JP3202790B2 - Novel chitosan derivatives and their uses - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel chitosan derivative and a humectant as a preferred use thereof, and more particularly, to a chitosan derivative which can be arbitrarily dissolved without requiring an acid or alkali, and The present invention relates to a humectant containing a novel chitosan derivative that stably dissolves in a wide pH range.

[0002]

2. Description of the Related Art Cosmetics, pharmaceuticals or lotions,
Various highly hygroscopic substances have been used as humectants for the purpose of imparting moisture retention to products such as creams and ointments. As described above, there are considerable types of substances having high moisture absorption ability, which are important physical properties that can be used as a humectant, including organic substances and inorganic substances. However, when these substances are actually used, they must be excellent in safety, have a low effect on the form stability of the product, have no restrictions on the amount and use of the product, or have a feeling of use. In consideration of not hindering the performance of, it is used as a humectant.

[0003] Commonly used humectants include organic acid salts such as sodium lactate and sodium pyrrolidone carboxylate; polyhydric alcohols such as glycerin, sorbitol and propylene glycol; and hyaluronic acid, chitin / chitosan and polyacrylic acid. It is a natural or synthetic water-soluble polymer. These are used singly or in combination, but each has advantages and disadvantages in terms of effects on product stability, solubility, feeling of use such as stickiness, price, and the like, and their uses were naturally limited.

[0004] In recent years, various attempts have been made to use chitin and chitosan as moisturizers, focusing on the hygroscopicity and good feeling of use of inexpensive natural polymers and abundant resources. For example, Japanese Patent Application Laid-Open No.
-19040, JP-A-54-95740,
JP-A-59-106409, JP-A-60-111
No. 0 or JP-A-2-105801. However, chitin / chitosan or a derivative thereof disclosed in these prior arts has insufficient solubility or impairs the excellent feeling of use of chitin / chitosan. There are many restrictions.

For example, N-acylated chitosan, chitosan and water-soluble partially deacetylated chitin disclosed in JP-A-49-19040, JP-A-54-95740 and JP-A-60-1110 are disclosed. It is used in cosmetics and other products after solubilization using organic or inorganic acids.However, these chitosans have disadvantages in that the pH range of the products is limited by the relationship with the acid used, and There is a problem that its solubility is not stable in a wide pH range.

On the other hand, humectants used in cosmetics and pharmaceuticals are desired to be soluble under any conditions in a wide range of pH from 3.5 to 10. The chitin / chitosan derivatives disclosed in JP-A-59-106409 and JP-A-2-105801 dissolve stably in a wide pH range of 3.5 to 10 with respect to solubility. The derivatization impairs the excellent feeling of use of chitin / chitosan, and when added to a product, causes a sticky or tight feeling, impairs the performance of the product in terms of feeling of use, and naturally limits the amount of compounding.

[0007]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to stably dissolve chitin and chitosan in a wide pH range without impairing the hygroscopicity and excellent feeling of use of the chitin. In particular, it is to provide a novel chitosan derivative suitably used as a humectant.

[0008]

DISCLOSURE OF THE INVENTION The present invention has been proposed to achieve the above object, and has a feature in that a chitosan derivative having a specific structure has been found. That is, according to the present invention, the following formulas (a), (b) and (c) are irregularly distributed in the molecule, and the ratio of the three constituent units is (a) N-acetyl-D-glucosamine constituent unit; 32 to 65% (b) D-glucosamine constituent unit; 32 to 65% (c) D-glucosamine modified constituent unit; 3 to 18%

Embedded image

Embedded image

Embedded image A novel chitosan derivative is provided. Here, R in the above formula is any of formulas (1) to (5). (Four)

Embedded image (Five)

Embedded image(However, R₁ Represents a hydrogen atom or a methyl residue;
= 0 or n = 0,
Or R which is different_Two , R_Three , R_Four And R _Five , R
₆ , R₇ Represents a hydrogen atom, a methyl residue,
Residue, acetoxy residue, or acetylthio residue,
Also, R_Two , R_Three Or R_Five , R₆ Together
To form a methylene group, or m = 1, or n = 1
If R_Two , R_Three , R_Four Or R_Five , R₆ , R
₇ Each represents a hydrogen atom. )

[0009]

DETAILED DESCRIPTION OF THE INVENTION The novel chitosan derivative of the present invention
(A) N-acetyl-D-glucosamine constituent unit; 32 to 65%; (b) D-glucosamine constituent unit; 32 to 65%; (c) D-glucosamine modified constituent unit; An important technical feature is that it consists of three components, and the sequence of each structural unit in the molecule is arbitrary. (A) is large in the ratio of the three constituent units,
When (b) is small, it cannot be dissolved in a wide pH range,
When the amount of (a) is small and the amount of (b) is large, it dissolves, but the usability is impaired, and the stability in a solution state is poor, so that it cannot be used. Furthermore, when (a) is small and (b) is large, a wide range of pH
Can not be dissolved in the area. In addition, even if (c) is more than 18%, 3
% Cannot be dissolved in a wide range of pH. In view of these circumstances, as a result of various examination of the composition ratio,
Chitosan derivative comprising (a) N-acetyl-D-glucosamine constituent unit; 32 to 65%, (b) D-glucosamine constituent unit; 32 to 65%, (c) D-glucosamine modified constituent unit; 3 to 18% However, the present inventors have found that they satisfy all the desired physical properties as a humectant, and have completed the present invention.

[0010] The novel chitosan derivative in the present invention is a chitosan derivative which can be easily produced from natural chitin or chitosan obtained by deacetylating chitin without using any special equipment or process. That is, the compound is acylated using a saturated or unsaturated acid anhydride, and in the case of an unsaturated acid anhydride, a carboxyl group, a sulfonic acid group, a sulfate group, or the like, which further enhances solubility, is obtained by adding to a double bond. And a novel chitosan derivative, characterized by the aforementioned three structural units (a), (b) and (c).

The acylation reaction of chitosan is carried out by adding 0.2 to 10% of an aqueous solution of a salt of chitosan to D-
This is performed by adding the compound introduced to the glucosamine structural unit and stirring the mixture. The reaction is preferably performed in a homogeneous solution state, and when adjusting the pH of the reaction solution during the reaction,
Preferably, no insolubles are produced. Further, the reaction temperature affects the viscosity of the reaction solution and the acylation reaction rate. When the viscosity of the chitosan solution is high, the reaction at a high temperature is preferable in order to enhance the uniformity of the reaction solution. In the production at a high temperature, the acylation reaction is advantageous for the reaction with chitosan, and therefore the amount of the compound added to the D-glucosamine structural unit may be smaller than that at the low temperature.

The reaction conditions such as the amount of the chitosan added to the compound introduced into the D-glucosamine structural unit differ depending on the physical properties such as the degree of deacetylation and the viscosity of the chitosan. For chitosan with a degree of deacetylation of 85% (viscosity of a 0.5% solution 200 cps), the D-glucosamine building block 1 present in chitosan 1
5 to 15 equivalents of acetylating agent is added per equivalent,
After stirring for about 2 hours, the acid anhydride is further worked up using 3.5 to 6.5 equivalents per equivalent of D-glucosamine building block present in the chitosan. In this reaction, the acid anhydride and the acetylating agent can be used in the form of a powder or dispersed and dissolved in an inert solvent such as dioxane, tetrahydrofuran or ethyl acetate.

Since the product of the present invention is already stably dissolved in a wide pH range at the end of production, a method of isolating a precipitate from an aqueous solution by adding a solvent such as alcohol or acetone can be used.

The acidic and basic groups represented in the molecules of the polymers according to the invention can be ionized in aqueous solution, between the structural units B and C or within the same structural unit C. To give salt. These ionized forms also appear in the presence of inorganic or organic acids and bases. Salts formed with these acids or bases also form part of the invention.

These salts include, for example, acids such as hydrochloric acid, phosphoric acid, acetic acid, lactic acid, tartaric acid or citric acid or sodium hydroxide, potassium hydroxide, ammonia, lime magnesia, alkanolamines such as triethanolamine, triisopropanolamine, amino It can be obtained with a base such as methylpropanol or aminomethylpropanediol or more specifically with an amino acid having a basic character such as lysine or arginine.

The compound of the present invention has the following formula (11)
(15)

Embedded image (Where R ₁ represents a hydrogen atom or a methyl residue;
= 0 or n = 0, the same or different R ₂ , R ₃ , R ₄ and R ₅ , R
₆ and R ₇ are each a hydrogen atom, a methyl residue, a hydroxyl residue, an acetoxy residue, or an acetylthio residue;
Further, the groups R ₂ and R ₃ or the groups R ₅ and R ₆ together form a methylene group, or m = 1 or n = 1
, R ₂ , R ₃ , R ₄ or R ₅ , R ₆ , R
₇ represents a hydrogen atom. By acylating a chitosan with a saturated or unsaturated acid anhydride), prepared according to the process was completed by the applicant.

The salt of chitosan used in the acylation reaction can be, for example, chlorohydrate or sodium hydrate, as long as the base can be sodium or potassium hydroxide or, more preferably, an acidic or neutral carbonate of sodium or potassium. It may be acetate, hydrochloride, lactate.

The saturated acid anhydride used is, for example, succinic anhydride, acetoxysuccinic anhydride, methylsuccinic anhydride,
It may be diacetyltartaric anhydride or diglycolic anhydride. The unsaturated acid anhydride used may be, for example, maleic anhydride, itaconic anhydride, tartaric anhydride. If the starting acid anhydride is unsaturated, the acylation reaction can be followed by an addition reaction, thereby making the product very broad.

The novel chitosan derivative in the present invention is selected from those which do not impair the solubility and pH stability in water and the feeling of use of chitosan, thereby enabling the use as a humectant which is the object of the present invention. . The humectant of the present invention exhibits excellent moisture absorption and retention properties as shown in Examples described later, and has solubility and pH stability in water that cannot be achieved by conventional chitosan and chitosan derivatives, and has no stickiness and no feeling of tightness. It was able to satisfy excellent usability at the same time. The humectant of the present invention is a highly safe substance like chitosan, and also has a film-forming ability derived from a polymer structure, an antistatic effect, and the like.

Therefore, the humectant of the present invention can be used not only in foods, cosmetics, medicines, daily necessities such as shoe creams, but also in paints, bath additives, toothpastes, paper products, etc. for the purpose of suppressing water loss. In addition, it can be used for antistatic effect, improvement in feeling of use of the product or feeling after use, or thickening effect. Further, the humectant of the present invention can be used irrespective of the form of a cream, lotion, gel, aqueous solution, or oil or aerosol product due to its excellent solubility in water and pH stability.

Furthermore, the effect of the humectant of the present invention is not impaired even when used in combination with other known humectants such as glycerin, propylene glycol, sorbitol, sodium pyrrolidonecarboxylate, sodium lactate and amino acids. Furthermore, various surfactants, solubilizers,
It can also be used in combination with oils and the like.

When the humectant of the present invention is blended with various products, it does not affect the physical properties of the target product due to its excellent solubility in water, pH stability and feeling of use. Can be arbitrarily added in accordance with the characteristics, viscosity and intended use of the compound, but the desired purpose can be achieved by adding 0.01 to 20% by weight.

[0023]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

<Production Example 1> (Production of chitosan condensation product with succinic anhydride) Water 5
Chitosan dispersed in 00 g (degree of deacetylation 85%)
To 2.5 g, 1.8 g of concentrated hydrochloric acid is added to neutralize the free D-glucosamine structural unit and completely dissolved. Filtered to separate insoluble chitosan particles. Next, 5 g of acetic anhydride was added and the mixture was stirred for 1 hour. Subsequently, 15 g of succinic anhydride was added and the mixture was further stirred for 2 hours. When the reaction was completed, the pH of the reaction solution was adjusted to 10 to precipitate a precipitate with ethanol. The precipitate was washed with 50% ethanol and then with acetone, and dried to obtain a sodium salt of a novel chitosan derivative.

The amount of the functional group to be introduced can be determined by colloid titration, which is a known method. Therefore, a new degree of acetylation is determined before the addition of succinic anhydride,
The degree of succinylation is determined from the final product. It shows that the degree of acetylation is 49.5% from the colloid titration of 5 mg of dry sample with N / 400 potassium polyvinylsulfate of 5.42 ml and the degree of succinylation is also 13.1 from the colloid titration of 3.70 ml. %. Therefore, the amount of glucosamine constituent units was 37.4%.

<Production Example 2> (Production of chitosan condensation product with maleic anhydride) Chitosan dispersed in 500 g of water (degree of deacetylation: 70)
%) 2.5 g of concentrated hydrochloric acid to neutralize the free D-glucosamine structural unit was added to 2.5 g, and completely dissolved. Filtered to separate insoluble chitosan particles. Next, 0.5 g of maleic anhydride was added, and the mixture was stirred for 2 hours. At this point, the pH of the reaction solution was adjusted to 5.0, and then the acetic anhydride was added.
2 g was added, and the mixture was further stirred for 2 hours. When the reaction was completed, the pH of the reaction solution was adjusted to 10 to precipitate a precipitate with ethanol. The precipitate was washed with 50% ethanol and then with acetone, and dried to obtain a sodium salt of a novel chitosan derivative.

The amount of the functional group to be introduced can be determined by colloid titration, which is a known method similar to that of Production Example 1. As a result of the measurement, the ratio of the three constituent units was (a) 50%, (b) 45
%, (C) 5%. Other compounds summarized in Table 1 below were prepared in the same manner as in Preparation Example 1 or 2.

<Production Example 3> (Production of a compound obtained by adding a sulfonic acid group to the compound prepared in Production Example 2) In 500 g of water, 2.5 g of the compound of Production Example 2 is dissolved. 5 g of sodium bisulfite (NaHSO ₃ ) is added to the homogeneous solution, and the mixture is stirred at room temperature for 2 hours. Then, the pH of the reaction solution was adjusted to 10 with sodium hydroxide, and a precipitate was precipitated with ethanol to obtain the desired compound. Further, the compound thus obtained was precipitated with acetone. The same procedure was followed to make other compounds summarized in Table 2 below.

[0029]

[0030]

<Test Example 1> (Solubility test) Test method Samples used in the solubility test (Examples 1 to 8 and Comparative Examples 1 to 5 shown in Table 3) were made to a final concentration of 0.5%.
Alternatively, it was dissolved in purified water to 1%. Samples that could not be dissolved in purified water were dissolved using a known amount of sodium hydroxide or emulsion. Next, the solubility of the sample in the acidic region was examined using lactic acid, and the solubility in the alkaline region was examined using sodium hydroxide, and the solubility at each pH was confirmed. The solubility evaluation criteria are shown below.

Solubility in purified water Dissolves easily 2. Hard to dissolve 3. 3. Dissolution by addition of acid or alkali Not soluble Solubility in a wide pH range a. Stable dissolution at pH 3.5 to 10 b. Poor solubility in acidic region c. Poor solubility in alkaline region d. Poor solubility in acidic or alkaline region

[0033]

[0034] Test results From the results of the solubility of the products 1 to 8 of the present invention and Comparative Examples 1 to 7, the constitutional units (a), (b) and (c) of the product of the present invention were found to have a specific range defined in the claims Use acid and alkali
It is clear that the solubility is excellent without
It is understood that the solubility is reduced outside this range.

<Test Example 2> (Moisture retention test) Test method High frequency impedance meter (manufactured by IBS: MODEL I)
B-355) using purified water as a control.
The moisture retention of a 5% chitosan derivative solution (Production Example 1) was examined. For comparison with other polysaccharides, a highly moisturizing sodium hyaluronate and a 0.5% solution of chitosan were similarly examined as a control.

Measurement method A sample was applied (2 cm × 2 cm) inside the human forearm,
After 30 seconds, the skin was quickly wiped lightly with gauze, and the conductance of the skin was measured every 30 seconds up to 10 minutes. (Measurement conditions: measurement room temperature 20 ° C, humidity 60%, number of measurements n = 10)

Test Results The results are shown in FIG. The results in FIG. 1 show that the higher the conductivity, the higher the moisturizing property. The chitosan derivative of the present invention is equal to or better than sodium hyaluronate and chitosan, which are said to have excellent moisturizing properties. Humectant was confirmed to be excellent as a humectant.

<Test Example 3> (Usability Evaluation Test) Test Method Conventional polysaccharides (chitosan, carboxymethyl chitin, sodium hyaluronate) were tested using a lotion (formulation example 3 described below) using the chitosan derivative of the present invention. ) Was compared by a sensory test.

The feeling of use was evaluated by panelists who randomly divided 50 healthy women into 5 groups of 10 each. In the first group, the lotion of the prescription example 3 (the present invention) was added to the second group.
The group was a lotion containing only the chitosan derivative of Formulation Example 3 instead of chitosan (Comparative Example 1), and the third group was a lotion containing only the chitosan derivative of Formulation Example 3 instead of sodium hyaluronate (Comparative Example 2). In the fourth group, a lotion excluding the chitosan derivative of Formulation Example 3 was replaced by carboxymethyl chitin (Comparative Example 3), and in the fifth group, a lotion excluding the chitosan derivative of Formulation Example 3 (base: Comparative Example 4) was used.

The five groups of panelists were asked to apply a lotion twice a day, morning and night, after washing their face, and then to apply an appropriate amount to their face for one month. They evaluated the effectiveness of the lotion at the time of use as well as the “skin familiarity (smoothness, firmness, stickiness)”. The evaluation of "moistness of the skin" was evaluated in four steps of "significant effect", "effective", "slightly effective", and "no change" for how each was improved compared to before use. Regarding “skin familiarity”, “smoothness” and “smoothness / stickiness” indicate whether or not they felt during use, “felt well”, “somewhat felt”, “not much”, “not at all” "
The decision was made in four steps. The results are shown in Tables 4 to 6. In addition, the effective rate in a table means what was calculated more than effective.

[0041]

[0042]

[0043]

As is clear from the results in the table, the product of the present invention was confirmed to be effective as a lotion, and the improved solubility resulted in a chitosan having a limited dissolution range as a raw material. It was also confirmed that the efficacy was improved.

Next, a formulation example in which the chitosan derivative of the present invention is blended is shown. In addition, during the formulation of the formulation example, "suitable amount",
It means the amount which becomes 100% by weight in total.

<Prescription Example 1> Cream ( % by weight ) A Monostearic acid 2.0 Polyethylene glycol (40.EO) Self-emulsifying glyceryl monostearate 5.0 Stearic acid 5.0 Behenyl alcohol 1.0 Liquid paraffin 10. 0 Glyceryl trioctanoate 10.0 B Glycerin 5.0 Ethylparaben 0.1 Chitosan derivative (of compound No. 5 in Table 1) 4.0 Purified water qs A component belonging to A is heated and dissolved. Separately, the components belonging to B are dissolved by heating. B was added to A, stirred, emulsified and then cooled to produce a cream.

<Formulation Example 2> Emulsion ( % by weight ) A Polyoxyethylene sorbitan monostearate (20.E, O.) 1.0 Polyoxyethylene sorbite monostearate (60.E, O.) 0.5 Lipophilic glyceryl monostearate 1.0 Stearic acid 0.5 Behenyl alcohol 0.5 Avocado oil 4.0 Glyceryl trioctanoate 4.0 B 1,3-butylene glycol 5.0 Chitosan derivative (Compound No. 4 in Table 1) 8.0) Methylparaben 0.2 Purified water qs Dissolve the components belonging to A by heating. Separately, the components belonging to B are dissolved by heating. B was added to A, stirred, emulsified, and cooled to produce an emulsion.

<Formulation Example 3> Lotion ( % by weight ) Polyoxyethylene hydrogenated castor oil (60.E, O.) 8.0 Ethanol 15.0 Chitosan derivative (Compound No. 4 in Table 1) 5.0 Ethylparaben 0.1 Citric acid 0.1 Sodium citrate 0.3 1,3-butylene glycol 4.0 Disodium edetate 0.01 Purified water Appropriate amount Mix the above components, stir and dissolve uniformly to make up Water was produced.

<Formulation Example 4> Cream pack (% by weight) A Vegum 5.0 Squalane 2.0 Propylene glycol 5.0 Chitosan derivative (of Production Example 1) 0.5 Vitamin B ₁₂ 0.05 Purified water Appropriate amount B Zinc oxide 10.0 C Ethanol 5.0 A The components belonging to A are mixed, swelled by stirring, and B is added little by little. C was gradually added thereto and kneaded until a paste was obtained, thereby producing a cream pack.

Formulation Example 5 Essence ( % by weight ) Glycerin 20.0 Collagen 1.0 Elastin hydrolyzate 1.0 Ethanol 1.0 Chitosan derivative (Compound No. 4 in Table 1) 20.0 Purified water Amount The above components were mixed, uniformly stirred and dissolved to produce an essence.

<Formulation Example 6> Hydrophilic ointment ( % by weight ) A polyoxyethylene cetyl ether 2.0 glyceryl monostearate 10.0 liquid paraffin 10.0 vaseline 4.0 cetanol 5.0 B propylene glycol 10.0 Methylparaben 0.1 Chitosan derivative (manufactured in Production Example 2) 7.0 Purified water Amount A component belonging to A is heated and dissolved. Separately, the components belonging to B are dissolved by heating. B was added to A, stirred, emulsified, and cooled to produce a hydrophilic ointment.

<Formulation Example 7> Aerosol agent ( % by weight ) A Kojic acid 2.0 Chitosan derivative (compound number 2-3 in Table 2) 2.0 Benzyl nicotinate 0.01 Vitamin E acetate 0.05 Cetanol 1.2 Propylene glycol 4.0 Ethanol 8.0 Purified water Appropriate amount B LPG 7.0 A component belonging to A is uniformly mixed and dissolved, put into an aerosol container. Manufactured.

<Preparation Example 8> Poultice ( weight% ) A Polyvinyl alcohol 30.0 Sorbitan monooleate 1.0 Purified water 37.7 Aluminum chloride 0.3 Chitosan derivative (from Preparation Example 3) 10.0 Concentration The components belonging to glycerin 20.0 titanium oxide 1.0 A are dissolved by heating. Separately, the component belonging to B was heated and dissolved, stirred and mixed to produce a poultice.

<Prescription Example 9> Tablet Confectionery ( % by weight ) Citric acid 1.0 Skim milk powder 15.0 Sucrose fatty acid ester 1.0 Flavor 0.8 Chitosan derivative (of Production Example 1) 0.55 Granulated sugar 20 0.0 lactose 61.65 The above-mentioned raw materials were uniformly mixed, granulated, and tableted for production.

<Prescription Example 10> Candy ( % by weight ) A Powdered mavit 83.0 Citric acid 0.4 Chitosan derivative (compound No. 3-1 in Table 2) 0.799 Water 14.8 B Flavor 1.0 Yellow No. 4 Heat the mixture of 0.001 A with a vacuum pan under reduced pressure
After concentrating the solution to about 5%, transferring the solution to a cooling plate, adding B in order, cooling the solution to about 60 ° C., and molding it with a roller or a stamping machine.

<Prescription Example 11> Drink (in 100 ml ) Glucose, fructose, liquid sugar 1500 mg Chitosan derivative (of Production Example 1) 500 mg Honey 500 mg Vitamin C 300 mg Vitamin B6 5 mg Vitamin B12 1 mg Isoleucine 5 mg Phenylalanine 5 mg Guarana extract 1 ml Alcohol 1 ml Water Appropriate amount Flavoring amount The above ingredients were uniformly stirred and mixed to produce a drink.

[0057]

According to the present invention, a novel chitosan derivative having a specific structure is provided. This compound is stable in a wide pH range without impairing the hygroscopicity and excellent feeling of use of chitin / chitosan. It is suitable for use in various humectants as well as cosmetics and pharmaceuticals.

[Brief description of the drawings]

FIG. 1 is a graph showing the conductivity of a chitosan derivative of the present invention in comparison with chitosan and sodium hyaluronate.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ identification code FI A61K 47/36 A61K 47/36 (58) Fields investigated (Int.Cl. ⁷ , DB name) C08B 37/08 A61K 7/00 A61K 7/48 A61K 9/06 A61K 47/36 CA (STN)

Claims (2)

(57) [Claims] 1. The following formulas (a), (b) and (c) are irregularly distributed in a molecule, and the ratio of three structural units is: (a) N-acetyl-D-glucosamine structural unit; % (B) D-glucosamine constituent unit; 32 to 65% (c) D-glucosamine modified constituent unit; 3 to 18%. Embedded image Embedded image Embedded image Here, R in the above formula is any of formulas (1) to (5). (4) (5) (Where R ₁ represents a hydrogen atom or a methyl residue;
= 0 or n = 0, the same or different R ₂ , R ₃ , R ₄ and R ₅ , R
₆ and R ₇ are each a hydrogen atom, a methyl residue, a hydroxyl residue, an acetoxy residue, or an acetylthio residue;
Further, the groups R ₂ and R ₃ or the groups R ₅ and R ₆ together form a methylene group, or m = 1 or n = 1
, R ₂ , R ₃ , R ₄ or R ₅ , R ₆ , R
₇ represents a hydrogen atom. ) 2. A humectant comprising the chitosan derivative according to claim 1 as an active ingredient.