JP2798514B2 - Inclusion compound of γ-cyclodextrin and method for separation and purification of γ-cyclodextrin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel γ-cyclodextrin inclusion compound. Further, the present invention provides a γ-
The present invention relates to a method for efficiently separating and purifying γ-cyclodextrin from various cyclodextrin mixtures containing cyclodextrin.

[0002]

BACKGROUND ART Cyclodextrins (hereinafter abbreviated as CDs) are cyclodextrin glucanotransferases (hereinafter referred to as CGTa) produced by Bacillus macerans or Bacillus stearothermophilus on starch.
Abbreviated as se. ) Has been known for a long time to act.

[0003] The resulting CDs include γ-cyclodextrin (hereinafter referred to as γ-cyclodextrin) having eight glucoses bonded in a ring.
Abbreviated as CD. ), The six glucoses are cyclically α-
1-4-linked α-cyclodextrin (hereinafter referred to as α-cyclodextrin)
Abbreviated as CD. ), Β-cyclodextrin (hereinafter abbreviated as β-CD) in which seven glucoses are bound in a cyclic manner.

[0004] When CGTase is allowed to act on waxy maize or branched dextrin which is rich in amylopectin, branched cyclodextrins are generated and the above-mentioned ordinary unbranched CDs are also generated.

[0005] These CDs generally have the property of enclosing various substances, but have the selectivity of the substance (guest) to be incorporated depending on the type of the CD (host), and the size of the CD cavity and the steric size of the guest molecule. Is considered to be stable and easily included when conformed.

[0006] CDs exhibit a function of solubilizing hardly water-soluble substances, a function of stabilizing unstable substances, a function of preventing volatile substances from volatilizing, a function of masking off-flavors, and a function of catalyzing chemical reactions.
These functions are thought to be related to the inclusion effect in which the lipophilic substance is enveloped in the three-dimensional cavity of CDs. For this reason, depending on the desired expression function, various CDs often interfere with each other.
In such a case, it is ideal to use a single CD of high purity.

[0007] For example, γ-CD is useful as a pharmaceutical-related application for stabilizing the retention of a drug, solubilizing the drug, promoting absorption in the body, preventing deliquescent, and powdering an oil-and-fat base. It is useful for solubilization of drugs, promotion of penetration into the skin and suppression of irritation, stabilization of fragrances, and powdering of oil bases. However, as described above, it is natural that γ-CD desirably has high purity in order to exert such a function more effectively.

By the way, CGTas is added to the above-mentioned starch.
e, the reaction mixture obtained by the reaction contains various CDs and acyclic dextrins as described above, and separating only γ-CD from these contains γ-C
Since D is a substance having extremely high solubility in water and being difficult to crystallize, it is very difficult, and furthermore, a high cost is required to increase the purity by using a solvent or the like.

The following methods are known as typical methods for separating CDs from the above reaction mixture.

(1) A method in which an organic solvent such as acetone is added to a sugar solution to precipitate CDs (see Japanese Patent Publication No. 52-8385).

(2) A method of purifying using an anion exchange resin (see Japanese Patent Publication No. 46-9223).

(3) A method using a hydrophobic synthetic adsorption resin composed of a porous polymer (see JP-A-56-805).

(4) A method of fractionating with an alkali metal salt of a strongly acidic ion exchange resin (see JP-A-57-30702).

[0014]

However, the above methods (1), (2), (3) and (4) are somewhat effective when CDs are separated from other oligosaccharides or dextrins. However, these methods are expensive and cannot be used for the purpose of industrially separating only γ-CD with high purity.

An object of the present invention is to solve the problems of the prior art and to provide a method for easily separating and purifying high-purity γ-CD from a mixture of various CDs. Further, the present invention provides, for example, γ-CD as an intermediate of γ-CD as a final product in the above-mentioned γ-CD separation and purification method.
It is also an object to provide an inclusion compound of CD.

[0016]

Means for Solving the Problems In view of the above-mentioned situation in the art, the present inventors have conducted intensive studies in order to find an efficient and practical method for separating γ-CD. It was found that ether selectively included only with γ-CD.

That is, the present inventors have considered that the studies on the inclusion activity of CDs are mostly limited to the interaction with low molecular weight compounds, so that the interaction between various water-soluble polymers and CDs is considered. Was considered. Table 1 lists the yields of the clathrate compound of polymer and γ-CD when 20 mg of each water-soluble polymer was added to 1 ml of a saturated aqueous solution of γ-CD and reacted at about 25 ° C. for 10 minutes with stirring. .

[0018]

[Table 1] Polymer (average molecular weight) Yield (%) Polyvinyl alcohol (degree of polymerization: 500) 0 Polyvinyl alcohol (degree of polymerization: 2,000) 0 Polyacrylamide (10000) 0 Polyvinylpyrrolidone (10000) 0 Polyethylene glycol (10000) 0 Polymethylvinyl ether * 72 * [Tokyo Chemical Industry Co., Ltd.]

Further, as a result of the same experiment as in Table 1,
It was found that oligosaccharides, polysaccharides, and monosaccharides containing CDs other than γ-CD (including branched CDs) did not form complexes with polymethyl vinyl ether such as inclusion compounds.

The present invention has been completed based on the above findings.

That is, according to the present invention, γ-
An object of the present invention is to provide an inclusion compound of γ-cyclodextrin in which a polymethyl vinyl ether molecule is included in a cyclodextrin molecule.

Further, the present invention relates to a method for producing an insoluble inclusion compound of γ-cyclodextrin by mixing a mixture of various cyclodextrins containing γ-cyclodextrin and polymethyl vinyl ether to form an insoluble γ-cyclodextrin clathrate.
An object of the present invention is to provide a method for separating and purifying γ-cyclodextrin, which comprises removing polymethyl vinyl ether from a cyclodextrin inclusion compound.

Hereinafter, the present invention will be described in detail. Examples of the polymethyl vinyl ether used in the present invention include those manufactured by Tokyo Chemical Industry Co., Ltd., and Lutonal M4 manufactured by BASF.
0 (trade name) is commercially available, the former can be obtained in the form of a 30% aqueous solution or methanol solution, and the latter is a solvent-free, 50% aqueous solution, 70% ethanol solution,
It is available in the form of a 70% toluene solution.

15 mg of polymethyl vinyl ether (manufactured by Tokyo Kasei Kogyo Co., Ltd.) is added to 1 ml of a saturated aqueous solution of γ-CD.
After stirring at 25 ° C. for 10 minutes, an inclusion compound of polymethyl vinyl ether and γ-CD was formed. At this time, the yield of the clathrate compound was 72%.

In addition, in order to confirm that γ-CD forms an inclusion compound with polymethyl vinyl ether, a thermogravimetric analyzer TGA-50 (manufactured by Shimadzu Corporation) was used to perform a thermogravimetric analysis. Was done.

FIG. 3 shows that γ-CD (sample amount: 7.34).
In the figure, Curve 1 is a temperature curve (heating rate: about 10 ° C./min), and Curve 2 is a weight curve of the sample. Curve 3 is a differential curve of sample weight loss (weight loss per unit time (mg /
Min)). The horizontal axis in FIG. 3 represents time, and the unit is minute (m
in). The vertical axis on the right side of FIG. 3 represents the temperature, and one scale is given every 50 ° C. The vertical axis on the left side of FIG. 3 indicates the sample weight (mg) and the amount of sample weight reduction per unit time (m).
g / min). In the case of the sample weight, it is an account with one scale every 0.7 mg, and in the case of the weight loss per unit time, one scale is attached every 0.5 mg / min. Account.

FIG. 3 shows that the thermal decomposition temperature of γ-CD (the temperature at the end point of the rapid weight loss) is 323.8 ° C.

FIG. 4 shows the inclusion reaction product of γ-CD and polymethyl vinyl ether (sample amount: 3.77).
4 mg) shows the results of thermogravimetric analysis. In the figure, curve 4 is a temperature curve (heating rate: about 10 ° C./min), curve 5 is a sample weight curve, and curve 6 is a sample weight. Differential curve of decrease [weight loss per unit time (mg /
Min)]. The horizontal axis of FIG. 4 represents time, and the unit is minute (m
in). The vertical axis on the right side of FIG. 4 represents the temperature, and one scale is given every 50 ° C. The vertical axis on the left side of FIG. 4 represents the sample weight percent and the sample weight reduction per unit time (mg / min). In the case of the sample weight percent, the account is a scale with a scale of 11%. In the case of the sample weight loss amount, the account is provided with one scale every 0.3 mg / min.

FIG. 4 shows that the thermal decomposition temperature of the inclusion reaction product of γ-CD and polymethyl vinyl ether was 338.6 ° C., indicating that the inclusion compound was formed by the above reaction.

As a result of a quantitative study of the formation of the clathrate compound, one monomer unit was obtained for one monomer unit of polymethyl vinyl ether.
It was found that γ-CD of the molecule was bound. This was also confirmed by the ¹ H-NMR spectrum. It has also been found that the length of methyl vinyl ether of two monomer units corresponds to the length of the cavity of γ-CD. FIG. 1 is a model diagram of the structure of an inclusion compound of polymethyl vinyl ether and γ-CD deduced from the results. In FIG. 1, the shaded portion is γ-C
It may be considered as a cross section of D.

FIG. 2 is a diagram showing a powder X-ray diffraction pattern of an inclusion compound of methyl vinyl ether and γ-CD manufactured by Tokyo Chemical Industry Co., Ltd. In FIG. 2, θ on the abscissa represents the diffraction angle, and CPS on the ordinate represents the reflection intensity (count / sec). From FIG.
The clathrate is crystalline and appears to form a channel-type structure.

Next, the method for separating and purifying γ-CD of the present invention will be described in detail. This method includes, for example, contact-mixing a sugar solution containing various CDs and further a non-cyclic dextrin with polymethyl vinyl ether to form an insoluble clathrate compound of γ-CD and polymethyl vinyl ether. In this method, a precipitate is formed, and then the precipitate is solid-liquid separated from the mixture, and polymethyl vinyl ether is released by an operation described later to separate γ-CD.

The mixing ratio of the above-mentioned sugar solution and polymethyl vinyl ether may be usually 2 mol or more as methyl vinyl ether unit per 1 mol of γ-CD, and polymethyl vinyl ether is required. It is not preferable to use such a large amount in terms of cost.

The solid-liquid separation can be performed by a general separation means such as filtration, centrifugation, membrane separation using an ultrafiltration membrane or the like.

The rate at which γ-CD forms an inclusion compound with polymethyl vinyl ether is extremely high, and a reaction time of several minutes is sufficient.

Next, polymethyl vinyl ether and γ
An operation for releasing polymethyl vinyl ether from the inclusion compound with CD will be described.

After the precipitate of the clathrate compound separated and washed from the reaction mixture is dried if necessary, an appropriate organic solvent is added thereto, and the mixture is stirred, whereby polymethyl vinyl ether is liberated from the clathrate compound and dissolved in the solvent. Γ-C
D remains as a precipitate. When the solvent containing polymethyl vinyl ether is removed from the suspension by a common solid-liquid separation means such as filtration, centrifugation, or membrane separation using an ultrafiltration membrane, crystals of γ-CD are formed. can get.

Specific examples of the above-mentioned organic solvent include lower alcohols such as methanol, ethanol and propanol, and halogenated hydrocarbons such as dichloromethane.

As another method, when the inclusion compound precipitate is suspended in water and heated to a temperature of 70 ° C. or higher, the inclusion force is weakened and polymethyl vinyl ether is released,
Since both polymethyl vinyl ether and γ-CD are dissolved in water, the resulting aqueous solution can be separated, for example, by subjecting it to column chromatography at a relatively high temperature or by concentrating and hot-filtrating.

As still another method, the precipitate of the clathrate is suspended in water, and benzoic acid, phenol, or another substance having a higher clathrating power with γ-CD than polymethyl vinyl ether is added. -The polymethyl vinyl ether included in the CD is replaced and included, and the polymethyl vinyl ether is released. Since polymethyl vinyl ether and the new inclusion compound are often dissolved in water, the resulting aqueous solution can be separated by, for example, column chromatography or concentration and filtration. If this new clathrate has a useful application, it will further
-There is no need to separate and purify CD, which is reasonable.

[0041]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples, but it goes without saying that the present invention is not limited to the examples.

Example 1 10% by weight of a CD mixture (composition: α-CD 30% by weight, β
-An aqueous solution containing 30% by weight of polymethyl vinyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.) is added to 100 ml of an aqueous solution containing 15% by weight of CD, 5% by weight of γ-CD, and 50% by weight of dextrin, and stirred and mixed at room temperature for 30 minutes. Then, an inclusion compound of polymethyl vinyl ether and γ-CD was precipitated.

The obtained suspension was filtered with a filter using a filter paper having a pore size of 0.45 μm, and the precipitate of the clathrate was separated and washed with 200 ml of pure water.

Next, the precipitate was transferred to a beaker, and
After adding 100 ml of 9.5% ethanol and stirring, substantially only the polymethyl vinyl ether dissolves in ethanol and is released, so the resulting suspension is filtered, and the residue is washed with 99.5% ethanol. Thus, pure γ-CD could be obtained.

[0045]

The inclusion compound of γ-CD of the present invention is pure γ-CD
It can be used as an intermediate for preparing CD, and can be easily prepared as a precipitate by mixing a mixture of various cyclodextrins including γ-CD and polymethyl vinyl ether in the presence of water. .

According to the method for separating and purifying γ-CD of the present invention,
After the inclusion compound of γ-CD is prepared, polymethyl vinyl ether can be easily removed from the inclusion compound, so that high-purity γ-CD can be produced at low cost. The γ-CD thus prepared has an advantage that it can be completely used for food, medicine, cosmetics, etc. because polymethyl vinyl ether has low toxicity.

[Brief description of the drawings]

FIG. 1 shows polymethyl vinyl ether of the present invention and γ-C
FIG. 4 is a model diagram of a deduced structure of an inclusion compound with D, showing a state where a methyl vinyl ether unit is included in a hatched portion of γ-CD.

FIG. 2 is a diagram showing a powder X-ray diffraction pattern of an inclusion compound of the present invention comprising polymethyl vinyl ether and γ-CD.

FIG. 3 is a diagram showing the results of thermogravimetric analysis of γ-CD.

FIG. 4 is a diagram showing the results of thermogravimetric analysis of the inclusion compound of the present invention between polymethyl vinyl ether and γ-CD.

Claims (3)

(57) [Claims] 1. Inclusion compound of γ-cyclodextrin in which polymethyl vinyl ether molecule is included in γ-cyclodextrin molecule constituting the inclusion lattice. 2. A mixture of various cyclodextrins containing γ-cyclodextrin and polymethyl vinyl ether are mixed in the presence of water to form an insoluble γ-cyclodextrin inclusion compound, and then the γ-cyclodextrin A method for separating and purifying γ-cyclodextrin, comprising removing the polymethyl vinyl ether from an inclusion compound. 3. The γ-cyclodextrin clathrate according to claim 2, wherein said polymethyl vinyl ether is removed from said γ-cyclodextrin clathrate by adding an organic solvent to said γ-cyclodextrin clathrate. −
A method for separating and purifying cyclodextrin.