KR950007250B1 - Process for preparing saponin - Google Patents

Abstract

The method for preparing Ginsenoside Rh2 of formula (I) comprises extraction and alkali decomposition of white ginseng, leaf of panax ginseng or dolwae powder with a lower alcohol and a strong alkali; condensation reaction of the obtd. non-sugar part with bromine sugar in the presence of a catalyst; and removal of the residual acetyl gp. The lower alcohol is pref. methanol, ethanol or butanol; the strong alkali is pref. metal sodium, potassium hydroxide, sodium hydroxide, sodium methoxide, potassiun methoxide or potassium ethoxide.

Description

Method of preparing saponin

The present invention relates to a method for preparing ginsenoside Rh ₂ which is ginseng saponin represented by structural formula (I).

[Formula 1]

It is also an object of the present invention to provide a new and advanced preparation method for the structural formula (I), which is saponin phosphate with anticancer activity.

Briefly, the present invention relates to a method for preparing ginsenoside Rh ₂ , which is ginseng saponin of structural formula (I), by extracting and isolating non-sugar 20 (S) -protopanaxadiol ratio from white ginseng, ginseng leaf or Dol et al.

The compound of formula (I) prepared by the present invention is a ginseng saponin having a wide range of anticancer effects, isolated and structured from red ginseng by Odashima et al. (Japanese Patent Publication No. 89-28759). Little is known. In addition, Abe et al., New Biologically Active Naturals, Chapter 5, 316, 1988 reported the hepatitis therapeutic activity of these substances.

However, according to Kitagawa et al. (Japan Pharmaceutical Magazine, 103, 612, 1983), the compound of formula (I) is known to be present in trace amounts only in red ginseng, not in white ginseng.

Therefore, there is a need for a method for obtaining a large amount of pure compound of formula (I), and the compound of structure (I) was isolated by chemical treatment in Japanese Patent Publication No. 89-28759, but the yield was not satisfactory at 0.01%. Can not do it. Therefore, the present inventors focus on the fact that the non-sugar portion of Structural Formula (I) is 20 (S) -protopanaxadiol, and white ginseng and ginseng leaf which are cheaper than red ginseng containing a large amount of 20 (S) -protopanaxadiol. Alternatively, it was found that by obtaining a non-glycoside in a stone and glycosides it, the compound of formula (I) can be obtained in high yield.

Shibata et al. (Shibata, et al., Chem, Pharm. Bull., 20, 1212, 1972) used an acid hydrolysis reaction as a method for obtaining the intrinsic fructose of structural formula (I). Secondary transformations produce artifacts.

In addition, Kitagawa et al. (Tetrahedron Letters, 30, 2283, 1974) used soil bacteria hydrolysis, De Mayo, et al., Canad. J. Chem., 43, 2033. (1965) suggests Demeier decomposition, but all are complex or have poor yields. In addition, when the general method is used in the preparation of the crude extract, the process may be complicated and loss of the target ingredient may occur.

In addition, many methods have been reported since the synthesis of glycosides since the Koenigs-Knorr method (Koenigs, W., and Knorr, E., Ber., 34, 957, 1901) was reported in 1901. Enemy or difficult reaction conditions.

Moreover, in the case of non-sugar parts of the structural formula (I), glycosides cannot be synthesized under conditions of heating because of heat instability.

Accordingly, an object of the present invention is to provide a method for preparing ginseng saponin, which is a structural formula (I) having an activity under mild conditions by extracting a large amount of the non-sugar portion of the structural formula (I) simultaneously with extraction.

Briefly describing the present invention, extraction from white ginseng, ginseng salt or dolol other crudes and complete alkali decomposition to prepare a large amount of non-sugar parts of the structural formula (I) without a secondary change, this is a mixed catalyst of silver carbonate and cadmium carbonate It is a method to obtain the compound of formula (I) in high yield by performing glycoside reaction with bromine sugar in the presence of (I) (total yield 0.6% (w / w))

This will be described in more detail as follows.

White ginseng, ginseng salt or dolot is used as a coarse extract, which is extracted with lower alcohol and strong alkali, and completely alkaline decomposed in an oil bath to obtain 20 (S) -propanoparanadiol, which is a true non-sugar of structural formula (I).

At this time, as the lower alcohol, anhydrous methanol, anhydrous ethanol or anhydrous butanol is suitable, and as strong alkali, metal sodium, potassium hydroxide, sodium hydroxide, sodium methoxide, sodium ethoxide, potassium methoxide or potassium ethoxide is suitable.

After 20 (S) -protopanaxadiol, which is obtained from above, is glycosided with bromine sugar in the presence of a mixed catalyst of silver carbonate and cadmium carbonate, the remaining acetyl group is removed using 0.2 N-potassium carbonate / 80% aqueous methanol. To obtain ginseng saponin of formula (I).

The features of the present invention are summarized as follows.

Firstly, non-sugar part of structural formula (I) is prepared from herbal raw materials by complete alkali decomposition, and glycoside reaction is performed to obtain high yield of compound of structural formula (Ⅰ).

Second: It is much more economical by shortening the general extraction process by decomposing alkali at the same time as extraction in manufacturing non-sugar part of structural formula (Ⅰ).

Third: It can be easily manufactured from all herbal medicines having the non-sugar portion of structural formula (I) as an intrinsic non-sugar portion.

Fourth: in the moderated conditions using a mixed catalyst during glycoside reaction, it is a synthesis method.

Specific examples of preparing ginseng saponin of formula (I) according to the present invention will be described in detail in the following examples, and the present invention is not limited by the following description.

Example 1

Extraction and purification of 20 (S) -protopanaxadiol

100 g of phosphate is prepared as a crude powder. To 800 ml of anhydrous ethanol in an ice bath, 60 g of sodium methoxide (Aldrich. 16, 499-2) is added in small portions to a completely dissolved reaction solution.

The reaction solution is heated to reflux for 48 hours with stirring on an oil bath. After completion of the reaction, 800 ml of distilled water was added, which was extracted three times with 800 ml of ethyl acetate. The ethyl acetate layer was isolated and neutralized with an aqueous solution of 1500 ml of saturated sodium chloride. Then, 1500 ml of distilled water was added, and the mixture was washed with water, and the ethyl acetate layer was dehydrated with anhydrous magnesium sulfate and filtered.

The filtrate is evaporated under reduced pressure to give 5 g of dry decomposition products.

After completely dissolving this in 24 ml of a mixed solution of n-hexane-acetone (1: 2), 6 g of silica gel (Merck, 70-230mesh) was added thereto, dried under reduced pressure, and completely adsorbed onto the silica gel. The adsorbate was separately added to the top of the column packed with 390 g of silica gel (Merck, 70-230mesh).

Subsequently, the mixture was eluted with a mixed solvent of n-hexane-acetone (5: 1) to obtain a fraction, and 720 mg of the title compound was obtained by distillation under reduced pressure and crystallization (yield 0.72% (w / w)).

¹ H-NMR (CDCl ₃ , δ): 0.78 (3H, S), 0.88 (6H, S), 0.98 (6H, S), 1.16 (3H, S), 1.61, 1.68 (3H each, boths). 8 × -CH ₃ , 2.8,3.2,3.6 (1H each, broad S, 3 × -OH), 5.16 (1H, t-like, C ₂₄ -H).

¹³ C-NMR (pyridine-d ₅ , δ): 78.1 (C-3), 71.0 (C-12), 54.8 (C-17), 73.0 (C-20), 27.1 (C-21), 35.9 ( C-22), 126.3 (C-24), 130.7 (C-25).

Example 2

Preparation of Ginsenoside Rh ₂

20 mg of dichloromethane was dissolved in 200 mg (0.43 mmol) of the title compound isolated in Example 1. After shielding the reaction tank, 142 mg (0.52 mmol, 1.2 eq.) Of carbonate and 82 mg (0.47 mmol, 1.1 eq.) Of cadmium carbonate were added thereto and stirred at room temperature for 5 minutes.

Then add 270 mg (0.65 mmol, 1.5 eq.) Per bromine and stir at room temperature for 35 minutes. After confirming the reaction, the reaction vessel was diluted with 40 ml of dichloromethane, filtered, and dried under reduced pressure to obtain 400 mg of crude product.

To this, 500 mg of silica gel (Merck, 70-230mesh) was added, and the crude product was completely adsorbed onto the silica gel and separately added to the top of the column filled with 35 g of silica gel (Merck, 70-230mesh). This was eluted with a mixed solvent of n-hexane-acetone (4: 1) to obtain a fraction. The solvent was evaporated under reduced pressure, and then recrystallized with chloroform-methanol to give a colorless needle of 3-0- (2 ', 3). 160 mg of ', 4', 6'-tetra-O-acetyl-β-D-glucopyranosyl) -20 (S) -protopanaxadiol was obtained (yield 46.6%).

¹ H-NMR (CDCl ₃ , δ): 0.81-1.69 (8 × CH ₃ ), 1.98 (3H, S), 2.02 (6H, S), 2.09 (3H, S). 4x-OAc, 4.67 (1H, d, J = 7.2 Hz, Anomeric Proton), 5.07 (1H, t-like, C ₂₄ -H).

80 mg of the colorless needles obtained above are dissolved in 8 ml of 0.2 N-potassium carbonate / 80% aqueous methanol and stirred at room temperature for 2 hours to deacetylate.

This is neutralized with Dowex 50W × 8 (H ⁺ ), filtered, and the filtrate is extracted with 10 ml of n-butanol. The n-butanol layer was separated and dried under reduced pressure to give 75 mg of the title compound by crystallization.

¹³ C-NMR (pyridine-d5, δ): 88.9 (C-3), 71.1 (C-12), 73.2 (C-20), 126.4 (C-24), 130.1 (C-25), 106.5 (D -glucose moiety, C-1 '), 75.8 (C-2'), 78.7 (C-3 '), 72.3 (C-4'), 78.0 (C-5 '), 63.5 (C-6').

Claims (4)

Extract the dry powder of white ginseng, ginseng leaf or dol using low alcohol and strong alkali and completely decompose it at the same time to obtain bard sugar part of Structural Formula (I), and remove residual acetyl group after condensation reaction with bromine sugar in the presence of catalyst. Method of producing a structural formula (I), characterized in that consisting of steps. The lower alcohol used in claim 1 is methanol, ethanol or butanol. The method according to claim 1, wherein metal alkali, potassium hydroxide, sodium hydroxide, sodium methoxide, sodium ethoxide, potassium methoxide or potassium ethoxide is used as strong alkali. The method according to claim 1, wherein silver carbonate and cadmium carbonate are mixed and used as a catalyst in the condensation reaction.