JPH0212960B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for purifying ginsenoside-Rg ₁ .

(Ginsenoside-Rg ₁ ) Ginsenoside-Rg ₁ is a compound represented by the following formula, and is derived from Panax ginseng (Panax ginseng C.
A.Mey) is contained in the roots.

Ginseng has long been known as an important drug in Chinese medicine, and is listed in the Japanese Pharmacopoeia as either ``ginseng'' or ``red ginseng'' depending on the treatment method. Among the components of ginseng, several types of saponins, such as ginsenoside-Rg ₁ , are known. These are included as a mixture. Therefore, it is not easy to separate only ginsenoside-Rg ₁ from these mixtures.

By the way, ginsenoside-Rg ₁ was originally known to have a central activating effect, but in recent years it has been revealed that it has a platelet aggregation inhibitory effect, and it has come to be said to be effective in preventing arteriosclerosis. (Kozo Nakanishi et al., 1982, Clinical and Research 59,
3671-3674). Furthermore, it has recently been revealed that ginsenoside-Rg ₁ has the effect of improving blood lipid levels in hyperlipidemic animals (Masahiro Yamamoto et al., Journal of the Japanese and Chinese Pharmaceutical Society 2, 377-385). In addition, ginsenoside-Rg ₁ has come to be used as a standard reagent for thin-layer chromatography in confirmation tests for "Red ginseng" and "Ninjin" in the 11th edition of the Japanese Pharmacopoeia. Thus, ginsenosides
Rg ₁ has become an important compound, and it has therefore become necessary to devise a suitable method for purifying it.

(Prior Art) However, until now, it was only known that crude drugs can be separated from extracts by column chromatography (hereinafter referred to as column chromatography). In other words, ginsenoside-Rg ₁ (hereinafter referred to as Rg ₁ ) has been obtained by fractionating the various types of saponin-containing substances mentioned above using column chromatography, but in reality, it is still not pure. Therefore, in order to purify it, a complicated method was adopted in which it was first converted into an acetyl derivative, separated, and then the acetyl group was removed from the acetyl derivative to return it to Rg ₁ . (Y.NAGAI et al., Tetrahedron Vol.27,
pp881 [1971]). There, the thus obtained Rg ₁ was further purified by recrystallization in n-butanol-methyl ethyl ketone. but,
Such a purification method is extremely complicated and is not easy to implement industrially.

Incidentally, the above-mentioned literature describes that the compound thus purified was semicrystalline, with a melting point of 194 to 196.5°C and a property of [α] ¹⁹ _D = +32° (pyridine).

(Problems to be Solved by the Invention) The object of the present invention is to provide a method for easily separating only Rg ₁ from a mixture of saponins as described above.

(Means for Solving the Problem) The inventor found that it is difficult to obtain Rg ₁ with good purity just by fractionating Rg ₁ by column chromatography. However, if the fraction obtained by column chromatography is dissolved in cold water, e.g., water at 4°C to create a saturated solution, and this saturated solution is separated and brought to a higher temperature, e.g., 28°C, It was discovered that Rg ₁ precipitates in an aqueous solution. Furthermore, they discovered that the precipitate forms beautiful crystals. Furthermore, the inventor discovered that, unlike ordinary organic compounds, especially other compounds mixed therein, Rg ₁ has the property that its solubility decreases as the temperature rises around room temperature, and for this reason, the above-mentioned We have found that results can be obtained. This invention was made based on such knowledge.

(Summary of the Invention) This invention dissolves a material containing Rg ₁ in water to create a saturated solution at a specific temperature within the range of 0°C to 20°C, and separates this saturated solution.
The present invention relates to a method for purifying Rg ₁ , which is characterized by maintaining the temperature at 20°C to 30°C and removing a crystalline solid precipitated in an aqueous solution.

In this invention, as a material containing Rg ₁ , a material fractionated by column chromatography is used. In column chromatography, a solid is packed into a cylinder to serve as a stationary phase, a sample mixture is placed at one end of the column, and the mixture is moved into the stationary phase using an appropriate developing agent. This method uses differences in movement speed to separate mixtures. Various solids can be used as the solid that constitutes the stationary phase, such as silica gel, activated alumina, etc., and various solvents and gases can be used as the developing agent. Column chromatography is one of the methods for separating mixtures, so
Naturally, Rg ₁ should be able to be separated by column chromatography. However, actually obtaining highly pure Rg ₁ by column chromatography requires complicated operations and therefore requires a lot of time and materials. Moreover, the material obtained by column chromatography is likely to be accompanied by ginsenosides Rg ₃ , Rg ₂ , Rf, etc., and if these are attempted to be removed by column chromatography, the yield will be extremely reduced.

In this invention, a saturated solution is first created by dissolving a material containing Rg ₁ in water. As water, it is preferable to use water from which ions have been removed using an ion exchange resin or distilled water. The temperature at which the saturated solution is prepared is desirably as low as possible, and specifically can be a specific temperature within the range of 0°C to 20°C. Naturally, in order to obtain a saturated solution, a large amount of material containing Rg ₁ is poured into water, stirred well for several minutes to dissolve it, and the insoluble matter is removed to form a saturated solution. It is desirable to do so.

In this invention, Rg ₁ is precipitated by maintaining the above saturated solution at a temperature of 20° to 30°C. For example, 4
When a saturated solution is obtained at 28°C, it is left at 28°C overnight to precipitate a solid in the solution. in this way,
It is extremely rare for a saturated solution obtained at a low temperature to be maintained at a high temperature, resulting in the precipitation of solids in the solution. This is because, as mentioned above, unlike ordinary compounds, Rg ₁ decreases its solubility in water as the temperature increases around room temperature. This happens based on the characteristics of

In this invention, after a solid is precipitated in an aqueous solution as described above, this solid is taken out. For this purpose, the aqueous solution is decanted or filtered. The solid thus extracted is a beautiful crystal and is Rg ₁ with high purity.

(Effect of the invention) According to the method of this invention, a material containing Rg ₁ is dissolved in water to create a saturated solution at a specific temperature within the range of 0° to 20°C, and this is separated. Rg ₁ can be isolated as crystals by simply maintaining the saturated solution at a temperature of 20-30°C and removing the crystalline solid that precipitates in the aqueous solution. Moreover, 0° to 20°C
Both the specific temperature within the range of 20 and 30° C. are extremely common temperatures, so it is easy to maintain them at these temperatures. in addition,
The crystals thus obtained are beautiful. Furthermore, the amount of crystals thus obtained is large. For example, at 4°C, 10g of Rg ₁ can be dissolved in 100Ω of water. If this is heated to 28℃, this will be 7g.
Since crystals of Rg ₁ can be precipitated,
This means that Rg ₁ can be precipitated with a yield of 70%, which means that the yield is good. This invention brings such remarkable effects.

The details of the method of this invention will be explained below with reference to Examples.

Example 10 g of powder containing ginsenoside-Rg ₁ obtained by column chromatography fractionation and from which the solvent was removed was dissolved in 100 ml of deionized water at 4° C. with stirring, and the residue was filtered. When the solution thus obtained was left at 28°C overnight, crystals were precipitated in the solution. The crystals were collected by filtration and dried to obtain 7 g of crystals.

This crystal had a melting point of 208-211°C and [α] ²² _D : +33.9°. This crystal can be obtained by thin layer chromatography (chloroform:methanol:water = 65:35:10).
(lower layer) confirmed that it did not contain any impurities.

Claims (1)

[Claims] 1 Dissolve the material containing ginsenoside-Rg ₁ in water to create a saturated solution at a specific temperature within the range of 0° to 20°C, and then heat the saturated solution to 20° to 30°C.
1. A method for purifying ginsenoside-Rg ₁ , which comprises maintaining the temperature at a temperature of 100 mL to separate a crystalline solid precipitated in an aqueous solution.