BG302Y1 - Unwoven fabric containing hyaluronic acid derivatives - Google Patents

Abstract

The invention relates to biological materials made ofbiologically degrading, biologically compatible and biologicallyabsorbing unwoven fabrics. They find application in surgery forguiding the tissue regeneration and in pharmaceutics. The unwovenfabrics are made of fibres included in a binder. The binder andthe fibes contain esters of the hyaluronic acid used separately orin combination, or esters of hyaluronic acid in combination withesters of alginic acid or other polymers.20 claims, 2 figurs

Description

The utility model refers to a non-woven material containing hyaluronic acid derivatives used for medical and pharmaceutical purposes.

Hyaluronic acid is a natural heteropolysaccharide made up of alternating residues of D-glucuronic acid and N-acetyl-O-glucosamine. It is a linear polymer with a molecular weight of between 50,000 and 13,000,000 depending on the source from which it was obtained and the methods of preparation and determination used. In nature it is found in pericellular gels, in the main substance of connective tissues in vertebrates, where it is one of the main components, in the synovial fluid of the joints in the vitreous of the eye, in the tissue of the umbilical cord and in the comb of the cock.

BACKGROUND OF THE INVENTION

Specific fractions of hyaluronic acid are known with certain molecular weights that have no inflammatory effect and can therefore be used to stimulate wound healing, replace endobulbar fluids, or may be used in the treatment of joint pathology by intra-articular injection, as described in EP 138572 A of 25.07.1990.

EP 341745 A describes sanitary and surgical articles that can be used in particular in dermatology as artificial skin. They contain cross-linked acidic polysaccharides such as hyaluronic acid and its derivatives, alginic acid, carboxymethylcellulose, carboxymethylcytin.

Hyaluronic acid esters are also known in which all or some of the carboxylic acid groups are esterified, as well as their use in the pharmaceutical and cosmetic industries and in the field of biodegradable plastics, as described in US 4851521 and 4965353.

Hyaluronic acid is known to play an essential role in tissue repair processes, especially in the first stages of granulation, by stabilizing the coagulation network and controlling its degradation, favoring the restoration of anti-inflammatory cells such as polymorphonuclear leukocytes and monocyte cells fibroblasts and endothelial cells and orientation of subsequent epithelial cell migration.

It is well known that the use of hyaluronic acid solutions can accelerate the healing of patients affected by wounds from bedding, rubbing and burns.

The role of hyaluronic acid in the various phases that make up tissue repair processes is described by constructing the theoretical model by Weigel R.N. et al. "A model for the role of hyaluronic acid."

Studies aimed at the preparation of skin application products composed of hyaluronic acid esters, as such or in mixtures with other polymers, have led to the creation of different types of products. Among them are fabrics, such as gauze with different thickness (number of threads per centimeter), different sizes and with threads with different bottom (weight per 9000 m thread).

As described in US Patent Nos. 4,851,521 and 4,965,353, films of various thicknesses are available.

The use of such skin coating materials is limited by their hardness, which is determined more or less by the production method. However, there is always a problem when the material has to be cast on the surface to be coated.

Another disadvantage of using such materials is their poor ability to absorb, if at all, liquids such as disinfectant solutions, antibiotics, antiseptics, antifungal agents, proteins or, more generally, wound healing substances, even when they are not are dense or viscous.

The technical nature of the utility model

Plastic nonwovens have been created.

The nonwovens created are made up of hyaluronic acid esters used alone or in combination with one another or with other types of polymers. These materials are particularly soft and can be easily impregnated with various types of liquids.

Another area of application is clear from the detailed description and the attached figures. However, the detailed description and the foregoing examples representing preferred embodiments are given by way of illustration only because various modifications and modifications in the spirit and scope of the invention may be noticed by those skilled in the art of this detailed description.

Description of the figures

The foregoing and other objectives, features and advantages of the utility model will be better understood by the detailed description of the attached figures, all of which are given for illustration and not limitation, of which:

Figure 1 is a schematic diagram illustrating the steps involved in the manufacture of nonwovens;

Figure 2 shows the appearance of a non-woven textile material containing hyaluronic acid benzyl ester, HYAFF 11, obtained in Example 27.

The following detailed description is given to help those skilled in the art to perform the task practically. The description should not be construed as a limit on the utility model, since modifications and variations in the embodiments contemplated by those skilled in the art can be made without departing from the scope of the solution provided.

The contents of each of the cited literature are included in their entirety.

In the present solution, nonwovens with a weight between about 20 g / m ² and about 500 g / m ² and a thickness between about 0.2 and about 5 mm are created. The non-woven fabric can be described as a fabric made up of a large amount of fibers with a diameter varying between about 12 and 60 thousand in length between about 5 and about 100 mm, bonded by chemical coagulation or mechanically, or with a binder.

The non-woven fabric contains hyaluronic acid esters, used individually or mixed together in different ways. In addition, nonwovens may contain mixtures of fibers of hyaluronic acid esters with fibers of natural polymers, the ratio between which ranges from 1 to 100%, and such as collagen or co-collagen and glucoaminoglycans, cellulose, polysaccharides. in gel form, such as chitin, cytosan, pectin or pectic acid, agar, agarose, xanthan gum, gelan, alginic acid or alginates, polymanan or polyglycans, starches, natural resins or fibers derived from semi-synthetic natural poly derivatives eras, such as collagen cross-linked with agents such as aldehydes or carriers, dicarboxylic acids or their halides, diamines, cellulose derivatives, alginic acid, starch, hyaluronic acid, chitin or chitosan, gellan, xanthan, pectin or pectic acid, polyglycan polymnan, agar, agarose, natural rubbers, glucosaminogicans or fibers derived from synthetic polymers, such as polylactic acid, polyglycolic acid or copolymers of the same or derivatives thereof, polydioxanes, polyphosphazenes, polysulfone resins and polyurethane resins.

Non-woven materials having the above characteristics may be obtained from a multifilament yarn manufactured by conventional wet or dry twisting methods and then cut to desired lengths. The fiber mass is fed into a carding machine, which turns it into staple fibers. The latter are fed into a transverse grout, from which they appear as tissue of specific gravity.

The fabric may undergo chemical or mechanical bonding such as solvent soaking and subsequent coagulation, needle puncture, bonding agents of the same or different material from which the non-woven material is made, etc.

With regard to mechanical bonding, the principle of fiber reinforcement is based on the entanglement of the fibers and the increase in their friction obtained by compacting the fibrous tissue. The fibers are entangled by piercing the fabric vertically with the needles. These needles are mounted on machines and the fibrous material is fed to the needle punching machine and finally to the structuring machine that performs the surface structuring.

With respect to the binding agent treatments, the chemical binding treatment with the binding agents is performed on the fibrous tissue exiting the carding machine (Figure 1, item 9). The purpose of this treatment is to fix the fibers at their contact points. In the case of a non-woven material composed primarily of hyaluronic acid esters, this is achieved by atomizing 11 the fibrous tissue exiting the carding machine with a solution of hyaluronic acid esters in, for example, dimethyl sulfoxide (DMSO). Dimethyl sulfoxide, as a solvent of the fibers constituting the tissue, dissolves them and "warms" them in the subsequent coagulation bath 12. The fixed tissue is then washed 13 and dried 14.

The coagulation baths 3 and 15 are stainless steel and are in the form of a backward triangle, so that the extracted solvent that is formed can be kept in contact with the fresh coagulation solvent.

The coagulation process is basically an extraction process in which from a solution of polymer and solvent, solvent extraction and curing of the polymer can be accomplished by the addition of a second solvent, for example ethanol, in which the first solvent, for example dimethyl sulfoxide, is soluble and the polymer is insoluble.

The treatments described above have the effect of fixing the fibers to one another so as to obtain a structure composed of disorderly spaced, stacked fibers, forming a soft, stable material.

Therefore, the invention relates to a new class of non-woven products to be used in the field of medicine / formation as skin covers. These materials are fully or partially biocompatible and bioabsorbable and are composed of hyaluronic acid esters, used individually or mixed with one another, or with other natural or synthetic polymers. These materials are distinguished by their softness and ability to absorb liquids.

Such non-woven materials may be impregnated with, among other liquids, solutions of antibiotics, antiseptic and antimycotic agents or proteins. The term "non-woven material" encompasses practically materials, such as fabrics, felts, etc., composed of a large amount of fibers, chemically or mechanically interconnected. The material looks like fabric, though it is not woven in the exact sense of the word.

For illustrative purposes, some examples of the preparation of the nonwoven fabric of the invention are described below.

Hyaluronic acid esters

Hyaluronic acid esters useful for the invention are hyaluronic acid esters of aliphatic, arylaliphatic, cycloaliphatic or heterocyclic alcohols, in which all are esterified (so-called "total esters" or only part, so-called "partial esters" "), From carboxyl groups of hyaluronic acid and salts of partial esters with metals or with organic bases, biocompatible or pharmacologically acceptable.

Useful esters include esters derived from alcohols, which themselves have a marked pharmacological action. Saturated aliphatic line alcohols or simple cycloaliphatic line alcohols are also useful in the invention.

In the aforementioned esters, in which some of the carboxyl groups remain free, i.e. partial esters, they can be converted to salts with metals or organic bases such as alkali or alkaline earth metals or with ammonia or nitrogen-containing organic bases.

Most hyaluronic acid esters (“HY”), unlike HY itself, exhibit some degree of solubility in organic solvents. This solubility depends on the percentage of esterified carboxyl groups and on the type of alkyl group attached to the carboxyl group. Therefore, one HY compound with esterified all carboxyl groups has good solubility at room temperature, for example in dimethyl sulfoxide (HY benzyl ester is dissolved in dimethyl sulfoxide at 200 mg / ml). Most of the total esters of HY also have, unlike HY itself and especially its salts, low solubility in water and are essentially insoluble in water. The solubility characteristics, together with the noticeable highly elastic properties, make HY esters particularly preferred for use in multilayer membranes.

The aliphatic order alcohols to be used as esterifying agents for the carboxylic hyaluronic acid groups of the multilayer membranes of the invention are, for example, those with a maximum of 34 carbon atoms which may be saturated or unsaturated and which may be substituted by other free functional or functionally modified groups, such as amine, hydroxyl, aldehyde, ketogroup, mercaptan or carboxyl groups or from groups derived therefrom, such as hydrocarbyl or dihydrocarbylamino groups ( ttuk following the term "hydrocarbyl" is used to refer not only to monovalent radicals of hydrocarbons such as the type C _n H _{2n + 1,} but also bivalent or trivalent radicals, such as "alkylenes" C _n H _2n or "alkylidenes" C _n H _2n), ether or ester groups, acetal or ketal groups, thioether or thioester groups, and esterified carboxyl or carbamide groups and carbamide substituted by one or more hydrocarbyl groups, by nitrile groups or by halogens.

Of the aforementioned groups containing hydrocarbyl radicals, lower aliphatic radicals, such as alkyl of up to 6 carbon atoms, are preferred. Such alcohols may also be interrupted by a carbon chain of any heteroatom such as oxygen, nitrogen and sulfur. Alcohols substituted with one or two of said functional groups are preferred.

The alcohols of the aforementioned groups that are preferred for use are those with a maximum of 12, in particular with 6 carbon atoms, and in which the hydrocarbyl atoms in the aforementioned amino, ether, ester, thioether, thioester, acetal and ketal groups represent alkyl groups with maximum carbon atoms and also in the esterified carboxyl or substituted urea groups the hydrocarbyl groups are alkyl of the same number of carbon atoms and in which the amino or urea groups may be alkyleneamino or alkyleneurea groups with m maximum of 8 carbon atoms. Of these alcohols, particularly preferred are saturated and unsaturated alcohols such as methyl, ethyl, propyl and isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, tertiary butyl alcohol, amyl-, pentyl-, hexyl-, octyl-, nonyl-alcohol and dodyl especially those with a linear carbon chain, such as normal octyl and dodecyl alcohol. Of the substituted alcohols in this group are bivalent alcohols such as ethylene glycol, propylene glycol and butylene glycol, trivalent alcohols such as glycerol, aldehydes such as tartronic alcohol, carboxylated alcohols such as lactic acids, such as glycolic acid, malonic acids, malonic acids normal amino alcohol, aminopropanol, normal aminobutanol and their dimethylated and diethylated derivatives in the amino group, choline, pyrrolidinylethanol, piperidinylethanol, piperase inylethanol and the corresponding derivatives of normal propyl or normal butyl alcohol, monothioethylene glycol or its alkyl derivatives, such as ethyl derivatives in the mercaptan functional group.

Of the higher saturated aliphatic alcohols, cetyl and mericil alcohol are preferred, but for the purpose of the invention, the higher unsaturated alcohols with one or two double bonds are especially important, especially those contained in many of the terpenic affinity oils, such as citronellol, geraniol, geraniol , nerol, nerolidol, linalol, farnesol, phytol. Of unsaturated lower alcohols, it is important to consider allyl alcohol and propargyl alcohol. Of the aryl aliphatic alcohols are preferably those with only one benzene residue and those in which the aliphatic chain has a maximum of 4 carbon atoms and in which the benzene residue can be replaced by between 1 and 3 methyl groups or hydroxyl groups or halogen atoms , in particular chlorine, bromine and iodine, in which the aliphatic chain may be substituted by one or more functional groups selected from the group consisting of free amino groups or mono- or dimethylated or pyrrolidine or piperidine groups. Of these alcohols, benzyl alcohol and phenethyl alcohol are the most preferred.

Alcohols of the cycloaliphatic or aliphatic-cycloaliphatic order may be derived from mono- or polycyclic hydrocarbons, may have a maximum of 34 carbon atoms, may be unsubstituted and contain one or more substituents, such as those mentioned above for aliphatic alcohols. Of the alcohols derived from cyclic mono-ring hydrocarbons, those with a maximum of 12 carbon atoms, rings of the recommended number of carbon atoms between 5 and 7, which may be substituted, for example between one and three lower alkyl groups, such as methyl, are preferred. ethyl, propyl or isopropyl. The most preferred specific alcohols in this group are the following: cyclohexanol, cyclohexanediol, 1,2,3-cyclohexanetriol and 1,3,5-cyclohexantriol (phloroglucitol), inositol and alcohols derived from p-methane, such as carmentomol, menthol and α-γ-terpineol, 1-terpineol, 4-terpineol and piperitol or a mixture of these alcohols known as "terpineol", 1,4- and 1,8-terpine. Of the alcohols that are derived from hydrocarbons having condensed nuclei, such as thuyan, pinan or camphan, are preferred thuanol, sabinol, pinol hydrate, D and L-borneol, and D and L-isoborneol.

The aliphatic-cycloaliphatic polycyclic alcohols to be used for the esters of the invention are sterols, cholic acids and steroids, such as sex hormones and their synthetic analogs, especially corticosteroids and their derivatives. Therefore, the following may be used: cholesterol, dihydrocholesterol, epidihydrocholesterol, coprostanol, epicoprostanol, sitosterol, stigmasterol, ergosterol, cholic acid, deoxycholic acid, lithocholic acid, estriol, oestradinyl, estradiol, extradinol, extradiol 17-place derivatives such as 17α-ethynyl-estradiol or 7α-methyl-17α-ethynyl-estradiol, pregnenolone, pregnandiol, testosterone and its derivatives such as 17α-methyltestosterone, 1,2-dehydrotestosterone and 17α-methyl-1,2 dehydro estosterone, alkynylated derivatives at site 17 of testosterone and 1,2dehydrotestosterone, such as 17a-ethynyltestosterone, 17a-propynyltestosterone, norgestrel, hydroxyprogesterone, corticosterone, deoxycorticosterone, 19-norestosterone, 19-norstosterone, 19-norstosterone, 19-norstosterone , antihormones such as cyproterone, cortisone, hydrocortisone, prednisone, prednisolone, fluorocortisone, dexamethasone, betamethasone, parametamethasone, flumetasone, fluocinolone, fluocinolone, fluoprednilidene, clobetetacol, estrogen salon, alfadolone and bolasterone. The following compounds are useful as esterifying components for the esters of the invention: genins (aglycones) of cardioactive glycosides, such as digitoxigenin, gitoxygenin, digoxigenin, strophantinidin, tigogenin and saponins.

Other alcohols to be used in the invention are vitamins such as axeroptol, vitamins D ₂ and D ₃ , aneurine, lactoflavin, ascorbic acid, riboflavin, thiamine and pantothenic acid.

Of the heterocyclic acids, the following may be regarded as derivatives of the aforementioned cycloaliphatic or aliphatic cycloaliphatic alcohols if their linear or cyclic chains are interrupted by one or more, for example, between one and three heteroatoms selected, for example, from the group consisting of -O-, -S -, -N- and -NH-, and one or more unsaturated bonds may be present in these compounds, for example double bonds, in particular between one and three, thereby including heterocyclic compounds having aromatic structures. Examples include the following compounds: furfuryl alcohol, alkaloids and derivatives thereof, such as atropine, scopolamine, cinchonin, la-cinchonidine, quinine, morphine, codeine, nalorphine, N-butyl-scopolammonium bromide, aymalin, phenylethyl, phenylethyl ephedrine, isoproterenol, epinephrine, phenothiazine drugs such as perphenazine, pipothiazine, carphenazine, homophenazine, acetophenazine, fluophenazine and N-hydroxyethylpropamethazine chloride, thioxanthene drugs such as flupentixol and clopopentoxol, clopropothioxol, clopropovil , antiemetic, such as oxypendyl, analgesic, such as carbetidine, phenoperidine and methadol, hypnotic, such as etodroxysin, anorexic, such as benzydrol and difemetoxidin, weak tranquilizers such as hydroxysin, muscle relaxants, such as cinnamedrine, diphylin, chlorofen, mefenicene, mefenicen -diethyl-1,3-propanediol, gaifenesin, hydrocylamide, coronary vasodilators, such as dipidamol and oxyphedrine, adrenergic blocking agents such as propanolol, timolol, pindolol, bupranolol, atenolol, metroprolol, practolol such as 6-azuridine, cytarabine, fluoxidine, antibiotics, such as chloramphenicol, thiamphenicol, erythromycin, antiviral agents, such as idoxuridine, peripheral vasodilators, carbohydrates, carbohydrates, carbohydrates such as 2-p-sulfanilone ethanol.

In some cases, hyaluronic acid esters may be of interest, in which the ester groups are derived from two or more therapeutically active hydroxyl substances and all possible variants can naturally be obtained. Of particular interest are substances in which two types of different ester groups derived from hydroxyl drugs are present and in which the other hydroxyl groups are free, converted to a metal or base salt, and the bases themselves may also be therapeutically active, for example with the same or similar activity as that of the esterifying component. More specifically, it is possible to obtain hyaluronic acid esters derived, on the one hand, from an anti-inflammatory steroid, such as one mentioned above and, on the other, from a vitamin, alkaloid or antibiotic, as one of the above.

Method for the preparation of hyaluronic acid esters

Method A.

Hyaluronic acid esters can be prepared by known methods for esterifying carboxylic acids, for example by treating the free hyaluronic acid with the desired alcohols in the presence of catalytic substances, such as strong inorganic acids or ion-exchange agents of an acid type or with an esterifying agent to introduce the desired alcohol residue in the presence of inorganic or organic bases. As esterifying agents, those known in the literature may be used, especially esters of various inorganic or organic sulfonic acids, such as hydroacids, e.g. hydrocarbyl halides such as methyl or ethyl iodide or neutral sulfates or hydrocarbic acids, alphabets, carbonates, silicates, phosphites or hydrocarbyl sulfonates, such as methylbenzene or p-toluenesulfonate or methyl or ethyl chlorosulfonate. The reaction may be carried out in a suitable solvent, for example alcohol, preferably one corresponding to the alkyl group to be introduced into the carboxyl group. But the reaction can also be carried out in non-polar solvents such as ketones, ethers or dioxane, or in aprotic solvents such as dimethyl sulfoxide. For example, alkali metal, alkaline earth metal or magnesium hydroxide may be used as the base, as well as silver oxide or a basic salt of one of these metals, such as carbonate and organic bases, a tertiary nitrogen base such as pyridine or colidine. A base type ion exchange resin may also be used instead of a base.

In another esterification method, metal salts or salts with organic nitrogen bases are used, for example ammonium base or substituted ammonium salts. Salts of alkali or alkaline earth metals are preferably used, but salts of other metals may also be used. The esterifying agents in this case are also those mentioned above, and the same applies to the solvents. Preferably, aprotic solvents, for example dimethyl sulfoxide and dimethylformamide, are used.

In the esters free carboxylic groups of the partial esters obtained according to this or any of the following procedures, hereinafter described, may be converted into salts, if desired, by known "per se" methods. Method B.

Hyaluronic esters can also be prepared by a method which consists in treating the quaternary ammonium salt of hyaluronic acid with an esterifying agent, preferably in an aprotic organic solvent.

As organic solvents it is preferable to use aprotic solvents such as dialkylsulfoxides, dialkylcarboxamides, such as in particular lower alkyl dialkylsulfoxides with specially dimethylsulfoxide, and lower alkyl dialkylamides of lower aliphatic acids, such as dimethyl or diethylformamide or dimethyl or diethylacetamide.

Other solvents that are not always aprotic, such as alcohols, ethers, ketones, esters, especially aliphatic or heterocyclic alcohols and low boiling point ketones, such as hexafluoroisopropanol, trifluoroethanol and N-methylpyrrolidone, should be considered.

The reaction is preferably carried out in the temperature range between about 0 and 100 ° C, especially between about 25 and 75 ° C, for example at about 30 ° C.

The esterification is preferably carried out by adding portions of the esterifying agent to said ammonium salt in one of said solvents, for example dimethyl sulfoxide.

As the alkylating agents, those mentioned above, especially hydrocarbyl halogens, for example alkyl halogens, may be used. Preferred quaternary ammonium salts are preferably lower ammonium tetraalkylates, with alkali groups preferably between 1 and 6 carbon atoms. Tetrabutylammonium hyaluronate is most commonly used. These quaternary ammonium salts can be prepared by reacting a metal salt of hyaluronic acid, preferably one of those mentioned above, in particular the sodium or potassium salt, in aqueous solution with the salt quaternary ammonium base converted to salt.

An embodiment of the procedure described consists in the reaction of a potassium salt of hyaluronic acid dissolved in a suitable solvent such as dimethyl sulfoxide with a suitable alkylating agent in the presence of catalytically acting amounts of a quaternary ammonium salt such as tetrabutylammonium iodide.

To obtain hyaluronic acid esters, hyaluronic acids of any origin may be used, such as the acids extracted from the starting materials mentioned above, for example from a rooster comb. The preparation of these acids has been described in the literature: it is advisable to use purified hyaluronic acids. In particular, hyaluronic acids are used, including molecular fractions of integral acids, obtained directly by the extraction of organic materials with molecular weights varying over a wide range, for example, from about 90-80% (mol. Weight = 11.7-

10.4 million) to 0.2% (molar weight = 30,000) of the molecular weight of the integral acid having a molecular weight of 13 million, preferably between 5 and 0.2%. Such fractions can be obtained by various methods described in the literature, such as hydrolysis, oxidation, enzymatic or physical procedures, such as mechanical or radiation methods. Primary extracts are often obtained during the procedures described in the literature (for example, the article by Balazs et al. Published in Cosmetics & Toiletries). The separation and purification of the resulting molecular fractions is carried out by known techniques, for example by filtration through a molecular sieve.

In addition, purified fractions obtainable from hyaluronic acid, such as those described in EP 0138572, are useful.

The preparation of the hyaluronic acid salts with the above metals for the preparation of the starting salts for the special esterification procedure is carried out by known means, for example, by reaction between a hyaluronic acid with a stoichiometrically calculated amount of alkali hydroxides or with the basic salts of these metals as carbonates or carbonates.

In the partial esters, it is possible to convert to the salt all other carboxylic groups or only a portion thereof, by dosing the amounts of base to obtain the desired stoichiometric degree of salt formation. With the right degree of conversion to salt, esters with a wide range of different dissociation constants can be obtained, which will therefore be able to give the desired pH in solution or "in situ" when applied in therapy.

Examples of implementation of the utility model

The following examples explain the preparation of hyaluronic acid esters useful for multilayer membranes.

Example 1. Preparation of (partial) propyl ester of hyaluronic acid (HY) -50% esterified carboxyl groups 50% converted to salt carboxyl groups (Na)

12.4 g of the tetrabutylammonium salt of hyaluronic acid with a molecular weight of 170,000 corresponding to 20 mol of the monomer were dissolved in 620 ml of dimethyl sulfoxide at 25 ° C, 1.8 g (10.6 mol) of propyl iodide were added and the resulting solution was maintained at 30 ° C for 12 h.

A solution containing 62 ml of water and 9 g of sodium chloride was added and the resulting mixture was slowly poured into 3500 ml of acetone with constant stirring. A precipitate formed which was filtered and washed three times with 500 ml of acetone / water 5: 1 and three times with acetone and finally dried in vacuo for 8 hours at 30 ° C.

The product was then dissolved in 550 ml of water containing 1% sodium chloride and the solution slowly poured into 3000 ml of acetone with continuous stirring. A precipitate formed which was filtered and washed twice with 500 ml of acetone / water (5: 1) and three times with 500 ml of acetone and finally dried in vacuo for 24 hours at 30 ° C. 7.9 g of the title propyl ester are obtained. The ester groups were quantified using the method of R.H. Cundiff and P.C. Markunas [Anal. Chem. 33, 1028-1030 (1961)].

Example 2. Preparation of (partial) isopropyl ester of hyaluronic acid (HY) - 50% esterified carboxylic groups - 50% salt-converted carboxylic groups (Na)

12.4 g of the tetrabutylammonium salt of hyaluronic acid with a molecular weight of 160,000 corresponding to 20 mol of the monomer were dissolved in 620 ml of dimethyl sulfoxide at 25 ° C, 1.8 g (10.6 mol) of isopropyl iodide were added and the resulting solution was maintained for 12 h at 30 ° C.

A solution containing 62 ml of water and 9 g of sodium chloride was added and the resulting mixture was slowly poured into 3500 ml of acetone with continuous stirring. A precipitate formed which was filtered and washed three times with 500 ml of acetone / water (5: 1), three times with acetone and finally dried in vacuo for 8 hours at 30 ° C.

The product was then dissolved in 550 ml of water containing 1% sodium chloride and the solution slowly poured into 3000 ml of acetone with continuous stirring. A precipitate formed which was filtered and washed twice with 500 ml of acetone / water (5: 1) and three times with 500 ml of acetone, then finally dried under vacuum for 24 hours at 30 ° C.

7.8 g of the partial isopropyl ester of the title compound are obtained. Quantification of ester groups was performed using the method of R.H. Cundiff and P.C. Markunas [Anal. Chem. 33, 1028-1030 (1961)].

Example 3. Preparation of (partial) ethyl hyaluronic acid ester - 75% esterified carboxylic groups - 25% salt-converted carboxylic groups (Na)

12.4 g of the tetrabutylammonium salt of hyaluronic acid with a molecular weight of 250 000 corresponding to 20 mol of the monomer were dissolved in 620 ml of dimethyl sulfoxide at 25 ° C, 2.5 g (15.9 mol) of ethyl iodide were added and the resulting solution was added. maintained at 30 ° C for 12 h.

A solution containing 62 ml of water and 9 g of sodium chloride was added and the resulting mixture was slowly poured into 3500 ml of acetone with continuous stirring. A precipitate formed which was filtered and washed three times with 500 ml of acetone / water (5: 1), three times with acetone and finally dried in vacuo for 8 hours at 30 ° C.

The product was then dissolved in 550 ml of water containing 1% sodium chloride and the solution slowly poured into 3000 ml of acetone with continuous stirring. A precipitate formed which was filtered and washed twice with 500 ml of acetone / water (5: 1) and three times with 500 ml of acetone, then finally dried under vacuum for 24 hours at 30 ° C.

7.9 g of the partial isopropyl ester, the title compound, are obtained. Quantification of ester groups was performed using the method of R.H. Cundiff and P.C. Markunas [Anal. Chem. 33, 1028-1030 (1961)].

Example 4. Preparation of (partial) methyl hyaluronic acid methyl ester - 75% esterified carboxylic groups - 25% salt-converted carboxyl groups

12.4 g of the tetrabutylammonium salt of hyaluronic acid with a molecular weight of 80,000 corresponding to 20 mol of monomer were dissolved in 620 ml of dimethyl sulfoxide at 25 ° C, 2.26 g (15.9 mol) of methyl iodide were added and the resulting solution was maintained for 12 h at 30 ° C.

A solution containing 62 ml of water and 9 g of sodium chloride was added and the resulting mixture was slowly poured into 3500 ml of acetone with continuous stirring. A precipitate formed which was filtered and washed three times with 500 ml of acetone / water (5: 1), three times with acetone and finally dried in vacuo for 8 hours at 30 ° C.

The product was then dissolved in 550 ml of water containing 1% sodium chloride and the solution slowly poured into 3000 ml of acetone with continuous stirring. A precipitate formed which was filtered and washed twice with 500 ml of acetone / water (5: 1) and three times with 500 ml of acetone, then finally dried under vacuum for 24 hours at 30 ° C.

7.8 g of the partial isopropyl ester, the title product, are obtained. Quantification of ester groups was performed using the method of R.H. Cundiff and P.C. Markunas [Anal. Chem. 33, 1028-1030 (1961)].

Example 5. Preparation of hyaluronic acid methyl ester

12.4 g of tetrabutylammonium salt of hyaluronic acid with a molecular weight of 120,000 corresponding to 20 mol of monomer were dissolved in 620 ml of dimethyl sulfoxide at 25 ° C, 3 g (21.2 mol) of methyl iodide were added and the resulting solution was maintained for for 12 h at 30 ° C.

The resulting mixture was slowly poured into 3500 ml of ethyl acetate with continuous stirring. A precipitate formed which was filtered and washed four times with 500 ml of ethyl acetate and finally dried in vacuo for 24 hours at 30 ° C.

8 g of the ethyl ester product of the title are obtained. Quantification of ester groups was performed using the method of R.H. Cundiff and P.C. Markunas [Anal. Chem. 33, 1028-1030 (1961)].

Example 6. Preparation of hyaluronic acid ethyl ester

12.4 g of the tetrabutylammonium salt of hyaluronic acid with a molecular weight of 85000 corresponding to 20 mol of monomer were dissolved in 620 ml of dimethyl sulfoxide at 25 ° C, 3.3 g (21.2 mol) of ethyl iodide were added and the resulting solution was maintained in for 12 h at 30 ° C.

The resulting mixture was slowly poured into 3500 ml of ethyl acetate with continuous stirring. A precipitate formed which was filtered and washed four times with 500 ml ethyl acetate and finally dried in vacuo for 24 hours at 30 ° C.

8 g of the ethyl ester product of the title are obtained. Quantification of ester groups was performed using the method of R.H. Cundiff and P.C. Markunas [Anal. Chem. 33, 1028-1030 (1961)].

Example 7. Preparation of Hyaluronic Acid Propyl Ester

12.4 g of the tetrabutylammonium salt of hyaluronic acid with a molecular weight of 170,000 corresponding to 20 mol of monomer were dissolved in 620 ml of dimethyl sulfoxide at 25 ° C, 3.6 g (21.2 mol) of propyl iodide were added and the resulting solution was maintained for 12 h at 30 ° C.

The resulting mixture was slowly poured into 3500 ml of ethyl acetate with continuous stirring. A precipitate formed which was filtered and washed four times with 500 ml of ethyl acetate and finally dried in vacuo for 24 hours at 30 ° C.

8.3 g of the propyl ester, the title compound, are obtained. Quantification of ester groups was performed using the method of R.H. Cundiff and P.C. Markunas [Anal. Chem. 33, 1028-1030 (1961)].

Example 8. Preparation of (partial) butyl ester of hyaluronic acid - 50% esterified carboxylic groups - 50% salt-converted carboxylic groups (Na)

12.4 g of the tetrabutylammonium salt of hyaluronic acid, with a molecular weight of 620 000 corresponding to 20 mol of monomer, were dissolved in 620 ml of dimethyl sulfoxide at 25 ° C, 1.95 g (10.6 mol) of n-butyl iodide were added and the resulting solution maintained at 30 ° C for 12 h.

A solution containing 62 ml of water and 9 g of sodium chloride was added and the resulting mixture was slowly poured into 3500 ml of acetone with continuous stirring. A precipitate formed which was filtered and washed three times with 500 ml of acetone / water (5: 1), three times with acetone and finally dried in vacuo for 8 hours at 30 ° C.

The product was then dissolved in 550 ml of water containing 1% sodium chloride and the solution slowly poured into 3000 ml of acetone with continuous stirring. A precipitate formed which was filtered and washed twice with 500 ml of acetone / water (5: 1) and three times with 500 ml of acetone, then finally dried under vacuum for 24 hours at 30 ° C.

8 g of the partial butyl ester of the title compound are obtained. Quantification of ester groups was performed using the method of R.H. Cundiff and P.C. Markunas [Anal. Chem. 33, 1028-1030 (1961)].

Example 9. Preparation of (partial) ethoxycarbonylmethyl hyaluronic acid ester - 75% esterified carboxylic groups - 25% - carboxylic acid salt

12.4 g of the tetrabutylammonium salt of hyaluronic acid with a molecular weight of 180,000 corresponding to 20 mol of monomer were dissolved in 620 ml of dimethyl sulfoxide at 25 ° C, 2 g (15 mol) of tetrabutylammonium iodide and 1.84 g (15 mol) were added. ) ethyl chloroacetate and the resulting solution was maintained at 30 ° C for 24 h.

A solution containing 62 ml of water and 9 g of sodium chloride was added and the resulting mixture was slowly poured into 3500 ml of acetone with continuous stirring. A precipitate formed which was filtered and washed three times with 500 ml of acetone / water (5: 1), three times with acetone and finally dried in vacuo for 8 hours at 30 ° C.

The product was then dissolved in 550 ml of water containing 1% sodium chloride and the solution slowly poured into 3000 ml of acetone with continuous stirring. A precipitate formed which was filtered and washed twice with 500 ml of acetone / water (5: 1) and three times with 500 ml of acetone, then finally dried under vacuum for 24 hours at 30 ° C.

10 g of ethoxycarbonyl methyl ester - the title compound are obtained.

Quantification of the ester groups was performed using the method of R.H. Cundiff and P.C. Markunas [Anal. Chem. 33, 1028-1030 (1961)].

Example 10. Preparation of p-pentyl hyaluronic acid ester

12.4 g of the tetrabutylammonium salt of hyaluronic acid, with a molecular weight of 620 000 corresponding to 20 mol of monomer, were dissolved in 620 ml of dimethyl sulfoxide at 25 ° C, 3.8 g (25 mol) of n-pentyl bromide and 0.2 g were added. tetrabutylammonium iodide and the resulting solution was maintained at 30 ° C for 12 h.

The resulting mixture was slowly poured into 3500 ml of ethyl acetate with continuous stirring. A precipitate formed which was filtered and washed four times with 500 ml of ethyl acetate and finally dried in vacuo for 24 hours at 30 ° C.

8.7 g of the n-pentyl ester compound are obtained from the title.

Quantification of ester groups was performed using the method described on pages 169-172 by Siggia S. & Hanna J.G. “Quantitative Organic Analysis via Functional Groups” 4th Edition, John Wiley and Sons.

Example 11. Preparation of hyaluronic acid isopentyl ester

12.4 g of the tetrabutylammonium salt of hyaluronic acid with a molecular weight of 170,000 corresponding to 20 mol of the monomer were dissolved in 620 ml of dimethyl sulfoxide at 25 ° C, 3.8 g (25 mol) of isopentyl bromide and 0.2 g of tetrabutyl- ammonium iodide and the resulting solution was maintained at 30 ° C for 12 h.

The resulting mixture was slowly poured into 3500 ml of ethyl acetate with continuous stirring. A precipitate formed which was filtered and washed four times with 500 ml of ethyl acetate and finally dried in vacuo for 24 hours at 30 ° C.

8.6 g of the title isopentyl ester are obtained.

Quantification of the ester groups was performed using the method described on pages 169-172 by Siggia S. & Hanna J.G. “Quantitative Organic Analysis via Functional Groups” 4th Edition, John Wiley and Sons.

Example 12. Preparation of hyaluronic acid benzyl ester

12.4 g of the tetrabutylammonium salt of hyaluronic acid with a molecular weight of 170,000 corresponding to 20 mol of monomer were dissolved in

620 ml of dimethyl sulfoxide at 25 ° C, 4.5 g (25 mol) of benzyl bromide and 0.2 g of tetrabutyl-ammonium iodide were added and the resulting solution was maintained at 30 ° C for 12 h.

The resulting mixture was slowly poured into 3500 ml of ethyl acetate with continuous stirring. A precipitate formed which was filtered and washed four times with 500 ml of ethyl acetate and finally dried in vacuo for 24 hours at 30 ° C.

9 g of the benzyl ester of the title compound are obtained.

Quantification of the ester groups was performed using the method described on pages 169-172 by Siggia S. & Hanna J.G. “Quantitative Organic Analysis via Functional Groups” 4th Edition, John Wiley and Sons.

Example 13 Preparation of Hyaluronic Acid β-Phenylethyl Ester

12.4 g of the tetrabutylammonium salt of hyaluronic acid with a molecular weight of 125,000 corresponding to 20 mol of monomer were dissolved in 620 ml of dimethyl sulfoxide at 25 ° C, 4.6 g (25 mol) of 2-bromoethylbenzene and 185 mg of tetrabutylammonium iodide were added and the resulting solution was maintained at 30 ° C for 12 h.

The resulting mixture was slowly poured into 3500 ml of ethyl acetate with continuous stirring. A precipitate formed which was filtered and washed four times with 500 ml of ethyl acetate and finally dried in vacuo for 24 hours at 30 ° C.

9.1 g of the β-phenylethyl ester, the title compound, are obtained.

Quantification of the ester groups was performed using the method described on pages 169-172 by Siggia S. & Hanna J.G. “Quantitative Organic Analysis via Functional Groups” 4th Edition, John Wiley and Sons.

Example 14. Preparation of hyaluronic acid benzyl ester g of hyaluronic acid potassium salt with a molecular weight of 162,000 were suspended in 200 ml of dimethyl sulfoxide, 120 mg of tetrabutylammonium iodide and 2.4 g of benzyl bromide were added.

The suspension was stirred for 48 h at 30 ° C. The resulting mixture was slowly poured into 1000 ml of ethyl acetate with continuous stirring. A precipitate formed which was filtered and washed four times with 150 ml of ethyl acetate and finally dried under vacuum for 30 h at 30 ° C.

3.1 g of the benzyl ester of the title compound are obtained. Quantification of the ester groups was performed using the method described on page 169172 by Siggia S. & Hanna J.G. “Quantitative Organic Analysis via Functional Groups” 4th Edition, John Wiley and Sons.

Example 15. Preparation of (partial propyl) hyaluronic acid ester 85% esterified carboxylic groups 15% salt-converted carboxylic groups

12.4 g of the tetrabutylammonium salt of hyaluronic acid, with a molecular weight of 165,000 corresponding to 20 ml of the monomer, were dissolved in 620 ml of dimethyl sulfoxide at 25 ° C, 2.9 g (17 mol) of propyl iodide was added and the resulting solution was maintained over for 12 h at 30 ° C.

A solution containing 62 ml of water and 9 g of sodium chloride was added and the resulting mixture was slowly poured into 3500 ml of acetone with continuous stirring. A precipitate formed which was filtered and washed three times with 500 ml of acetone / water (5: 1), three times with acetone and finally dried in vacuo for 8 hours at 30 ° C.

The product was then dissolved in 550 ml of water containing 1% sodium chloride and the solution slowly poured into 3000 ml of acetone with continuous stirring. A precipitate formed which was filtered and washed twice with 500 ml of acetone / water (5: 1) and three times with 500 ml of acetone, then finally dried under vacuum for 24 hours at 30 ° C.

8 g of a partial propyl ester, the title compound, are obtained.

Quantification of ester groups was performed using the method of R.H. Cundiff and P.C. Markunas [Anal. Chem. 33, 1028-1030 (1961)].

Example 16 Preparation of Hyaluronic Acid p-Octyl Ester

12.4 g of the tetrabutylammonium salt of hyaluronic acid, with a molecular weight of 170,000 corresponding to 20 mol of monomer, were dissolved in 620 ml of dimethyl sulfoxide at 25 ° C, 4.1 g (21.2 mol) of 1-bromoctane were added and the resulting solution maintained at 30 ° C for 12 h.

The resulting mixture was slowly poured into 3500 ml of ethyl acetate with continuous stirring. A precipitate formed which was filtered and washed four times with 500 ml of ethyl acetate and finally dried under vacuum for 30 h at 30 ° C. 9.3 g of the octyl ester, the title compound, are obtained.

Quantification of the ester groups was performed using the method described on pages 169-172 by Siggia S. & Hanna J.G. “Quantitative Organic Analysis via Functional Groups” 4th Edition, John Wiley and Sons.

Example 17. Preparation of hyaluronic acid isopropyl ester

12.4 g of the tetrabutylammonium salt of hyaluronic acid with a molecular weight of 170,000 corresponding to 20 mol of monomer were dissolved in 620 ml of dimethyl sulfoxide at 25 ° C, 2.6 g (21.2 mol) of isopropyl bromide were added and the resulting solution was maintained for 12 h at 30 ° C.

The resulting mixture was slowly poured into 3500 ml of ethyl acetate with continuous stirring. A precipitate formed which was filtered and washed four times with 500 ml of ethyl acetate and finally dried in vacuo for 24 hours at 30 ° C. 8.3 g of the isopropyl ester of the title compound are obtained.

Quantification of ester groups was performed using the method of R.H. Cundiff and P.C. Markunas [Anal. Chem. 33, 1028-1030 (1961)].

Example 18. Preparation of 2,6-dichlorobenzyl ester of hyaluronic acid

12.4 g of the tetrabutylammonium salt of hyaluronic acid with a molecular weight of 170,000 corresponding to 20 mol of monomer were dissolved in 620 ml of dimethyl sulfoxide at 25 ° C, 5.08 g (21.2 mol) of 2,6-dichlorobenzyl bromide were added and the resulting solution was maintained at 30 ° C for 12 h.

The resulting mixture was slowly poured into 3500 ml of ethyl acetate with continuous stirring. A precipitate formed which was filtered and washed four times with 500 ml of ethyl acetate and finally dried in vacuo for 24 hours at 30 ° C. 9.8 g of the 2,6-dichlorobenzyl ester, the title compound, are obtained.

Quantification of the ester groups was performed using the method described on pages 169-172 by Siggia S. & Hanna J.G. “Quantitative Organic Analysis via Functional Groups” 4th Edition, John Wiley and Sons.

Example 19. Preparation of 4-tert-butylbenzyl ester of hyaluronic acid

12.4 g of the tetrabutylammonium salt of hyaluronic acid, with a molecular weight of 170,000 corresponding to 20 mol of monomer, were dissolved in 620 ml of dimethyl sulfoxide at 25 ° C, 4.81 g (21.2 mol) of 4-tert-butylbenzyl bromide were added and the resulting solution was maintained at 30 ° C for 12 h.

The resulting mixture was slowly poured into 3500 ml of ethyl acetate with continuous stirring. A precipitate formed which was filtered and washed four times with 500 ml of ethyl acetate and finally dried in vacuo for 24 hours at 30 ° C. 9.8 g of the 4-tert-butylbenzyl ester, the title compound, are obtained.

Quantification of the ester groups was performed using the method described on pages 169-172 by Siggia S. & Hanna J.G. “Quantitative Organic Analysis via Functional Groups” 4th Edition, John Wiley and Sons.

Example 20. Preparation of Hyaluronic Acid Heptadecyl Ester

12.4 g of the tetrabutylammonium salt of hyaluronic acid with a molecular weight of 170,000 corresponding to 20 mol of the monomer were dissolved in 620 ml of dimethyl sulfoxide at 25 ° C, 6.8 g (21.2 mol) of heptadecyl bromide were added and the resulting solution was maintained for 12 h at 30 ° C.

The resulting mixture was slowly poured into 3500 ml of ethyl acetate with continuous stirring. A precipitate formed which was filtered and washed four times with 500 ml of ethyl acetate and finally dried in vacuo for 24 hours at 30 ° C. 11 g of the title heptadecyl ester are obtained.

Quantification of the ester groups was performed using the method described on pages 169-172 by Siggia S. & Hanna J.G. “Quantitative Organic Analysis via Functional Groups” 4th Edition, John Wiley and Sons.

Example 21. Preparation of octadecyl ester of hyaluronic acid

12.4 g of the tetrabutylammonium salt of hyaluronic acid, with a molecular weight of 170,000 corresponding to 20 mol of monomer, were dissolved in 620 ml of dimethyl sulfoxide at 25 ° C, 7.1 g (21.2 mol) of octadecyl bromide were added and the resulting solution was maintained for 12 h at 30 ° C.

The resulting mixture was slowly poured into 3500 ml of ethyl acetate with continuous stirring. A precipitate formed which was filtered and washed four times with 500 ml of ethyl acetate and finally dried in vacuo for 24 hours at 30 ° C. 11 g of the octadecyl ester, the title compound, are obtained.

Quantification of the ester groups was performed using the method described on pages 169-172 by Siggia S. & Hanna J.G. “Quantitative Organic Analysis via Functional Groups” 4th Edition, John Wiley and Sons.

Example 22. Preparation of 3-phenylpropyl ester of hyaluronic acid

12.4 g of the tetrabutylammonium salt of hyaluronic acid with a molecular weight of 170,000 corresponding to 20 mol of monomer were dissolved in 620 ml of dimethyl sulfoxide at 25 ° C, 4.22 g (21.2 mol) of 3-phenylpropyl bromide were added and the resulting solution maintained at 30 ° C for 12 h.

The resulting mixture was slowly poured into 3500 ml of ethyl acetate with continuous stirring. A precipitate formed which was filtered and washed four times with 500 ml of ethyl acetate and finally dried in vacuo for 24 hours at 30 ° C. 9 g of the 3-phenylpropyl ester, the title compound, are obtained.

Quantification of the ester groups was performed using the method described on pages 169-172 by Siggia S. & Hanna J.G. “Quantitative Organic Analysis via Functional Groups” 4th Edition, John Wiley and Sons.

Example 23. Preparation of 3,4,5-trimethoxy-benzyl ester of hyaluronic acid

12.4 g of the tetrabutylammonium salt of hyaluronic acid with a molecular weight of 170,000 corresponding to 20 mol of monomer were dissolved in 620 ml of dimethyl sulfoxide at 25 ° C, 4.6 g (21.2 mol) of 3,4,5- trimethoxy-benzyl chloride and the resulting solution was maintained at 30 ° C for 12 h.

The resulting mixture was slowly poured into 3500 ml of ethyl acetate with continuous stirring. A precipitate formed which was filtered and washed four times with 500 ml of ethyl acetate and finally dried under vacuum for 24 hours at 30 ° C. 10 g of 3,4,5-trimethoxybenzyl ester - the title compound are obtained.

Quantification of the ester groups was performed using the method described on pages 169-172 by Siggia S. & Hanna J.G. “Quantitative Organic Analysis via Functional Groups” 4th Edition, John Wiley and Sons.

Example 24. Preparation of cinnamyl ester of hyaluronic acid

12.4 g of the tetrabutylammonium salt of hyaluronic acid with a molecular weight of 170,000 corresponding to 20 mol of the monomer were dissolved in 620 ml of dimethyl sulfoxide at 25 ° C, 4.2 g (21.2 mol) of cinnamyl bromide were added and the resulting solution was maintained for 12 h at 30 ° C.

The resulting mixture was slowly poured into 3500 ml of ethyl acetate with continuous stirring. A precipitate formed which was filtered and washed four times with 500 ml of ethyl acetate and finally dried in vacuo for 24 hours at 30 ° C. 9.3 g of the cinnamyl ester, the title compound, are obtained.

Quantification of the ester groups was performed using the method described on pages 169-172 by Siggia S. & Hanna J.G. “Quantitative Organic Analysis via Functional Groups” 4th Edition, John Wiley and Sons.

Example 25. Preparation of hyaluronic acid decyl ester

12.4 g of the tetrabutylammonium salt of hyaluronic acid, with a molecular weight of 170,000 corresponding to 20 mol of monomer, were dissolved in 620 ml of dimethyl sulfoxide at 25 ° C, 4.7 g (21.2 mol) of 1-bromodecane were added and the resulting solution maintained at 30 ° C for 12 h.

The resulting mixture was slowly poured into 3500 ml of ethyl acetate with continuous stirring. A precipitate formed which was filtered and washed four times with 500 ml of ethyl acetate and finally dried in vacuo for 24 hours at 30 ° C. 9.5 g of the decyl ester of the title compound are obtained.

Quantification of the ester groups was performed using the method described on pages 169-172 by Siggia S. & Hanna J.G. “Quantitative Organic Analysis via Functional Groups” 4th Edition, John Wiley and Sons.

EXAMPLE 26 Preparation of Hyaluronic Acid Nonyl Ester

12.4 g of the tetrabutylammonium salt of hyaluronic acid with a molecular weight of 170,000 corresponding to 20 mol of the monomer were dissolved in 620 ml of dimethyl sulfoxide at 25 ° C, 4.4 g (21.2 mol) of 1-bromonanone were added and the resultant the solution was maintained at 30 ° C for 12 h.

The resulting mixture was slowly poured into 3500 ml of ethyl acetate with continuous stirring. A precipitate formed which was filtered and washed four times with 500 ml of ethyl acetate and finally dried in vacuo for 24 hours at 30 ° C. 9 g of the nonyl ester title compound are obtained.

Quantification of the ester groups was performed using the method described on pages 169-172 by Siggia S. & Hanna J.G. “Quantitative Organic Analysis via Functional Groups” 4th Edition, John Wiley and Sons.

Alginic acid esters

The alginic acid esters that can be used in the invention can be prepared by the method described in EPA 0 251 905 A2, starting from the quaternary ammonium salts of the alginic acid with an esterifying agent, preferably in an aprotic organic solvent, such as dialkylsulfoxides, dialkylcarboxamides, particularly preferred are lower alkyl dialkyl sulfoxides, in particular dimethyl sulfoxide and lower alkyl dialkyl amides with lower aliphatic acids, such as dimethyl or diethylformamide, or dimethylacetamide. However, other solvents that are not always aprotic, such as alcohols, ethers, ketones, esters, especially aliphatic or heterocyclic alcohols and low boiling point ketones, such as hexafluoroisopropanol and trifluoroethanol, may also be used. The reaction is preferably carried out at temperatures between about 0 and 100 ° C, in particular between about 25 and 75 ° C, for example about 30 ° C.

Preferably, the esterification is carried out by the gradual addition of an esterifying agent to the aforementioned ammonium salt dissolved in one of said solvents, for example dimethyl sulfoxide. The alkylating agents already mentioned above, in particular hydrocarbyl halides, for example alkyl halides, may be used as alkylating agents.

The preferred esterification process therefore involves reacting in an organic solvent a quaternary ammonium salt of alginic acid with a stoichiometric amount of a compound of the general formula

A - X in which A is selected from the group consisting of aliphatic, arylaliphatic, cycloaliphatic, aliphatic-cycloaliphatic and heterocyclic radicals, and X represents a halogen atom, and in which the stoichiometric amount of A-X is determined by the desired degree of esterification .

As starting quaternary ammonium salts, it is advisable to use lower alkyl tetraalkylates, the alkyl groups of which preferably have from 1 to 6 carbon atoms. Tetrabutylammonium alginate is most commonly used. These quaternary ammonium salts can be obtained by reacting a metal salt of alginic acid, preferably one of those mentioned above, in particular the sodium or potassium salt, in aqueous solution with the salt quaternary ammonium base converted to salt.

A variant of the procedure described above consists of reacting a potassium or sodium salt of alginic acid dissolved or suspended in a suitable solvent, such as dimethyl sulfoxide, with a suitable alkylating agent in the presence of a catalytically acting amount of quaternary ammonium salt, for example tetrabutide. This procedure makes it possible to obtain total alginic acid esters.

For the preparation of new esters it is possible to use alginic acids of any origin. The preparation of these acids has been described in the literature. Preferably, purified alginic acids are used.

In the partial esters, it is possible to convert to the salt all carboxylic groups or only part of them, the amount of base being dosed to obtain the desired stoichiometric degree of conversion to salt. With proper dosage the degree of conversion to salt, esters with a wide range of different dissociation constants can be obtained, thereby creating the desired pH of the in situ solutions for therapeutic use.

Particularly useful for the presented multilayer membranes are ALAFF 11, alginic acid benzyl ester and ALAFF 7, alginic acid ethyl ester.

Example 27. Non-woven material containing hyaluronic acid benzyl ester - HYAFF 11, weighing 40 g / m ² , with thickness

0.5 mm was manufactured according to the procedure described below (see Figure 1).

A solution of HYAFF 11 in dimethyl sulfoxide at a concentration of 135 g / ml was prepared in tank 1 and fed through a dental metering pump 2 into a wet extrusion filler consisting of 3000 openings, each 65 mm in diameter.

The extruded fiber mass is passed into a coagulation bath 3 containing absolute ethanol and then transported by rollers to two successive rinsing baths 4 and 5 containing absolute ethanol. The draw ratio of the first rolls is 1, while the draw ratio between the other rolls is set to 1.05. After passing through the rinsing baths once, the yarn branch is dried by purging with hot air at a temperature of 45-50 ° C 6 and cut with a roller knife 7 on fibers of 40 mm length.

The fiber mass thus obtained is poured into a chute leading to a carding / cross-folding machine, from which it emerges in the form of felt, 1 mm thick and weighing 40 g / m ² . This material is then sprayed with a solution of HYAFF 11 in dimethyl sulfoxide at a concentration of 80 mg / mill, placed in an ethanol coagulation bath 12, in a rinsing chamber 13 and finally in a drying chamber 14.

The final thickness of the material is 0.5 mm. Its appearance can be seen in Figure 2.

Example 28. Non-woven material containing hyaluronic acid ethyl ester, HYAFF 7, weighing 200 g / m ² and 1.5 mm thick, was prepared according to the following procedure.

HYAFF 7 fibers of 3 mm length, obtained by the drawing process described in Example 27, are fed through the groove into the carding machine, from which they emerge in the form of material 1.8 mm thick and weighing 200 g / m ² . This material is passed through a needle puncture machine (Fig. 1, items 16, 17 and 18), which converts them into a non-woven material weighing 200 g / m ² and 1.5 mm thick.

Example 29. A non-woven material weighing 200 g / m ² and 1.5 mm thick containing a mixture of hyaluronic acid ethyl ester, HYAFF 7 and hyaluronic acid benzyl ester, HYAFF 11 was obtained in equal quantities according to the following procedure.

Fibers of HYAFF 7 and HYAFF lie 3 mm long, obtained by the method described in Example 27, were mixed in a spiral mixer. The fiber mixture is fed into a carding machine, from which they appear in the form of felt 1.8 mm thick and weighing 200 g / m ² .

This material is passed through a needle puncture machine (Fig. 1, poses 16, 17 and 18), which converts it into a non-woven material 1.5 mm thick, weighing 200 g / m ² , with the two materials perfectly mixed with one another. another.

Example 30. A non-woven material weighing 40 g / m ² and a thickness of 0.5 mm containing a mixture of hyaluronic acid benzyl ester, HYAFF 11 and partial (75%) hyaluronic acid benzyl ester, HYAFF 11p75 in equal percentages, was obtained according to the following procedure.

HYAFF 11p75 was prepared as follows. 10 g of tetrabutylammonium salt of hyaluronic acid with molecular weight = 620.76 equal to 16.1 nmol are dissolved in a mixture of N-methylpyrrolidone / water, 90/10, 2.5% by weight, preferably in 400 ml of solution. . The solution was cooled to 10 ° C, then purified nitrogen was bubbled through it for 30 min. The mixture was then esterified with 1.49 ml (equal to 12.54 mmol) of benzyl bromide. The solution was shaken gently for 60 h at 15-20 ° C.

Further purification is achieved by precipitation in ethyl acetate, followed by the addition of saturated sodium chloride solution and subsequent washing with ethyl acetate / absolute ethanol 80/20. The solid was filtered off and treated with anhydrous acetone. In this way 6.8 g of product are obtained, equal to a yield of about 95%.

Fibers of HYAFF 11 and HYAFF 11p75 40 mm in length, obtained by the method described in Example 1, are completely mixed in a spiral mixer.

The mixed fibers are fed into a carding machine, from which they emerge in the form of tissue 1 mm thick and weighing 40 mg / m ² . The tissue was then sprayed with a solution of HYAFF 11 in dimethyl sulfoxide at a concentration of 80 mg / ml (Figure 1, item 11), placed in an ethanol coagulation bath 12, then in a rinse chamber 13 containing water or a mixture of water and ethanol in a ratio of 10 to 95% ethanol, and finally in the drying chamber 14.

The material is 0.5 mm thick and the fibers of HYAFF 11 and HYAFF 11p75 are perfectly mixed and bonded together.

Example 31. A non-woven material containing hyaluronic acid benzyl ester, HYAFF 11, weighing 200 g / m ² and vancomycin impregnated 1.5 mm thick, was prepared according to the following procedure.

The non-woven material obtained by the method described in Example 28 was soaked for 4 hours in an aqueous solution of vancomycin at a concentration of 0.1 mg / ml. Then, after treatment in the heated strainer, the non-woven material is dried for 2 hours in an oven. In vitro tests have shown that vancomycin is contained in the material in pharmacologically active amounts.

The non-woven material of the invention can be used with success in various types of microsurgical procedures, such as in dentistry, dentistry, otorhinolaryngology, orthopedics, neurosurgery, etc., in which it is necessary to use a substance that can be metabolized by the body and which can facilitate skin formation on the wound, re-epithelialization of the mucous membranes, stabilization of implants and filling of cavities. New nonwovens can also be used as a buffer medium in nose and inner ear surgery.

It is clear from the description of the utility model that it can be implemented in different variants. These variants are not to be considered as being beyond the scope of the invention, and any such modifications, as will be noted immediately by one of ordinary skill in the art, are within the scope of the claims.

Claims

Claims (20)

1. Non-woven material for use in the treatment of skin diseases and directed tissue regeneration in surgery, dermatology, orthodontics, dentistry, orthopedics, neurosurgery or otorhinolaryngology, characterized in that it contains fibers of at least one ester of hyaluronic acid or fibers of hyaluronic acid ester in combination with another polymer. 2. A non-woven material according to claim 1, wherein said hyaluronic acid derivative is at least one hyaluronic acid ester. Non-woven material according to claim 1, characterized in that said polymer is at least one member selected from the group consisting of collagen, co-collagen and glucosaminoglycan, cellulose, a polysaccharide in the form of a gel, a semi-synthetic polymer derivative and synthetic polymer. Non-woven fabric according to claim 3, characterized in that said polysaccharide in the form of a gel is a member selected from the group consisting of chitin, cytosine, pectin, pectic acid, agar, agarose, xanthan gum, gel, alginic acid, alginate, polymanan, polyglycan, starch and natural resin. 5. Non-woven material according to claim 3, characterized in that said semisynthetic polymer derivative is a member selected from the group consisting of chemically cross-linked collagen, cellulose derivative, alginic acid derivative, starch derivative, chitin derivative of cytosan, gellan derivative, xanthan derivative, pectin derivative, pectic acid derivative, polyglycan derivative, polyamine derivative, agar derivative, agarose derivative, natural resin derivative and derivative of glucosaminoglycan. Non-woven material according to claim 3, characterized in that the non-woven polymer is a member selected from the group consisting of polylactic acid, polyglycolic acid, a copolymer of polylactic and polyglycolic acid, a copolymer of a polylactic acid derivative and a polyglycolic acid derivative , polydioxane, polyphosphazene, polysulfone resin and polyurethane resin. Non-woven material according to claim 2, characterized in that said hyaluronic acid ester is present alone or in combination with other hyaluronic acid esters. Non-woven material according to claim 2, characterized in that the hyaluronic acid ester is a hyaluronic acid ethyl ester. 9. A nonwoven fabric according to claim 2, wherein the hyaluronic acid ester is a hyaluronic acid benzyl ester. Non-woven material according to claim 5, characterized in that the non-woven material comprises a mixture of hyaluronic acid ethyl ester and hyaluronic acid benzyl ester. Non-woven material according to claim 2, characterized in that the non-woven material comprises a mixture of hyaluronic acid benzyl ester and hyaluronic acid partial benzyl ester. 12. Non-woven material according to claim 11, characterized in that the partial benzyl ester of hyaluronic acid is 75% benzyl ester. 13. The non-woven material of claim 1, wherein the non-woven material is impregnated with a pharmacologically active antibiotic solution. 14. A non-woven fabric according to claim 13, wherein said antibiotic is vancomycin. 15. Non-woven fabric according to claim 1, characterized in that it weighs between about 20 and about 500 g / m, has a thickness between about 0.2 and 5 mm, a fiber diameter between about 12 and about 60 μ, and a length of fibers between about 5 and about 100 mm. Non-woven fabric according to claim 1, characterized in that it weighs about 40 g / m, has a thickness of about 0.5 mm, a diameter of fibers of about 20 pm and a length of fibers of about 40 mm. Non-woven fabric according to claim 1, characterized in that it weighs about 200 g / m, has a thickness of about 1.5 mm, a diameter of fibers of about 2 pm and a length of fibers of about 3 mm. 18. The non-woven material of claim 1, wherein the hyaluronic acid ester is formed by esterifying the hyaluronic acid with an alcohol that is pharmacologically inert. 19. The non-woven material according to claim 2, wherein the alcohol of said ester is a pharmacologically inactive alcohol. 20. The non-woven material of claim 1, wherein the hyaluronic acid ester is formed by esterifying the hyaluronic acid with an alcohol that is pharmacologically active.