ES2951407A1 - INSECTICIDE COMPOSITION TO CARRY TERPENES AND ESSENTIAL OILS, INSECTICIDE SOLUTION, METHOD OF OBTAINING AND ITS USE AS AN INSECTICIDE (Machine-translation by Google Translate, not legally binding) - Google Patents

Abstract

Insecticidal composition to transport terpenes and essential oils, insecticidal solution, method of obtaining and its use as an insecticide. In a first aspect, the invention relates to an insecticidal composition comprising an inclusion complex formed between a chitosan salt and a biologically active compound CBA. In a second aspect, the invention relates to the solution in water of the insecticidal composition. In a third aspect, the invention refers to the method of obtaining the insecticidal composition. In a final aspect, the invention relates to the use and form of application of the insecticidal composition or its solution as an insecticidal agent according to the first aspect of the invention to prevent, control and eliminate insect pests in agricultural crops, forestry and gardening. (Machine-translation by Google Translate, not legally binding)

Description

DESCRIPTION

INSECTICIDE COMPOSITION FOR VEHICULAR TERPENES AND OILS

ESSENTIALS, INSECTICIDE SOLUTION, METHOD OF OBTAINING AND ITS USE

AS AN INSECTICIDE

TECHNICAL SECTOR

The invention presented falls within the general scope of Chemistry, more specifically in Organic Chemistry, applicable in the agricultural, forestry and gardening sectors and deals with the use of organic compounds and/or of ecological origin that can act as emulsifiers of biologically active compounds (CBA's) insoluble in water, so that their bioavailability is significantly increased.

BACKGROUND OF THE INVENTION

Organic Chemistry is a wide-ranging field in continuous technological progress, applicable, among other branches, to the pharmaceutical, food and cosmetic industries, which need to evolve to meet new consumer demands and provide solutions adapted to very demanding needs. .

Its great potential allows the generation of new biologically active compounds (CBA) that have improved activity compared to current ones. Among them we can highlight those from nature, such as phytochemicals, bioactive compounds such as polyphenols, terpenes and essential oils present in plants or fruits. In most cases these CBAs are insoluble in water, with reduced bioavailability, stability and useful life. Among the characteristics mentioned, it is worth highlighting the concept of bioavailability, essential to guarantee that the compound has a use and is useful for the intended purpose. Unfortunately, the administration of these compounds often suffers from solubility and/or permeability problems (Thanki, K., Gangwal, R.P., Sangamwar, A.T., Jain, S., 2013. Oral delivery of anticancer drugs: challenges and opportunities. J Control. Release 170, 15-40).

Polyphenols, terpenes and essential oils are phytochemical compounds that can be beneficial, but the fact that they are insoluble in water prevents their benefit from being as desired. In general, they are soluble in alcohols, for example alcohol ethyl, but this fact severely limits its use in agriculture, the objective of this patent.

The technical literature shows that, in vivo and/or in vitro, polyphenols, terpenes and essential oils obtained from plants and vegetables are responsible for the following benefits:

- They reduce oxidative stress caused by biotic or abiotic factors.

- They reduce inflammation associated with oxidative stress.

- They have antifungal and antibacterial properties.

- They are insecticides.

- They are modulators of the immune system.

- Its environmental impact may be zero or reduced.

However, these compounds, due to their chemical nature, suffer from solubility and/or permeability problems and, therefore, have a very low bioavailability. In the context of the present invention, bioavailability is understood as the quantity and speed with which the active ingredient contained in a chemical formulation reaches its objective.

Based on this, one of the challenges of the chemical sector and, applicable in the agricultural sector, is the development of materials and substances to transport these phytochemicals. One of the main limitations that must be overcome in this sector is that many of the materials designed to transport other chemical substances present toxicity problems and, ultimately, have a limited effect.

Therefore, it would be desirable to develop new techniques for transporting biologically active compounds (CBA), in order to protect them and keep them stable during storage, also allowing a controlled release that increases their bioavailability. Such desirable technologies must meet the following requirements:

• Increase the solubility of CBA in aqueous media.

• Protect the active compound from degradation.

• Controlled release of CBA from the encapsulating matrix under specific conditions.

• Modify the physical characteristics of the CBA and facilitate its handling and application.

Of particular interest is the use of natural substances already authorized by the authorities and that have an additional effect on crops. Based on this, great efforts have been made to design a suitable vector to bioavailable a CBA using a gelling, coating or matrix. The method of administration, its toxicity, the product to be incorporated and the fact that they are substances recognized as safe or GRAS, natural and harmless, must be taken into account. Therefore, as a first choice, it is desirable to use ingredients naturally present in nature, thus avoiding the use of synthetic polymers that may present toxicity problems, even if they are slight. Certain natural polymers do not present these drawbacks, but their use additionally requires the development of production methods that are not complicated.

An illustrative example of an encapsulating agent is cyclodextrin; however, its main drawback is the difficulty in making CBA available and thus being active.

Another factor to take into account with respect to the bioavailability of phytochemicals is that these compounds are insoluble in water, so it is necessary to use an emulsifier, emulsifier or emulsifier, a substance that helps in the mixing of two immiscible substances or difficult to mix. In this way, by adding it, an emulsion is formed. Emulsifiers are surfactants with a structure similar to lipids (lipophilic) and another with an affinity for water (hydrophilic), which can be established around the boundary layers between the aqueous and oily components. Among the industrial emulsifiers, polysorbates (E432 Polysorbate 20, E433 Polysorbate 80, E434 Polysorbate 40, E435 Polysorbate 60 and E436 Polysorbate 65), sorbitan esters (E491 Sorbitan monostearate, E492 Sorbitan Tristearate, E493 Sorbitan monolaurate) stand out. , E494 Sorbitan monooleate and E495 Sorbitan monopalmitate), as well as E322 Soy lecithin, E444 Sucrose acetate isobutyrate, E471 Mono- and diglycerides of fatty acids and E476 Polyglycerol polyricinoleate. In agriculture, surfactants reduce droplet surface tension to increase coverage of some agrochemicals, and are generally composed of polysorbates and ethoxylated alcohols and water.

The European Commission is committed to the use of surfactants in the agricultural sector as a solution to promote good agricultural practices, reducing the amount of phytosanitary products necessary and enhancing the effect of growth regulators, biostimulants, fertilizers and deficiency correctors.

In the patent literature, it is worth highlighting, from the same inventors, patent ES2718225B2 where low molecular weight chitosan oligomers and steviol glycosides are used, and patent application P201931118, where an aqueous solution of a complex is described as encapsulating agents. for Equisetum arvense extract, Urtica spp extract, an amino acid and a combination thereof. In both cases, these compounds have been used as biostimulants and, in particular, as fungicides and bactericides.

However, there are no insecticidal compounds in the state of the art that can be classified as organic, and therefore of natural origin, biodegradable and in which none of the substances involved in the final compound are obtained by chemical synthesis. Insecticides are compounds used to control insect pests, but they usually have these disadvantages:

• It is necessary to make constant applications to control pests.

• When calculating the amount to be applied, it is necessary to solve technical problems such as temperature, UV radiation or humidity, which can affect the amount to be applied and its effectiveness over time.

• There are certain difficulties for its production worldwide, and more specifically, for the approval of its use due to its chemical nature.

• They can be toxic both for the vegetables and fruits where they are applied, as well as for those who ingest them later.

Based on this, the chemical industry has seen the need to develop insecticides that overcome the disadvantages, presenting at the same time high effectiveness and environmentally friendly obtaining and application, which can be called green or ecological chemistry and which ranges from the manufacturing to the handling of the product.

Based on the above, there is a need in this technical field to develop new CBA transportation systems that overcome the inconveniences mentioned and that store hydrophobic compounds, particularly those whose bioavailability entails difficulties, as is the case of terpenes and essential oils, and in general CBA's.

Finally, the properties that an insecticide must possess so that it can be applied in nature can be summarized in the following aspects:

• Should be effective against a wide range of insects.

• It should not be cumulative and non-biodegradable.

• It must be soluble in water to be sprayable.

• Have a pleasant, non-chemical smell.

• It must be chemically stable.

• Not be toxic to people or animals.

• Be environmentally safe, from manufacturing to application.

• It must be effective for an adequate period of time.

• Have a competitive price.

SUMMARY OF THE INVENTION

The present invention consists of a new delivery system for CBA's that are especially indicated for use in the production of insecticides. The delivery system described, apart from being in a harmless aqueous solution, has a natural composition, that is, without synthetic polymers or compounds and without the need to use surfactants, as is usual in the state of the art, The compounds that form it are also recognized as generally safe (GRAS), which totally favors its use in the treatment of crops, as it is a chemical complex that respects the environment and does not harm ecosystems as it does not include toxic substances. Thus, the invention presented can be applied particularly in agriculture, forestry and gardening.

Therefore, the inventors propose a new carrier system for CBA's, an insecticidal composition that comprises an inclusion complex formed between a chitosan salt and a biologically active compound CBA, which manages to improve its insecticidal and biostimulant capacity for vegetables and plants, applying natural, safe and biodegradable substances, very significantly improving its bioavailability by eliminating the presence of other chemicals essential for its dissolution, which are currently used in the agricultural sector.

In a first aspect, the invention relates to an insecticidal composition comprising by weight with respect to total:

a) 90 to 95% hydrogel formed by a chitosan salt, in the form of hydrochloride, acetate or citrate, and

b) 5 to 10% of at least one biologically active compound for agricultural application (CBA) that is selected from the group consisting of a terpene compound, an essential oil (composed mainly of terpenes) and a combination of the above.

In a second aspect, the invention relates to an insecticidal aqueous solution comprising the insecticidal composition according to the first aspect of the invention in an amount between 0.1 - 10% by weight of the total volume of the aqueous solution and water.

In a third aspect, the invention refers to a method for obtaining an insecticidal composition according to the first aspect of the invention, where said method comprises the following steps:

a) prepare a gel of chitosan and an organic or inorganic acid by a method comprising the following substeps:

Yo. mix between 1% to 5% by weight with respect to the total solid chitosan powder in water and stir until obtaining a homogeneous mixture;

ii. Add 1-5%, by weight with respect to the total mixture obtained in the previous stage, of an organic or inorganic acid, in the same amount as the chitosan powder used in the first step; and

iii. mix by stirring until the hydrogel is obtained;

b) add at least one biologically active compound and mix by sonication until a homogeneous composition is obtained at a temperature between 30°C-50°C, for 5 to 15 minutes.

In a fourth aspect, the invention relates to a method for obtaining an insecticidal aqueous solution according to the second aspect of the invention that comprises mixing water and 0.1-10% of the insecticidal composition object of the invention by stirring.

In a final aspect, the invention relates to the use of a solution according to the second aspect of the invention to prevent, treat and/or eliminate insect pests.

BRIEF DESCRIPTION OF THE DRAWINGS

At the end of this document, chemical structures of the inclusion complex object of the invention and preferred embodiments of the present invention have been shown for illustrative and non-limiting purposes. These diagrams are intended to complement the description of the invention in a summarized manner:

• Figure 1.- Image of the developed structure and internal energy of chitosan hydrochloride.

• Figure 2.- Image of theoretical model of complex formation between the chitosan hydrochloride molecule and limonene as CBA.

• Figure 3.- Three-dimensional model of the inclusion complex between the chitosan hydrochloride molecule and the limonene molecule.

• Figure 4.- a) Image of the developed structure and b) the spatial developed structure of a-pinene.

• Figure 5.- a) Image of the developed structure and b) the spatial developed structure of p-pinene.

• Figure 6.- a) Image of the developed structure and b) the spatial developed structure of Mircene.

• Figure 7.- a) Image of the developed structure and b) the spatial developed structure of Limonene.

• Figure 8.- a) Image of the developed structure and b) the spatial developed structure of Linalool.

• Figure 9.- a) Image of the developed structure and b) the spatial developed structure of Timol.

• Figure 10.- a) Image of the developed structure and b) the spatial developed structure of Carvacrol.

• Figure 11.- a) Image of the developed structure and b) the spatial developed structure of Geraniol.

DETAILED DESCRIPTION OF THE INVENTION

As explained above, the inventors propose a new CBA delivery system that is especially indicated for use in the production of natural and biodegradable insecticides. This is achieved through the use of polymeric substances obtained from a natural compound such as chitin, but applied in its gelled form in the form of chitosan hydrochloride, acetate or citrate, which forms a concentrated aqueous hydrogel, which allows its subsequent dissolution in water up to a percentage that allows its use in agriculture, forestry or gardening.

Products of invention

In a first aspect, the invention relates to an insecticidal composition comprising by weight with respect to the total:

a) 90-95% hydrogel formed by a chitosan salt, in the form of hydrochloride, acetate or citrate, and

b) 5-10% of at least one biologically active compound (CBA) for application in agriculture, forestry and gardening that is selected from the group consisting of a terpenic compound, an essential oil (composed mainly of terpenes) and a combination of the previous.

Thus, the present invention consists of an insecticidal composition especially indicated for the preparation of a new delivery system for a biologically active compound (CBA) for application in agriculture, forestry or gardening, especially indicated for use in the prevention, control and elimination of insect pests.

It should be noted that the insecticidal composition, according to the first aspect of the present invention, has an effective insecticidal capacity, surprisingly combined with its biodegradable characteristic. The inventors have been able to verify that thanks to the chemical composition it is capable of eliminating insect pests from the families Aphididae, Aleyrodinae, Cicadellidae, Tetranychidae, Curculionidae, Muscidae and a combination of the above, and in a completely effective way once said composition must be diluted in water to be applied, as described in this document.

This technical effect of the present invention overcomes the problem that the agricultural sector has to face in relation to current insecticides. Currently, the continuous use of pesticides, insecticides and herbicides incorporated into the soil poses the technical problem of their accumulation, and they can be toxic to land and aquifers. Therefore, the high effectiveness of the product of the present invention, together with its reduced durability, makes it a truly advantageous product compared to known insecticides.

To this end, the product described in this document comprises effective natural components, thus avoiding the use of chemical components responsible for toxic effects on the environment in general.

In particular embodiments of the present invention, the insecticidal composition may comprise chitosan hydrochloride, acetate or citrate. These options are equally effective alternatives. In preferred embodiments of the present invention, the insecticidal composition comprises between 90-95% by weight of chitosan hydrochloride, acetate or citrate and 5 to 10% of CBA's in the form of terpenes or terpene oils. In preferred embodiments, the insecticidal composition may comprise 90%, 90.5%, 91%, 91.5%, 92%, 92.5%, 93%, 93.5%, 94%, 94.5% or 95 % by weight of chitosan hydrochloride, acetate or citrate.

In the context of the present invention, chitosan is a biostimulant, that is, a substance that alters plant processes, improving its performance, being known for its capacity as a defense inducer. In particular, chitosan hydrochloride gel is known, which is accepted as a basic substance and approved at the European level (document SANCO/12388/2013), as an eliciting substance and with fungicidal and bactericidal effects, via stimulation of the defenses of the plants, in accordance with Implementing Regulation (EU) 2021/1446 and Plant Protection Products Regulation (EC) 1107/2009.

Chitosan molecules are capable of activating the SAR (System Acquired Resistance) and HR (High sensitive Response) system of plants. Both processes are key in the defense arsenal available to plants. These systems work by stimulating general vigor and producing phytoalexins and proteins related to the defense of different pathogeneses. In detail, it has effects such as stimulator of vegetative growth, in root production, in flowering, in the absorption and mobility of nutrients, in the promotion of plant structures (degree of lignification and suberization), in the synthesis of biochemical compounds, but also reduces abiotic stress and the spread of the disease in the plant. In botany, the elicitor quality refers to a group of compounds that act as signaling molecules that intervene in internal biological processes. A theoretical model of the chitosan molecule is offered, whose internal energy is 173.15 Kcal/mol. (See figure 1)

Likewise, in the context of the present invention, the term biologically active or bioactive compound (CBA) is that natural chemical substance found in plants, as well as in their derived products (for example, in flour, in oil. ..), in small quantities, and that have a certain effect on living organisms.

It should be noted at this point that a high number of CBA's are insoluble or have a very reduced solubility in water. To avoid this, solid-state encapsulation techniques of chitosan powder with CBAs are known. However, the fact that the object of the invention is the aqueous phase of the concentrated chitosan hydrochloride gel is the basis for ensuring the solubilization of the CBA, so that in subsequent dilutions in water the water solubility of the CBA is maintained, which It is an essential condition for its applicability.

In particular embodiments of the present invention, the insecticidal composition object of the present invention comprises at least one biologically active compound that is selected from the group consisting of a terpenic compound, an essential oil and a combination of the above. In preferred embodiments of the present invention, the insecticidal composition comprises a biologically active compound (CBA) in an amount between 5-10% by weight with respect to the total. In more preferred embodiments, the amount of CBA may be 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5% or 10%.

In other particular embodiments of the present invention, the insecticidal composition may comprise a terpene compound which in turn is selected from a group consisting of limonene, thymol, myrcene, pinene, eucalyptol, caryophyllene, linalool, geraniol, carvacrol and a combination of the previous ones. In preferred embodiments, the compound Terpenic is a monoterpene, so said terpenic compound can be limonene, thymol, linalool, geraniol, carvacrol or a combination of the above. In a more preferred embodiment, the terpene compound is limonene.

In the context of the present invention, terpenes and isoprenoids are a class of organic compounds derived from isoprene, a hydrocarbon with 5 carbon atoms. Traditionally they have been considered derivatives of 2-methyl-butadiene, better known as isoprene. This "isoprene rule" has allowed them to be classified and studied, but terpenes are actually derived from mevalonic acid, which comes from acetyl coenzyme A. Terpenes are the main constituent of the essential oils of some plants and flowers, such as lemon and lemon. Orange tree.

In the context of the present invention, monoterpenes are a class of terpenes that consist of two isoprene units and have the molecular formula C ⁱ 0H16. Monoterpenes can be linear (acyclic) or contain rings (monocyclic and bicyclic). Modified terpenes, such as those containing oxygen functionality or lacking a methyl group, are called monoterpenoids.

Preferably, the composition according to the first aspect of the invention may comprise terpene compounds exclusively or in combination with the other biologically active compounds described herein.

It is well known that terpene compounds have a complex chemical composition. They are compounds with a very low boiling point and present a great limitation derived from their insolubility in water, so it is necessary to dissolve them in an amount of surfactant of at least 70% by weight with respect to the total solution. Additionally, complex encapsulation methods with biopolymers or polyelectrolytes based on chitosan-alginate are described in the technical literature, which require cross-linking agents such as tripolyphosphate, which greatly increases the cost of the use of terpene compounds in Agriculture.

For reasons of environmental sustainability, this type of surfactant is not suitable for prolonged use and in any case, its use is expensive. Therefore, the present invention is presented as a much more advantageous alternative compared to the current use of these surfactants, since they carry the risk of toxicity in crops, in soils intended for agriculture, forestry and gardening in general.

Particularly, the composition comprises terpene compounds, and even more preferably, it comprises limonene, which is extracted from citrus peel. In this regard, the inventors have been able to verify that limonene, when found as the active ingredient of the solution, can be solubilized without the need to add a solvent or surfactant, which represents a very surprising advantage with respect to other insecticides that include this terpene compound. but it must be accompanied by a solvent as essential, as explained in the previous paragraph.

Therefore, the inventors propose a very advantageous solution with respect to the insecticides currently used in the sector, since with a simple mixture of the components of the insecticidal solution a very stable product is obtained and, consequently, it is transported in a more elemental way than methods based on polyelectrolytes or other more complicated encapsulation methods, with subsequent economic savings. Although it is known that the stability of solutions can be improved by adding a surfactant agent, for reasons of environmental sustainability the product object of the invention does not contain them in its composition.

A great advantage of this complex in aqueous solution is, therefore, that it does not require the incorporation of emulsifiers or surfactants to improve its solubility and bioavailability, compared to that described in the state of the art.

In particular embodiments, in the insecticidal composition, according to the first aspect of the invention, the CBA for application in agriculture, forestry or gardening is an essential oil and is selected from the group consisting of citrus oil, thyme, pine, lavender, oregano and a combination of the above. In other particular embodiments, the insecticidal composition may comprise essential oils exclusively or in combination with the other biologically active compounds described herein.

Essential oils are understood to be those products that are concentrates of plant raw material, intensely aromatic, non-greasy, volatile and light, obtained directly from plants, roots, flowers, leaves, trees, and that preferably in the present invention, comprise a high percentage of terpene compounds. In preferred embodiments of the present invention, the amount of terpene compounds is between 5 and 10% by weight with respect to the total. In preferred embodiments, these oils may comprise between 90 and 95% terpenic compounds by weight with respect to the total.

It has been verified that thanks to the hydrogel according to the first aspect of the invention, the solubility in water and consequently the bioavailability of the CBA's described in the present document and preferably, the terpene compounds, and of even more preferred form, limonene. Furthermore, the insecticidal composition allows insoluble CBAs to be solubilized or increases the solubility in those products that are partially soluble in water.

Additionally, the insecticidal composition object of the present invention presents a series of advantages with respect to other coating or encapsulation systems used in the agricultural sector, such as the surprising ability to keep the CBAs stable during storage, facilitating their application in the agricultural sectors. , food, pharmaceutical and cosmetic.

In a particular aspect of the present invention, the pH of the insecticidal composition is between 1.5 to 4.5. In preferred embodiments, the pH is between 1.5 to 3.5 and more preferably, 1.5 to 2.5. In particular embodiments of the present invention, the pH of the insecticidal composition may be 1.5, 2, 2.5, 3, 3.5, 4, or 4.5.

In another particular embodiment of the present invention, the viscosity of the insecticidal composition is between 0.05 to 1 Pas, and, preferably, between 0.08 to 0.8 Pas. In preferred embodiments, solution viscosity may be 0.05 Pas, 0.06 Pas, 0.07 Pas, 0.08 Pas or 0.09 Pas. In other preferred embodiments, the viscosity may be 0.1 Pas, 0.2 Pas, 0.3 Pas, 0.4 Pas, 0.5 Pas, 0.6 Pas, 0.7 Pas, 0.8 Pas, 0 .9 Pas or 1 Pas.

In a preferred embodiment, the insecticidal composition may comprise a preservative agent that is potassium metabisulfite in an amount between 0.1 to 0.5% by weight with respect to the total of the insecticidal composition. In even more realizations Preferred, the amount of potassium metabisulfite may be 0.1%, 0.2%, 0.3%, 0.4% or 0.5%.

In a second aspect, the invention also relates to an insecticidal aqueous solution comprising the insecticidal composition according to the first aspect of the invention in an amount between 0.1 - 10%, by weight of the total volume of the aqueous solution, and water, being more preferred between 1% to 8% and even more preferred between 2% to 5% by weight with respect to the total volume of the aqueous solution. In particular embodiments, the amount of the insecticidal composition according to the first aspect of the invention can be found in an amount of 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8% or 0.9%, and in other preferred embodiments it can be found in an amount of 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8% or 9%.

In preferred embodiments of the present invention, the insecticidal composition allows successive dilutions of the CBA, that is, dilutions are made with very high amounts of water, and has the surprising effect that said CBA remains soluble, without precipitating within the water or to form bubbles on the free surface of the liquid.

Therefore, as described in this document, thanks to the chitosan hydrogel, the CBA maintains its solubility in the solution of the insecticidal composition in water even in quantities of 1 liter of the composition in quantities of water between 50 liters. to 200 liters. In particular embodiments, the amount of water used to dissolve 1 liter of the insecticidal composition can be 50, 60, 70, 80, 90 or 100 liters. In other particular embodiments, the amount of water added to form the insecticidal aqueous solution is 100, 110, 120, 130, 140, 150, 160, 170, 180, 190 or 200 liters. Surprisingly, in all cases the inventors have been able to verify how the CBAs described in this document do not end up precipitating in the mixture as the amount of water in the solution is increased, something that is common to occur when trying to dissolving insoluble or poorly soluble products in large quantities of water, even when said insoluble products are accompanied by appropriate solvents. And it is thanks to this phenomenon that it is described here that CBA are bioavailable to be applied to crops and to have a greater insecticidal effect, as is the case of the present invention.

Based on what is described in this document, it is concluded that the composition according to the first aspect of the invention, as well as its aqueous solution according to the second aspect of the invention, are an optimal insecticidal product for application in agriculture, forestry and gardening. as demonstrated in the results of experiments carried out with these products, in which a decrease in pests of at least 90% has been observed compared to what initially existed.

In particular embodiments, the solubility of the CBA's increases with the concentration of the chitosan salt, so it should be around 4-5% in water, thus facilitating the formation of supramolecular structures in which the CBA is trapped. by weak or short-range molecular interactions with chitosan salt gel molecules (in the form of hydrochloride, acetate or citrate) in water.

As a basis to explain this phenomenon, a theoretical model of the formation of the inclusion complex between the chitosan hydrochloride molecule and limonene as CBA is offered herein, which is a preferred embodiment of the present invention. In this preferred case, the internal energy of the complex formed between the hydrogel formed by a chitosan salt, in the form of hydrochloride, acetate or citrate, and limonene is 30.48 Kcal/mol, which is lower than chitosan hydrochloride, and this demonstrates the formation of the complex and its stability (See Figure 2).

Furthermore, this insecticidal capacity of the insecticidal composition is even more surprising since the composition dissolved in water, according to the second aspect of the invention, when applied to an agricultural crop has a highly surprising insecticidal efficacy coupled with the fact that it has a very short durability. (and therefore is biodegradable), compared to other insecticides known in the state of the art.

In particular embodiments of the invention, the composition in aqueous solution in water has a durability of 1 to 5 days, thanks to the chemical nature of the insecticidal composition. In preferred embodiments, the durability is 2 to 4 days, and even more preferred 2 to 3 days, with no residue of said solution remaining in the agricultural crop or in the soil of said crop. Therefore, the inventors define the composition according to the first aspect of the invention, and its solution, according to the second aspect of the invention, as biodegradable products, which represents a very significant advantage in comparison with other insecticide products that can currently be found on the market.

In the context of the present invention, a biodegradable product is understood to be one that can decompose into its chemical elements, due to the action of humidity, solar radiation and biological agents, such as microorganisms and fungi, under environmental conditions. natural.

Method of obtaining the present invention

In a third aspect, the invention relates to a method for obtaining an insecticidal composition according to the first aspect of the present invention comprising the following steps:

a) prepare a chitosan hydrogel by a method that comprises the following substeps:

Yo. mix between 1% to 5% by weight with respect to the total solid chitosan powder in water and stir until obtaining a homogeneous mixture;

ii. Add 1-5%, by weight with respect to the total mixture obtained in the previous stage, of an organic or inorganic acid; and

iii. mix by stirring until the hydrogel is obtained;

b) add at least one biologically active compound and emulsify by sonication, which is the application of ultrasound, until a homogeneous hydrogel is obtained at a temperature in the range of 30° to 50°C, for 5 to 15 minutes.

It should be noted that chitosan is a molecule that is not soluble in water, so in step a.i) it is necessary to stir it until a homogeneous distribution of the powder is obtained in the water. In preferred embodiments, the amount of solid chitosan powder that is added in step a.i) can be 1%, 2%, 3%, 4% or 5%.

In preferred embodiments of the method for obtaining the insecticidal composition, the acid that is added in step a.ii) can be hydrochloric, acetic or citric acid. Likewise, the amount of acid is between 1% to 5% by weight with respect to the total solution obtained in step ai). In more preferred embodiments, the amount of acid added may be 1%, 2%, 3%, 4% or 5%.

In preferred embodiments of the present invention, the amount of acid that is added in step a.ii) should be equal to the amount of solid chitosan powder that is added in step a.i). This means that the amount of acid in step a.ii) can be 1%, 2%, 3%, 4% or 5%, but it will always be equal to the amount of solid chitosan powder that has been added in the stage a.i), to obtain the chitosan hydrogel.

In preferred embodiments of the method for obtaining the insecticidal composition, the mixture in step a.iii) is carried out by stirring until a homogeneous mixture is obtained, at a stirring speed typical of an industrial mixer, which can be between 3,000 - 5,000 rpm, preferably 3,000 - 4,500 rpm, and at room temperature. In the context of the present invention, ambient temperature is understood to mean the temperature between 18°C to 25°C, and more preferably between 20°C to 23°C.

In preferred embodiments of the method for obtaining the insecticidal composition, the sonication mixtures of step b) are made by applying ultrasound that can have a frequency between 15 to 25kHz. In preferred embodiments, the ultrasounds may have a frequency between 18 to 25kHz, more preferably, 20 to 25kHz. In other preferred embodiments, the ultrasounds may have a frequency of 15kHz, 16kHz, 17kHz, 18kHz, 19kHz, 20kHz, 21kHz, 22kHz, 23kHz, 24kHz or 25kHz.

In particular embodiments of the present invention, the development carried out is based on the formation of hydrogen bond bonds between the substances described, that is, the water-soluble and the insoluble. Hydrogen bonding is a strong electrostatic force when many molecules are joined together, as it provides great stability, but weaker than covalent bonding or ionic bonding. The action of the applied ultrasound is essential in the appearance of these bonds. This type of hydrogen bonding is formed for preferred embodiments where the terpene compound is linalool, thymol or carvacrol or the essential oil is rich in these terpene compounds as described previously herein. On the other hand, in the preferred embodiments where the terpene compound is limonene or pinene or essential oils rich in these terpene compounds, as described, an interaction of weak bonds is formed by hydrogen bonding.

In a preferred embodiment, the method object of the invention comprises an additional step c) that comprises adding potassium metabisulfite in an amount between 0.1 to 0.5% by weight with respect to the total of the insecticidal composition. In even more preferred embodiments, the amount of potassium metabisulfite may be 0.1%, 0.2%, 0.3%, 0.4% or 0.5%.

In a fourth aspect, the invention relates to a method for obtaining an aqueous insecticidal solution according to the second aspect of the invention that comprises mixing water and 0.1-10% of the insecticidal composition object of the invention by stirring until obtaining a solution. homogeneous, under standard conditions, which are the conditions specific to the application of products in the agricultural sector.

In preferred embodiments of the method for obtaining the insecticidal aqueous solution, they are obtained by stirring until a homogeneous mixture is obtained. It should be noted that the agitation conditions of the insecticidal aqueous solution are carried out under standard conditions, that is, under the application conditions used in the agricultural sector.

Although it is not decisive for the preparation of the insecticidal composition or the insecticidal aqueous solution, preferably the mixture of chitosan and the organic acid of step a.iii) to form the stable chitosan gel is carried out at a temperature comprised between 30-50°C. In preferred embodiments, step a.iii) is carried out at a temperature of 30°C, 31°C, 32°C, 33°C, 34°C, 35°C, 36°C, 37°C, 38° C, 39°C, 40°C, 41°C, 42°C, 43°C, 44°C, 45°C, 46°C, 47°C, 48°C or 49°C and 50°C.

Uses of the invention

In another aspect, the invention relates to the use of an aqueous insecticidal solution according to the second, to prevent, treat and/or eliminate insect pests on plants, in the agriculture, forestry or gardening sector. The type of pathogenic insects whose growth is prevented in plants with the use of the aqueous solution object of the invention is diverse and broad.

In a particular aspect of the present invention, the composition object of the invention is used to treat insects belonging to the order Hemiptera, suborder Homoptera and forming the family Aphididae, defined as aphids in Spanish and also flies. white spider, from the Aleyrodinae family, and leafhoppers, from the Cicadellidae family, as well as the red spider, ( Tetranychus urticae), from the Tetranychidae family. In another preferred embodiment, the composition object of the invention is used to treat insects belonging to the order Trombidiformes, suborder Acariformes and forming the family Tetranychidae, which are known by the common name of mites. It is also effective against the Cauí weevil, the rice weevil, which belong to the Curculionidae family, and the house fly, which belongs to the Muscidae family. Against these families of insects there is already evidence of activity and effectiveness of limonene, but this does not mean that it can have eliminative activity against other families.

In a particular embodiment, the aqueous solution is used to prevent, treat and eliminate insect pests by spraying the plant, at the foliar or root level. In addition, the application can also be applied at ground level to be applied at the root level by irrigation. Both uses preferably include applying an aqueous solution of the complex described on the crop, by spraying (foliar) or in the soil (root), although foliar application is always preferred because the effectiveness and absorption by the plant is always greater.

In particular embodiments of the present invention, the use involves the application of the insecticidal aqueous solution according to the second aspect of the invention, of 1 liter of aqueous solution of the complex per 50, 100 or up to 200 liters of water, although logically, as the effect is not altered by the volume of solution, it can be applied in any of the concentrations indicated herein.

All terms and embodiments described above are applicable to any aspect and embodiment of the invention. According to the present invention, the singular term "the", "the", "a", "one", "an", also refers to its corresponding plural "the", "the", "some". , "some", unless it appears from the context that the term clearly refers to a species in the singular. The term "comprises" or "comprising", as used herein, also describes "consists of " or "consisting of" in accordance with generally accepted patent practice.

EXAMPLES

Implementation procedure, theoretical determination and tests carried out in the field

The following invention is described by means of the following examples, which should be interpreted as illustrative and not limiting the scope of the invention.

1.1 Procedure for obtaining and characterizing an aqueous solution of the complex described in the present invention, with limonene as CBA.

The starting point is the production of chitosan hydrochloride gel, according to the following composition and procedure:

To 1 liter of water, 25 grams of solid chitosan powder are added and after 5 minutes of stirring so that the powder is "wet" and uniformly distributed in the water, the same amount by weight of commercial hydrochloric acid is added ( 37%), under intense stirring. This condition, even at room temperature, is necessary and sufficient for the formation of the chitosan hydrochloride gel in water. Once the gel is formed and stabilized, up to 100 grams of the terpene are added. limonene. Both substances are mixed by stirring and the resulting mixture is homogenized by introducing the sonicator head of the ultrasound equipment directly into the solution (with a frequency of 20 kHz). The sonication is carried out for periods of 2 minutes each, and a time of 10 minutes, not allowing the solution to heat above 50 ° C. The resulting solution, protected from light, has changed color until it acquires a white color similar to that of milk and is stored cold 4 -6°C overnight, to observe at the end of this period whether the emulsion has formed correctly. The already formed inclusion complex can then be packaged. The pH of the resulting solution cannot be altered to prevent undesirable precipitates from forming.

1.2. Analysis and theoretical determination of the formation of the inclusion complex.

This patent application provides a theoretical explanation that analyzes and explains the results obtained in the practices formalized last year.

The theoretical verification of the formation of the complex is based on the study of its energy content, which was calculated using the ChemBio3D Ultra 16.0 software (Perkin-Elmer Inc., Waltham, MA, USA) and the Molecular Mechanics calculation method ( MM2). Calculations were completed to obtain the energy of the 3D structure molecular, analyzing and exposing the energy of the basal state. The lower the final energy, the greater the stability of the molecule. MM2 is a method that is used to determine the geometry, molecular energies, vibrational spectra and enthalpies of formation of molecules in their basal state and is commonly used to determine the behavior of large molecules of biological and pharmaceutical importance. It is often used to determine the geometries of large molecules, such as those of biological and pharmaceutical importance, that were beyond the reach of more intensive methods based on molecular orbitals. For this reason, MM2 is not useful for modeling transition states of chemical processes with a large spectrum of experimental steps.

Calculations were carried out to obtain the energy of different conformations of the same 3D complex, analyzing and exposing those with the lowest formation energy. Different three-dimensional conformations were estimated for several CBAs. The total energy content, expressed in kcal/mol, of each molecule is described by the sum of the following interactions:

The developed structure and internal energy of chitosan hydrochloride are shown below, Table 1:

Table 1. Developed and special structure of chitosan hydrochloride and indication of its total energy content, expressed in kcal/mol.

Likewise, a theoretical model of the formation of the inclusion complex between the chitosan hydrochloride molecule and limonene, as CBA, is offered (see Table 2) through weak interactions between the molecules. The internal energy of the inclusion complex formed is lower than that of the original compound (chitosan hydrochloride), which demonstrates the formation of the complex and its stability.

Table 2. Developed and special structure of the inclusion complex between the chitosan hydrochloride molecule and limonene as CBA, and indication of its total energy content, expressed in kcal/mol.

1.3 Use of the aqueous solutions of the complex described in Example 1 and the results obtained in insect pest control.

This patent application provides a summary of the results obtained in the practices formalized last year, with field tests on the use of the inclusion complex formed between the chitosan hydrochloride gel with limonene, which was tested as an insecticidal agent. against the aphid ( Aphididae) and the red spider ( Tetranychus urticae) in hop crops ( Humulus lupulus), Veguellina de Órbigo, León, 2021, showing a reduction in insect pests in an interval between 70 and 90% in both cases, for two different concentrations and two degrees of dilution, which are explained in table 3.

The tests were carried out on hop crops at the end of August and beginning of September 2021, in various plots. In these months, on a regular basis and almost every year, aphid ( Aphididae) and red spider ( Tetranychus urticae) pests appear. Two aqueous solutions were tested, at 5 and 10% limonene and were applied so that, in a first test, 1 liter of concentrate was dissolved in 50 liters of water and in the second test, it was dissolved in 100 liters. Two applications were given, separated by an interval of 10 days, in the last week of August and the first week of September.

The results obtained are summarized below in Table 3:

Claims (15)

1. An insecticidal composition comprising an amount by weight with respect to the total: a) 90-95% hydrogel formed by a chitosan salt, in the form of hydrochloride, acetate or citrate, and b) 5-10% of at least one biologically active compound for application in agriculture, forestry and gardening that is selected from the group consisting of a terpene compound, an essential oil and a combination of the above. 2. The insecticidal composition according to claim 1, wherein the biologically active compound for application in agriculture, forestry and gardening is the terpene compound and is selected from the group consisting of limonene, thymol, myrcene, pinene, eucalyptol, caryophyllene, linalool, geraniol , carvacrol and a combination of the above. 3. The insecticidal composition according to claim 1 or 2, wherein the biologically active compound for application in agriculture, forestry and gardening is an essential oil and is selected from the group consisting of citrus oil, thyme, pine, lavender, oregano and combination of the above. 4. The insecticidal composition according to any one of claims 1 to 3, wherein the pH of the insecticidal composition is between 1.5 to 4.5. 5. The insecticidal composition according to any one of claims 1 to 4, wherein the viscosity of the insecticidal composition is between 0.05 and 1 Pas. 6. The insecticidal composition according to any one of claims 1 to 5, wherein the insecticidal composition comprises a preservative agent that is potassium metabisulfite in an amount between 0.1 to 0.5% by weight with respect to the total composition. 7. An insecticidal aqueous solution characterized in that it comprises an amount of 0.1 - 10% by weight of the total volume of the aqueous solution of the insecticidal composition defined in any one of claims 1 to 6 and water. 8. A method for obtaining an insecticidal composition defined in any one of claims 1 to 6, characterized in that it comprises the following steps: a) prepare a chitosan salt hydrogel in the form of hydrochloride, acetate or citrate, by a method that includes the following substeps: Yo. mix between 1% to 5% by weight with respect to the total solid chitosan powder in water and stir until obtaining a homogeneous mixture; ii. Add 1-5%, by weight with respect to the total mixture obtained in the previous stage, of an organic or inorganic acid; and iii. mix by stirring until the hydrogel is obtained; b) add at least one biologically active compound and mix by sonication, using ultrasound, until obtaining a homogeneous composition at a temperature between 30°C-50°C, for 5 to 15 minutes. 9. The method according to claim 8, wherein the amount of organic or inorganic acid that is added in step a.ii) is equal to the amount of solid chitosan powder that is added in step a.i). 10. The method according to claim 8 or 9, where, in step b), the ultrasounds have a frequency between 15 to 25kHz. 11. The method according to any one of claims 8 to 10, wherein the method comprises an additional step c) which comprises adding a preservative agent which is potassium metabisulfite in an amount between 0.1 to 0.5% by weight with with respect to the total insecticidal composition. 12. A method for obtaining an insecticidal aqueous solution defined in claim 7, characterized in that it comprises mixing water and 0.1-10% of the insecticidal composition defined in any one of claims 1 to 6, by stirring. 13. Use of the aqueous solution defined in claim 7, to prevent, treat and/or eliminate insect pests in agricultural crops, forestry and gardening. 14. The use according to claim 12, wherein the insects belong to the families that are selected from the group consisting of Aphididae, Aleyrodinae, Cicadellidae, Tetranychidae, Curculionidae, Muscidae and a combination of the above. 15. The use according to claim 13 or 14, wherein the aqueous solution is applied at the foliar level or at the root level.