrifugation is carried out in one step. According to another embodiment, the centrifugation is carried out in more than one step, for example in two steps. According to one embodiment of the invention, the dry extract of purine corresponds to the pellet of centrifugation. According to one embodiment of the invention, the centrifugation pellet has a percentage of humidity ranging from 20 to 70%, preferably from 30 to 60%, still more preferably from 40 to 50%, by weight of water per relative to the total mass of the pellet. According to one embodiment of the invention, the centrifugation pellet is dried, for example by drying in an oven, at a temperature ranging from 20 to 70 ° C., preferably from 30 to 60 ° C., more preferably from 45 to 60 ° C. at 50 ° C for a period of 1 to 3 days, preferably 12 to 48 hours, more preferably 16 to 24 hours. According to one embodiment of the invention, the dry extract of purine corresponds to the dried extract in an oven. According to one embodiment of the invention, the oven dried extract has a percentage of moisture of less than or equal to 10%, preferably less than or equal to 5%, preferably less than or equal to 2%, in mass of water relative to the total mass of the dried oven extract. According to one embodiment of the invention, the process of the invention comprises, prior to extraction, a washing step of the starting material comprising a purine. According to one embodiment of the invention, the material comprising a purine is washed with water, preferably with cold water. Advantageously, from 1 to 10 volumes, preferably from 2 to 5 volumes, more preferably from 3 to 4 volumes of water are used per volume of material. According to one embodiment of the invention, said washing step is carried out on a sieve, in order to eliminate the maximum of elements contaminating the material comprising a purine. The size of the sieves to be used depends on the nature of the material comprising a purine, and can be easily estimated by those skilled in the art. According to one embodiment of the invention, the material comprising purine is formed of fish scales, preferably herring scales, and the screen has a mesh of 1 to 10 mm, preferably 2 to 5 mm, even more preferably about 3 mm, to eliminate, for example, the remains of fish or algae contaminating the material. According to one embodiment of the invention, the method of the invention comprises, after the extraction step, one or more steps of sieving the purine extract in a surfactant. These optional steps make it possible to retain the solid impurities of the extract, such as the remains of material from which the purine has been extracted (hereinafter referred to as "treated material"), while the purine extract is recovered in the sieve. The size of the sieves to be used depends on the nature of the material comprising purine, and can be easily estimated by those skilled in the art.

According to one embodiment of the invention, the material comprising purine is formed of fish scales, preferably herring scales, and the sieve has a mesh of 1 to 10 mm, preferably 2 to 5 mm, even more preferably about 3 mm, in order to retain the scales from which the purine has been extracted (constituting the treated material). According to one embodiment of the invention, the treated material is washed after sieving, in order to recover the maximum of purine. According to one embodiment, the washing is carried out with water on the sieve, preferably in a volume ranging from 0.1 to 10 volumes per 1 volume of material treated, preferably from 0.5 to 5 volumes, more preferably from about 1 to volume for 1 volume of treated material. According to one embodiment of the invention, the sieve is again filtered on a finer mesh filter. According to one embodiment of the invention, the material comprising purine is formed of fish scales, preferably scales of herring, and the sieve used in the second sieving step has a mesh of 10 μm to 1 μm. mm, preferably from 50 pm to 500 pm, still more preferably from about 100 pm, in particular to retain the large particles present in the extract, such as, for example, melanin particles present in the extract. The subject of the invention is also the treated material of the process according to the invention.

According to one embodiment of the invention, the method of the invention further comprises a step of bleaching purine extracted according to the method of the invention. Advantageously, the bleaching step is carried out before the step of drying the pellet resulting from the centrifugation of the extract of purine in a solvent. According to one embodiment of the invention, the bleaching step comprises resuspending the pellet or dry extract of purine according to the invention, in a whitening agent, and incubating the suspension, preferably under agitation (for example thanks to a magnetic bar).

Examples of bleaching agents that may be used include, but are not limited to, hydrogen peroxide, potassium permanganate, benzoyl peroxide, oxalic acid, ultraviolet rays, potassium permanganate blends, and the like. oxalic acid and hydrogen peroxide associated with ultraviolet treatment. According to one embodiment of the invention, the whitening agent is a solution of hydrogen peroxide whose concentration varies from 0.1 to 10% by volume of hydrogen peroxide relative to the total volume of the solution, preferably from 1 to 5% v / v, more preferably about 2% by volume of hydrogen peroxide with respect to the total volume of the solution. According to one embodiment of the invention, the whitening agent is a hydrogen peroxide solution whose concentration varies from 0.1 to 10% by weight of hydrogen peroxide relative to the total volume of the solution, preferably from 1 to 5% w / v, more preferably about 1.5% w / v. According to one embodiment of the invention, the incubation time varies from 1 to 48 hours, preferably from 2 to 24 hours, more preferably from 12 to 20 hours, and even more preferably is approximately 16 hours. According to one embodiment of the invention, the incubation is carried out at room temperature, preferably between 15 and 25 ° C. According to one embodiment of the invention, the purine bleaching step is followed by successive steps of washing and centrifugation to reduce the amount of bleaching agent in the extract at a concentration of less than 50 mg. / L, preferably less than 20 mg / L, more preferably less than 10 mg / L. According to one embodiment of the invention, the washes are carried out with water, and followed by centrifugation. According to one embodiment, the centrifugation speed varies from 3000 to 10,000 rpm, preferably from 4500 to 8000 rpm, more preferably the centrifugation speed is about 7000 rpm.

According to one embodiment of the invention, the centrifugation rate varies from 1 to 1000 ml / minute, preferably from 20 to 500 ml / minute, more preferably still the centrifugation rate is about 210 ml / minute. According to one embodiment of the invention, the centrifugation is carried out at a temperature ranging from more than 0 ° C. to 25 ° C., preferably from 2 ° C. to 10 ° C., even more preferentially by about 4 ° C. . According to one embodiment of the invention, the washing and centrifugation steps are repeated until the desired concentration of whitening agent in the extract is reached. Advantageously, the desired concentration is a concentration of less than 50 mg / l, preferably less than 20 mg / l, more preferably less than 10 mg / l. According to one embodiment of the invention, the centrifugation pellet is dried, for example by drying in an oven, at a temperature ranging from 20 to 70 ° C., preferably from 30 to 60 ° C., more preferably from 45 to 60 ° C. at 50 ° C for a period of 1 to 3 days, preferably 12 to 48 hours, more preferably 16 to 24 hours. According to one embodiment of the invention, the centrifugation pellet is dried by lyophilization. Another subject of the invention is a whitened dry extract of purine, obtained according to the method described above. According to one embodiment of the invention, the process of the invention further comprises a step of crystallizing the purine extracted according to the method of the invention. Advantageously, the crystallization step is carried out after the bleaching step as described above. According to one embodiment of the invention, the crystallization is carried out at a temperature of about 60 to 140 ° C, preferably about 90 to 110 ° C, more preferably about 100 ° C.

According to one embodiment of the invention, the crystallization is carried out in a solvent, preferably in water. According to one embodiment of the invention, the solvent, preferably water, is added in a ratio of guanine extract: solvent of from 1: 0.1 to 1: 10 approximately, preferably from 1: 0.5 to 1: 5 approximately more preferably from 1: 0.5 to 1: 3 approximately. According to one embodiment of the invention, the crystallization is carried out for 1 minute to about 5 hours, preferably for 10 minutes to 3 hours, more preferably for 30 minutes to 2 hours. According to one embodiment of the invention, the crystallization step leads to the formation of a floating white foam ("foam") comprising guanine, which can be recovered, for example by filtration. According to one embodiment, the filtration is carried out in a filter of approximately 10 to 500 μm, preferably of approximately 50 to 250 μm, more preferably of approximately 100 μm. According to one embodiment of the invention, the filtration is a vacuum filtration at hot. According to one embodiment of the invention, the hot filtrate obtained after filtration under hot vacuum is recovered, it is then left to rest so that it cools slowly, and the guanine which had solubilized during the step of the crystallization precipitates and can be recovered, for example by vacuum filtration under cold conditions. Advantageously, the percentage of guanine recovered varies from 0.25 to 2% relative to the weight of guanine initially used for the crystallization step. According to one embodiment, the guanine recovered after the filtration is recrystallized again in a solvent, preferably in water. According to one embodiment of the invention, the solvent, preferably water, is added in a ratio of guanine extract: solvent of about 1: 0.1 to 1: 10, preferably of 1: 0.5 to 1: 5. approximately, even more preferably from 1: 0.5 to 1: 3 approximately.

According to one embodiment of the invention, the recrystallization is carried out at a temperature of about 60 to 140 ° C., preferably of about 90 to 110 ° C., more preferentially of about 100 ° C. According to one embodiment of the invention, the recrystallization is carried out for 1 minute to 5 hours, preferably for 10 minutes to 3 hours, more preferably for 30 minutes to 2 hours. According to one embodiment of the invention, the recrystallization step leads to the formation of a floating guanine foam, which can be recovered, for example by filtration, preferably by vacuum filtration under hot conditions. According to one embodiment, the filtration is carried out in a filter of about 10 to 500 μm, preferably about 50 to 250 μm, more preferably about 100 μm. According to one embodiment of the invention, the hot filtrate obtained after filtration under hot vacuum is recovered, it is then left to rest so that it cools slowly, and the guanine which had solubilized during the step of the Recrystallization precipitates and can be recovered, for example by vacuum filtration under cold conditions. According to one embodiment of the invention, another recrystallization step may be repeated if necessary depending on the degree of purity desired for guanine. According to one embodiment, the floating white foam comprising guanine is then dried. Preferably, the drying step is carried out at a temperature of approximately 20 to 100 ° C., more preferably of approximately 35 to 75 ° C., and even more preferentially of approximately 50 ° C., for approximately 5 to 72 hours, preferably for about 12 to 48 hours, more preferably for about 16 to 24 hours. According to one embodiment of the invention, the method according to the invention further comprises a step of enzymatic digestion of the material comprising purine. According to one embodiment, this enzymatic digestion step is carried out after the bleaching step, if the hydrogen peroxide is used.

According to one embodiment of the invention, the enzymatic digestion is carried out by an enzyme selected from catalases. Examples of catalases are monofunctional catalases, bifunctional catalase-peroxidases and manganese-containing catalases. Preferably, the catalase is of bacterial origin.

According to one embodiment of the invention, the enzymatic digestion is carried out at an enzyme concentration of 0.00001% to 5%, preferably 0.00005% to 3%, even more preferentially from 0.0001% to 2%, at a temperature of 0 to 100 ° C, preferably 2 to 80 ° C, more preferably 4 to 75 ° C, for a period of 1 min to 36 hours.

According to one embodiment of the invention, the extraction process of the invention makes it possible to obtain a purine extract in a solvent, and comprises or consists of the following steps: optionally washing the material comprising the purine; extraction of purine by a surfactant; optionally one or more crystallization steps; optionally one or more enzymatic digestion steps; and optionally one or more steps of sieving and washing the treated material. According to one embodiment of the invention, the extraction process of the invention makes it possible to obtain a solids solids extract, and comprises or consists of the following steps: optionally washing the material comprising the purine; - extraction of purine by a surfactant; optionally one or more steps of sieving and washing the treated material; one or more centrifugation steps of the extract of purine in a solvent; optionally one or more crystallization steps; optionally one or more enzymatic digestion steps; and optionally one or more steps of drying the centrifugation pellet.

According to one embodiment of the invention, the extraction process of the invention makes it possible to obtain a purified bleached extract of purine, and comprises or consists of the following steps: optionally washing the material comprising the purine; extraction of purine by a surfactant; optionally one or more steps of sieving and washing the treated material; centrifugation of the purine extract in a solvent; incubation of the centrifugation pellet in a whitening agent; optionally one or more crystallization steps; optionally one or more enzymatic digestion steps; washes and centrifugations of the purine extract; and drying. According to one embodiment of the invention, the method of the invention further comprises a step of reducing the residual odor of the purine extract. Advantageously, this step is carried out when the material from which guanine is extracted is of animal origin, preferably from fish. According to one embodiment of the invention, the reduction of the residual odor results from the treatment of the purine extract with a complex metal hydride, such as, for example, sodium borohydride. Such a residual odor reduction step of a purine extract is described in US2005 / 142083. Advantageously, to avoid any microbial contamination, for example any bacterial or fungal contamination, of the purine extract according to the invention, the material comprising the purine is kept cold until extraction. According to one embodiment of the invention, the material comprising the purine is stored at less than 4 ° C, preferably frozen. According to one embodiment of the invention, in order to avoid any microbial contamination of the purine extract, an additional step of microfiltration of the last sieve is carried out, preferably with a screen whose mesh size is less than 60. iam, more preferably less than 50 gm, even more preferably less than 40 pm. According to this embodiment, the method of the invention further comprises a microfiltration step as described above.

According to one embodiment of the invention, the extract according to the invention further comprises a preservative agent. Examples of preservatives include, but are not limited to, citric acid, benzoic acid or other natural preservatives disclosed by Tiwari et al (Application of Natural Antimicrobials for Food Preservation, J. Agric. Chem., 2009, 57 (14), pp 5987-6000). Tiwari et al. describe, for example, antimicrobial agents of plant, animal or microbial origin. Examples of plant-derived antimicrobial agents include, but are not limited to, essential oils of leaves (e.g. rosemary, sage, basil, oregano, thyme or marjoram), flowers or bud (e.g. cloves), bulbs (eg garlic or onions), seeds (eg caraway, fennel, nutgem or parsley), rhizomes (eg asafoetida) or fruits (eg pepper, pepper or cardamom), cinnamon or citral; compounds derived from plants, such as, for example, carvacrol, thymol, citral, eugenol and their precursors; isothiocyanates; vanillin; lemon extracts; cinnamamic aldehyde; terpenes such as, for example, phenolic monoterpenes, volatile terpenes; tea or garlic extracts. Examples of antimicrobial agents of animal origin include, but are not limited to, lysozyme; lactoperoxidase; antimicrobial peptides such as, for example, magainin, MSI-78, PR-39, spheniscol, pleurocidin, dermaseptin, K4S4, cecropin P1, melittin, LL-37, clavanin and the like. curvacine; defensins; lactoferrin; chitosan; lipids such as, for example, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Examples of antimicrobial agents of microbial origin include, but are not limited to, organic acids; hydrogen peroxide; diacetyl; bacteriocins such as, for example, nisin, diplococcin, acidophilin, bulgarican, helveticin, lactacin and plantaricin; reuterin; pediocin. According to one embodiment of the invention, the purine extract according to the invention is a dry extract of guanine / hypoxanthine crystals, and has at least one of the following characteristics: ash content of less than 20%, preferably less than 15%, more preferably less than or equal to 12% by weight relative to the total mass of the extract; and / or absence of amino acids, or presence of traces of amino acids. According to one embodiment of the invention, the presence of traces of amino acids corresponds to the presence of less than 2% of amino acids in mass relative to the total mass of the extract, preferably less than 1% w / w, more preferably less than 0.5% by weight relative to the total mass of the extract; and / or color (L component (clarity)) measured according to the CIE Lab model (also called L * a * b) greater than or equal to 85, preferably greater than or equal to 88, more preferably greater than or equal to 90; and / or residual hydrogen peroxide level of less than 50 mg / l, preferably less than 20 mg / l, more preferably less than 10 mg / l. According to a particular embodiment, the dry extract of guanine / hypoxanthine crystals may have, in addition to the value of the L component described above, the following characteristics: component a (range of the red-green axis) varying from -1 at 1, preferably from -0.75 to 0.75, more preferably from -0.5 to 0.5; and / or component b (range of the yellow-blue axis) ranging from 0 to 15, preferably from 2 to 12, even more preferably from 3.5 to 9.5. Methods for measuring the ash content of a product are known to those skilled in the art. A non-limiting example of such a method comprises drying in an oven at a temperature of more than 100 ° C, preferably of more than 500 ° C, still more preferably of approximately 650 ° C, for more than one hour, preferably more than 6 hours, more preferably during the night. Methods for evaluating the presence or absence of amino acids in a sample are known to those skilled in the art. An example of such a method includes, but is not limited to, gas chromatography, for example, using the EZ FAAST kit marketed by Phenomenex (Torrance, USA). Methods for evaluating the color of a product according to the CIE Lab model are well known to those skilled in the art. An example of such a method includes, but is not limited to, the use of a colorimeter, such as, for example, a MiniScan EZ portable colorimeter (HunterLab, VA, USA). According to one embodiment of the invention, the purine extract according to the invention is more than about 80% pure, preferably more than about 85%, more preferably more than about 88% pure. According to one embodiment of the invention, the purine extract according to the invention is not chemically synthesized. Methods for determining the purity of an extract are well known to those skilled in the art. Examples of methods for determining purity include, but are not limited to, determination of melting temperature, liquid chromatography (HPLC), UV-Vis molecular absorption spectrophotometry. According to one embodiment of the invention, the extract according to the invention is free from any microbial contamination. According to one embodiment of the invention, the microbial contamination of the extract according to the invention can be detected according to a method adapted from the method for counting total aerobic bacteria in food products and ingredients by means of enumeration plates. Aerobic PETRIFILM® 3M ™ (HPB Method, MFHPB-33 published February 2001, 25 of which is incorporated by reference). Other methods of detecting microbial contamination in a sample such as an extract are well known to those skilled in the art, and may be used within the scope of the present invention.

According to one embodiment of the invention, the bacterial contamination of the extract according to the invention is less than 100 CFU / mL (where CFU is the abbreviation of colonyforming unit), ie the number of viable microbial organisms is lower than at 100 per mL of product; preferably less than 50 CFU / mL, more preferably less than 10 CFU / mL. According to one embodiment of the invention, the extract according to the invention is biodegradable. According to one embodiment of the invention, all the by-products of the process of the invention are biodegradable. The by-products of the invention are, for example, the treated material, the surfactant and the hydrogen peroxide solutions. According to one embodiment of the invention, the by-products of the extraction process can be recycled. According to one embodiment of the invention, the treated material can be reused, for example in other extraction processes. According to one embodiment in which the material comprising purine is formed of fish scales, the method according to the invention further comprises a step of extracting the hydroxyapatite, collagen and / or gelatin from the fish. treated material. An example of a method for isolating collagen from fish scales is described in the article Pati et al (Bioresour Technol., 2010, 101 (10): 3737-42). The present invention also relates to the use of a purine extract according to the invention. According to one embodiment of the invention, the purine extract according to the invention is used as a dye. According to one embodiment of the invention, the purine extract is a dry extract of guanine / hypoxanthine crystals, and can be used as a white or pearlescent dye. Examples of the use of a dry extract of guanine / hypoxanthine crystals according to the invention include, but are not limited to, the use as a colorant in paints, varnishes, creams, pimples, make-up, textiles, shampoos, glass, mascaras, plastics, coating films, etc. The present invention also relates to a composition comprising a purine extract according to the invention. According to one embodiment of the invention, the composition comprises an amount of purine extract ranging from approximately 0.01% to approximately 95% by weight relative to the total mass of the composition, preferably from approximately 1% to about 25% w / w, more preferably about 5% to about 10 wt.%, based on the total weight of the composition. The extraction process according to the invention has the following advantages: use of raw material currently considered as a waste when fish scales are used; no use of toxic or polluting products such as liquids or organic solvents; the product according to the invention is pure, and in particular: according to one embodiment of the invention, it contains a small percentage of ash, which corresponds to the source of minerals; and o according to one embodiment of the invention, it does not contain amino acids or proteins, which may be allergenic; all products and by-products of the process are biodegradable. The process according to the invention can therefore be characterized as a "green" process, according to the definition of green chemistry given by the Environmental Protection Agency of the United States (EPA Agency). According to the EPA, the 12 principles of green chemistry are the following 25: (1) waste prevention; (2) saving atoms; (3) implementation of less dangerous chemical syntheses; (4) use of safer chemicals; (5) use of safer solvents; (6) minimize energy requirements; (7) use of renewable raw materials; (8) reduce derivatives whose production results in waste and energy consumption; (9) favoring catalysis; (10) use of biodegradable chemicals; (11) real-time pollution analysis; and (12) fundamentally safer chemistry, to prevent chemical incidents. Anastas and Zimmerman also provide a definition of green engineering in the article "Design through the 12 Principles of Green Engineering" (Environmental Science & Technology, 2003). According to one embodiment of the invention, the process according to the invention has a yield of between 1 g of purine (dry extract) per 10 kg of material comprising a purine and 1 kg per 10 kg, preferably between 10 g per 10 kg and 500 g for 10 kg, more preferably a yield of about 100 g of purine per 10 kg of material comprising a purine. According to one embodiment of the invention, the process according to the invention allows the extraction of about 100 g of guanine (dry extract) of 10 kg of fish scales, which corresponds to a yield of about 1%. . Furthermore, because of the absence of the use of chemicals or solvents, the treated material can be reused to extract other compounds, such as, for example, collagen or gelatin from Pisces. The present invention also relates to a pure purine extract of at least 20%, 30%, 40%, 50%, 60%, 70%, 80%, characterized in that it is not chemically synthesized. According to one embodiment of the invention, the purine extract according to the invention has an ash content of less than 20%, preferably less than 15%, more preferably less than or equal to 12% by weight relative to the total mass of the extract; and / or less than 2% of amino acids by weight relative to the total mass of the extract, preferably less than 1% w / w, more preferably less than 0.5% by weight relative to the total mass of the extract.

According to one embodiment of the invention, the purine extract according to the invention has a clarity L measured according to the CIE Lab model (also called L * a * b) greater than or equal to 85, preferably greater than or equal to 88, more preferably greater than or equal to 90, still more preferably greater than or equal to 94.

According to one embodiment of the invention, the purine extract according to the invention has the following characteristics: o component a (range of the red-green axis) varying from -1 to 1, preferably from -0.75 to 0.75, more preferably from -0.5 to 0.5; and / or o component b (range of the yellow-blue axis) varying from 0 to 15, preferably from 2 to 12, even more preferably from 3.5 to 9.5. According to another embodiment of the invention, the purine extract according to the invention has the following characteristics: o component a (range of the red-green axis) varying from 0 to 1, preferably from 0.3 to 0.7 more preferably from 0.35 to 0.65; and / or o component b (range of the yellow-blue axis) varying from 0 to 15, preferably from 4 to 8, even more preferably from 5.4 to 6.9. According to one embodiment of the invention, the purine extract according to the invention has a residual hydrogen peroxide content of less than 50 mg / L, preferably less than 20 mg / L, even more preferentially less than 10 mg / L.

BRIEF DESCRIPTION OF THE FIGURES FIG. 1: Amino acid profile determined by gas chromatography. (A) reference sample. (B): sample obtained by the process of the invention. Figure 2: Micro-RAMAN spectra (A) of the reference guanines (Bioingemar and SIGMA), (B) guanine extracted and bleached with hydrogen peroxide according to the process of the invention, and (C) guanine extracted and bleached with hydrogen peroxide according to the process of the invention after washing with 10% citric acid.

FIG. 3: FE-SEM image (A) of guanine extracted and bleached with hydrogen peroxide according to the process of the invention, and (B) guanine extracted and bleached with hydrogen peroxide according to the process of FIG. invention after washing with 10% citric acid.

Figure 4: Analysis of the whiteness of the guanine extracted according to the method of the invention (Lot 1 to Lot 5), or control guanine (Bioingemar and SIGMA). EXAMPLES The present invention will be better understood and interpreted in view of the examples below.

Example 1: Extraction Process The herring scales were harvested from the herring fishing boats. The first analyzes of guanine scales by RAMAN spectroscopy showed the presence of guanine in the scales from the plant. Equipment Class of material Description equipment - 7L bioreactors with stirrers (NBS-Bioflo110) - continuous flow centrifuge (ThermoSorvall-Contifuge Stratos) - turntable - oven raw material - frozen herring scales (Connors bros) chemicals - sarkosyl 30% (m / v) (Charles Tenant Co-Hamposyl L30) - Peroxide 35% (m / v) (Sigma-349887) others - sieves (mesh 3 mm and 100 μm) - 20L PTFE boilers - spatulas / nacelles - magnetic bars , beakers - Indicator Strips Quantofix peroxyd 100 (Sigma-37206-1EA) Method The extraction process consists of the following steps: 1. A bag of approximately 10 kg of herring scales is thawed at room temperature. 2. A volume of 1.5 L of flakes is used per reactor of 7L Bioflo110, the flakes 5 are washed with 3-4 volumes of cold water. This washing is done by placing the scales in a sieve (3 mm mesh) and rinsing them with a medium-flow water jet. 3. For each 1.5L scale portion, a 1% (w / v) water / sarkosyl solution is added to obtain a final volume of 5.5L per reactor. An agitator motor is installed on the apparatus and a stirring speed of 700 rpm is applied to the mixture for a period of 30 minutes. This incubation is performed at room temperature. 4. The resulting mixture is screened (mesh 3 mm) in order to remove the maximum of solid impurities, mainly herring scales. The scales in the sieve are rinsed with water with 1 volume of water (by volume of scales) in order to recover the maximum of guanine. A second sieving step is performed on the solution with a nylon filter (mesh 100 μm) in order to remove the larger black particles that are in the mixture. 5. The guanine extract is then centrifuged at a speed of 6000 rpm and a flow rate of 120 ml / min. The temperature of the rotor is maintained at 4 ° C. The rotor can hold about 400 g of pellet. 6. The recovered pellet is weighed and then resuspended in 2% (v / v) hydrogen peroxide solution. This incubation is carried out overnight with stirring (magnetic bar) at room temperature. 7. The peroxide / guanine solution is diluted 1/3 with water and centrifuged at a rate of 7000 rpm and a flow rate of 210 ml / min. The temperature of the rotor is maintained at 4 ° C. The pellet should be rinsed with water until a peroxide value of <10 mg / L (<10 ppm) is obtained. 8. The pellet recovered is then weighed and dried in an oven at a temperature of 45-50 ° C for a period of 16 to 24 hours.Once the dried product is homogenized with the aid of a mortar and the product final is weighed and analyzed.

EXAMPLE 2 Characterization of the Product Obtained by the Process of the Invention Methods The guanine sample obtained by the method of Example 1 below was characterized in the following manner: Determination of the mineral matter was performed on the guanine sample in comparison with the Bioingémar reference sample. Ash dosing was carried out by drying in an oven at 650 ° C overnight, followed by weighing. Analysis of the amino acid profile The amino acid profile was determined by gas chromatography using an EZ FAAST kit (PHENOMENEX). RAMAN Spectrometric Analysis and Scanning Microscopy RAMAN Microscopy and Scanning Electron Microscopy Analysis Raman micro-spectroscopic analysis of guanine samples extracted from herring scales from a commercial guanine sample (Sigma, sample # 1 ) and a sample of guanine extracted from salmon scales and marketed by Bioingemar (sample # 2) was performed using a laser with a wavelength of 632.8 nm. This choice was made in order to detect the vibration modes specific to the network modes that occur in the wavelength range below 200 cm-1. In addition, micro Raman analysis was performed using the 100x and 10x objectives. The 100x objective is used to interrogate a very narrow region of the sample (about 1 μm in diameter), while the 10x objective is used for the analysis of a larger area of the sample. Therefore, the Raman spectra obtained with the 100x objective are concentrated only on parts of the sample where some opalescence is seen; while the Raman spectra obtained with the 10x objective are focused on a large area of the sample involving the places where the impurities are present. Scanning electron microscopy analyzes were performed using Hitachi's very high resolution 54800 system. The system makes it easy to image samples on non-conductive substrates using an accelerating low voltage mode. Typically, the working distance was 3.2 mm, the acceleration voltage was 700 to 1000 V with an emission current of 2300 to 5000 nA, and the magnification was 20k to 110k. Guanine samples extracted from herring scales were mounted on 15 mm diameter aluminum rods.

Analysis of Colorimetric Parameters in the Lab System The colorimetric parameters of the products were measured using a MiniScan EZ portable colorimeter (HunterLab, VA, USA). The values of L * a * b * in the CIELab76 system were measured as an indicator. The value of clarity L is correlated with the whiteness of the particle. The closer it is to 100, the more white the particle is.

According to another protocol, the guanine solids content is placed in an eyeshadow cup, compacted at a pressure of 100 bars and then measured using a MINOLTA CM-2002 spectrocolorimeter (D65 / 10 °, specular component mode). included). The values of L, C, a and b are measured. Results Determination of the mineral matter The ash content of the final product is 12%. Amino Acid Profile Amino Acid Profile of the Bioingemar Reference (Figure 1A) Figure 1A shows that 2 main peaks are identified: the first corresponds to an elution at 1.61 minutes, and represents 90, 32% of the product, then that the second corresponds to an elution at 1.90 minutes and represents 9.68% of the product.

The first peak is not an amino acid, it is probably guanine. The second peak (IS) is norvaline (the internal standard). There does not seem to be any trace of amino acids in this sample. Amino acid profile of the sample obtained by the method of Example 1 (FIG. 5B) FIG. 1B shows that, again, 2 peaks are identified. In this sample, there does not seem to be any traces of amino acids. RAMAN Microspectroscopic Analysis and Scanning Electron Microscopy (FESEM) Figure 2A shows the micro-RAMAN spectra obtained for the reference guanines (Bioingemar and SIGMA). Figure 2B shows the micro-Raman spectrum of guanine extracted from the scales and bleached with hydrogen peroxide according to the method of the invention, in comparison with the reference guanine samples (Bioingemar and Sigma). Figure 3A is the FE-SEM image of the guanine extracted from the scales which shows that the presence of Sarkosyl changes the morphology of the guanine crystals, which can disturb the RAMAN spectrum measured above. In order to avoid this disturbance, the guanine extracted according to the process of the invention was washed with 10% citric acid. A new micro-Raman spectrum was then determined (Figure 2C) and a new FE-SEM image was obtained (Figure 3B). Analyzes carried out in RAMAN micro-spectroscopy and electron microscopy confirm the presence of guanine crystals in the extracts obtained by the process of the invention. Whiteness Analysis The whiteness of 5 batches of guanine extracted according to the method of the invention (batches 1 to 5, method of example 1), and two "control" guanines (Bioingemar and Sigma) were measured. The results of this measurement are shown in Table 1 below and in Figure 4.

Table 1: Whiteness test L ab Lot 1 94,90 0,26 9,22 Lot 2 94,40 0,26 7,99 Lot 3 94,31 -0,26 6,91 Lot 4 94,47 -0, 02 5.84 Lot 5 95.11 -0.44 3.66 Bioingemar 97.35 0.70 8.06 Sigma 99.36 -0.10 4.83 As shown in Table 1 and Figure 4, all lots obtained by extraction by the process of the invention have a whiteness relatively equivalent to that of the Bioingemar sample and slightly less than that of the SIGMA reference.

Furthermore, similar values are obtained according to another colorimetric parameter measurement protocol in which the guanine solids content is placed in an eyeshadow cup, compacted at a pressure of 100 bar and then measured using a MINOLTA CM-2002 spectrocolorimeter (D65 / 10 °, specular component mode included). The values of L, C, a and b are measured. Bioingemar guanine lot A guanine lot B guanine lot CL 89.93 90.01 91.65 89.34 a -1.18 -1.48 -0.35 -0.05 b 7.81 6.8 6.35 8 , 97 C 7.9 6.96 6.36 8.98 Clarity values L close to 90 and equivalent to the reference (guanine Bioingemar) are also obtained. In conclusion, the natural guanine extracts obtained according to the process of the invention, from herring scales, make it possible to obtain a guanine having characteristics peculiar to its use, in particular in the field of cosmetology.

Example 3 Process of the Invention Comprising a Crystallization Step and Characterization of the Product Obtained The guanine extraction was carried out on three different batches, according to the following conditions: Lot # 1 Lot # 2 Lot # 3 Step Extraction Sarkosyl Concentration ( % m / v) 1 1 1 Agitation Forte Strong High Time (min) 30 30 Step First Centrifuge Speed Centrifugation 1 (xg) 11,000 11,000 11,000 Flow Centrifugation 1 (L / h) 100 100 100 Step Whitening Ambient Temperature Concentration hydrogen peroxide (% w / v) 1.5 1.5 1.5 time peroxide treatment (h) 16 20 2 stirring vigorous peroxide treatment no low agitation Step second centrifugation speed centrifugation 2 (xg) 11 000 NA NA centrifugation rate 2 (L / h) 100 NA NA Crystallization step in boiling water at 100 ° C boiling time treatment time (h) 0.5 0.75 1.5 stirring boiling water treatment weak weak weak filtration 100! am yes yes yes Eta eg Drying drying (° C) 50 50 50 Duration (hours) 16-24 16-24 16-24 dry weight (kg) 6.25 2.5 0.9 NA = Not applicable 5 The characterization of the product obtained gave the following results: Lot # Container # (kg) s L (kg) sb rest2an0t2 a * 1 1 1.25 95.34 0.47 6.96 <10 ppm 1 2 1.25 96.18 0.38 6.51 <10 ppm 1 3 1.25 95.50 0.50 6.12 <10 ppm 1 4 1.25 96.23 0.34 5.41 <10 ppm 1 5 1.25 95.53 0.63 5, 96 <10 ppm 2 6 1.25 96.33 0.44 6.91 <10 ppm 2 7 1.25 96.00 0.42 6.80 <10 ppm 3 8 0.9 94.51 0.62 5 , 98 <10 ppm * ppm per 100 mg of guanine / ml of water This example shows that the presence of a crystallization step in the process of the invention makes it possible to increase the whiteness of the product obtained.

EXAMPLE 4 Comparative Example (Process of the Invention vs. Method Described by LevyLior et al (Crystal growth &design;2008; 8 (2): 507-11) Methods Test carried out according to the Levy-Lior process: 1) 1.0 kg d Scales were rinsed on sieves with tap water for about 10 minutes. 2) Incubation of the scales in 5.0L of distilled water (final volume) and mixing at 500-600 rpm for 15 minutes. The extract is then sieved by wire mesh (mesh = 3mm) and nylon mesh (mesh = 100 μm). 3) Centrifugation for 30 minutes at 10,600 rcf (pump flow: 250 ml / min). 4) The pellets are dried in an oven at a temperature of 45 ° C for a period of 12-18 hours. Method according to the invention: 1) 1.0 kg of scales were rinsed on sieve with tap water for about 10 minutes. 2) Incubation of scales in 5.0 L (final volume) of 1% water / sarkosyl solution and mix at 500 rpm for 15 minutes. 3) Centrifugation for 40 minutes at 7000 rpm (pump flow: between 160 ml / min). 4) The pellets are dried in an oven at a temperature of 45 ° C for a period of 12-18 hours. Results Before drying, the Levy-Lior process makes it possible to obtain a 29.4 g guanine pellet. The pellet appears dense, with a gray aqueous residue layer and a dense brown residue layer. The method according to the invention allows it to obtain a guanine pellet of 103.6 g. The pellet is of medium density, with a gray aqueous residue layer. After drying, the Levy-Lior process allows the recovery of a dry pellet of 12.9 g, against 68.4 g for the process according to the invention.

Claims (10)

REVENDICATIONS1. A method of extracting a purine by at least one surfactant, preferably an anionic surfactant, a zwitterionic surfactant and / or a nonionic surfactant. 2. Method according to claim 1, characterized in that said purine is guanine, hypoxanthine or a mixture of guanine and hypoxanthine. 3. Method according to claim 1 or claim 2, characterized in that said purine is in crystalline form. 4. Method according to any one of claims 1 to 3, characterized in that the purine is extracted from a material of animal origin, preferably fish scales. 5. Method according to any one of claims 1 to 4, characterized in that the surfactant is an anionic surfactant, preferably selected from sarkosyl, disodium cocoyl glutamate or dipalmitoylethyl hydroxyethylmonium methosulfate. 6. Process according to any one of claims 1 to 5, characterized in that the surfactant is an amino acid derivative, preferably the surfactant is sarkosyl. 7. Method according to any one of claims 1 to 6, characterized in that it further comprises a bleaching step with a bleaching agent, preferably hydrogen peroxide. 8. Method according to any one of claims 1 to 7, characterized in that it further comprises a step of enzymatic digestion, preferably with a catalase .. Process according to any one of claims 1 to 8, characterized in that it further comprises a crystallization step, preferably in a solvent, more preferably in water. 10. Purine extract obtained by the process according to any one of claims 1 to 9. 11. Use of a purine extract according to claim 10 as a coloring agent. 12. Composition comprising the extract according to claim 10. 13. purine extract according to claim 10, characterized in that it is at least 20% pure. 14. purine extract according to claim 10 or 13, characterized in that it has an ash content of less than 20%; and / or less than 2% of amino acids by mass relative to the total mass of the extract. 15. purine extract according to any one of claims 10, 13 and 14, characterized in that its color measured according to the model CIE Lab (also called L * a * b) has a component L (clarity) greater than or equal to 85, preferably greater than or equal to 90. 16. Purine extract according to any one of claims 10 and 13 to 15, characterized in that its color measured according to the CIE Lab model (also called L * a * b) presents the following characteristics: component a (range of the red-green axis) ranging from -1 to 1; and / or component b (range of the yellow-blue axis) ranging from 0 to 15. 17. Purine extract according to any one of claims 10 and 13 to 16, characterized in that it has a peroxide content residual hydrogen less than 50 mg / L.