CN113968894B

CN113968894B - Method for preparing cycloastragenol by degrading astragaloside IV

Info

Publication number: CN113968894B
Application number: CN202111305277.1A
Authority: CN
Inventors: 潘继刚; 黄月君; 张钧
Original assignee: Fu Kanglihua Shanxi Biotechnology Co ltd; Shanxi University
Current assignee: Fu Kanglihua Shanxi Biotechnology Co ltd; Shanxi University
Priority date: 2021-11-05
Filing date: 2021-11-05
Publication date: 2024-05-28
Anticipated expiration: 2041-11-05
Also published as: CN113968894A

Abstract

The invention discloses a method for preparing cycloastragaloside by degrading astragaloside, which is a method for preparing cycloastragaloside by degrading astragaloside in a mixed medium formed by fatty alcohol-organic solvent by using solid acid slightly dissolved in a reaction medium as a catalyst. Specifically, astragaloside IV is used as a raw material, fatty alcohol is used as a degradation reagent in a medium formed by fatty alcohol-organic solvent, and under the catalysis of solid acid, the glycosidic bond of the astragaloside IV is degraded to remove xylosyl and glucosyl so as to obtain the cycloastragaloside. The degradation reaction condition is mild, the defect that the generated cycloastragal is further converted into the astragal or other byproducts is avoided, and the yield of the cycloastragal can reach more than 50 percent generally. The method has the advantages of simple operation steps, short degradation reaction time, high product purity and low preparation cost, and is suitable for industrial production.

Description

Method for preparing cycloastragenol by degrading astragaloside IV

Technical Field

The invention belongs to the field of pharmaceutical chemical industry, and in particular relates to a method for preparing cycloastragenol by degrading astragaloside IV.

Background

Astragalus root is used as a traditional important Chinese medicine, and the medicinal use has been two thousand years old so far. It has effects of strengthening body resistance, consolidating constitution, invigorating middle warmer and qi. Astragaloside IV is used as the most main saponin substance in Astragalus mongholicus, and has effects of enhancing organism immunity, improving organism disease resistance, resisting fatigue, protecting liver, scavenging free radicals in vivo, and inhibiting osteoclast. The content of astragaloside IV is an important index for judging the quality of astragalus Chinese medicinal materials at present.

Astragaloside IV can be degraded into cyclic Astragaloside alcohol which is easy to be absorbed and utilized by intestinal flora in the organism, and the molecular mass and the steric hindrance of the cyclic Astragaloside alcohol are smaller than those of the Astragaloside IV, and the cyclic Astragaloside IV has relatively good fat solubility and is easy to be absorbed by the organism through cell membranes. Related researches report that the cycloastragenol can be used as a telomerase activator to delay shortening of telomeres, increase cell division times and effectively inhibit cell aging. Therefore, the cycloastragenol has good application prospect in anti-aging.

The currently reported methods for preparing the cycloastragaloside from the astragaloside IV mainly comprise three conditions of an enzymolysis method, a Smith degradation method and an acid hydrolysis method. 1) Chinese invention discloses patent: CN105566434a; CN105734109a; CN106011213a; CN107058445A; CN111849959a; the preparation of cycloastragenol is mainly carried out by enzyme catalysis in CN111893158A and other documents. Although the enzymolysis method has higher conversion rate, the enzymolysis method has more severe requirements on reaction conditions, complicated steps and long preparation period, and is not beneficial to large-scale preparation. 2) Chinese invention discloses patent: CN13880910B; the CN106083979A and other documents prepare the cycloastragenol through Smith degradation by an oxidation-reduction method, but the preparation process needs to use an oxidant and a reducing agent to carry out oxidation-reduction reaction, so that the preparation steps are too many, and the practicability is not high. 3) Chinese invention discloses patent: CN102030799a; CN104817610a; CN1099942663a and the like are a method for preparing cyclic astragalus alcohol by acid hydrolysis of astragaloside iv with hydrochloric acid and sulfuric acid. The acid hydrolysis method is simple to operate and low in cost, and is the main method for preparing the cycloastragenol at present. However, the cyclic astragalus alcohol is easily converted into the byproduct astragalus alcohol under severe acidic conditions, the reaction conditions are difficult to control, and the yield is often low.

Disclosure of Invention

The invention aims to provide a method for preparing cycloastragenol by degrading astragaloside IV, which has the advantages of mild reaction conditions, higher yield and less byproducts.

The invention provides a method for preparing cycloastragaloside by catalyzing astragaloside IV with solid acid, which takes astragaloside IV as a raw material, takes bisulfate slightly dissolved in degradation medium as a solid acid catalyst, takes fatty alcohol such as methanol, absolute ethyl alcohol, n-propanol, n-butanol, ethylene glycol and the like as a degradation reagent, and degrades the astragaloside IV in the medium formed by the fatty alcohol, tetrahydrofuran, dioxane, ethyl acetate, methyl tertiary butyl ether and other organic solvents to obtain the cycloastragaloside.

According to the invention, the aliphatic alcohol-organic solvent mixed solvent is selected as the degradation medium for preparing the cycloastragaloside from the astragaloside, the solubility of the astragaloside in the aliphatic alcohol is relatively high, and the selected organic solvent has a certain solubility for the astragaloside, so that the solubility of the astragaloside in the degradation medium is increased. Meanwhile, as the bisulfate is slightly dissolved in the fatty alcohol, the solubility of the solid acid in the degradation medium can be controlled by adjusting the composition or the proportion of the degradation medium, so that the hydrogen ion concentration and the catalytic capability of the degradation reaction are changed, and the degradation and the conversion of the astragaloside IV into the cycloastragaloside are facilitated. The degradation medium contains a large amount of fatty alcohol, the degradation is realized mainly by alcoholysis, the reaction is mild, and the excessive hydrolysis of astragaloside IV in the aqueous medium is avoided.

The reaction formula:

The specific operation steps comprise:

1) Selecting fatty alcohol and organic solvent to form astragaloside IV degradation medium, adding astragaloside IV and solid acid into the degradation medium, stirring in water bath at 50-90 ℃ for reaction, tracking the reaction by high performance liquid chromatography, and stopping the reaction after the astragaloside IV raw material completely disappears to obtain degradation liquid;

2) Cooling and filtering the obtained degradation liquid, neutralizing the filtrate with dilute alkali solution, removing the organic solvent, extracting the residue with an extractant, drying, removing the solvent to obtain crude cycloastragenol, and purifying by column chromatography to obtain high-purity cycloastragenol;

The solid acid is bisulfate.

The mass volume ratio of astragaloside IV to solid acid and degradation medium is 1g:10-100g:100-1000mL, preferably 1g:20-30g:250-500mL.

The content of fatty alcohol in the degradation medium is more than 10 percent.

The fatty alcohol is methanol, absolute ethyl alcohol, n-propanol, n-butanol or ethylene glycol; preferably methanol or absolute ethanol, preferably in the range of 30-50%.

The organic solvent is tetrahydrofuran, dioxane, ethyl acetate or methyl tertiary butyl ether, etc.

The solid acid is bisulfate, such as KHSO ₄、NaHSO₄、(NH₄)HSO₄, and the like, preferably sodium bisulfate, and plays a role of a catalyst.

The extractant used in the step (2) is ethyl acetate or dichloromethane.

In the step (2), the column chromatography purification is performed by taking 100-200 meshes of silica gel as a stationary phase and taking methylene dichloride-methanol mixed solution as a mobile phase; the volume ratio of dichloromethane to methanol is 19:1.

Compared with the prior art, the invention has the beneficial effects that:

the prior literature reports that the preparation of the cycloastragal is realized by hydrolyzing the glycosidic bond of astragaloside, but the method for preparing the cycloastragal by alcoholysis of the glycosidic bond of astragaloside is not reported.

Aiming at the defects of the common method for preparing the cycloastragal, the invention establishes a method for preparing the cycloastragal by degrading astragaloside IV in a fatty alcohol-organic solvent mixed medium by taking solid acid as a catalyst, and realizes the degradation reaction under mild conditions by changing the solubility of the catalyst in the medium, thereby avoiding the excessive reaction of the cycloastragal under severe conditions, improving the stability of the cycloastragal in the medium, and ensuring that the yield is more than 50 percent and the purity is more than 95 percent. The preparation method has simple steps and low cost, and is suitable for industrial production.

Drawings

FIG. 1 high performance liquid chromatography (HPLC-ELSD) of astragaloside IV degradation solution, purified cycloastragaloside and cycloastragaloside alcohol standard substance

FIG. 2 ¹ H NMR (DMSO-d 6) spectrum of cycloastragenol

DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION

The technical scheme of the invention is further described in detail through specific embodiments. These examples are not intended to limit the scope of the invention.

Example 1

To a mixed medium of 150mL of methanol and 150mL of tetrahydrofuran, 1g of astragaloside IV with the purity of 98%, 25g of sodium bisulfate are added, and in a water bath at 60 ℃, stirring reaction is carried out for 20 hours, cooling and filtering are carried out, the obtained filtrate is neutralized by dilute alkali solution, organic solvent is removed by rotary evaporation, water is added to 100mL, then the mixture is extracted three times by using ethyl acetate with the same volume, ethyl acetate is combined, and the mixture is dried by using anhydrous sodium sulfate. Removing ethyl acetate by rotary evaporation to obtain crude cycloastragenol. And then using 100-200 mesh silica gel as stationary phase, and using 19:1 dichloromethane-methanol mixed solution as mobile phase to make column chromatography purification so as to obtain 0.33g of cycloastragenol, its yield is 52.7% and purity is 97.5%.

Example 2

To a mixed medium of 50mL of ethylene glycol and 200mL of ethyl acetate, 1g of astragaloside IV with a purity of 85% and 20g of potassium bisulfate were added, and the mixture was stirred in a water bath at 90℃to react for 12 hours, cooled and filtered. The filtrate was neutralized with a dilute alkali solution, and 50mL of distilled water was added thereto, and the mixture was separated by a separating funnel, and the aqueous phase was extracted three times with 100mL of ethyl acetate, and the ethyl acetate was combined and dried over anhydrous sodium sulfate. Removing ethyl acetate by rotary evaporation to obtain crude cycloastragenol. And then using 100-200 mesh silica gel as stationary phase, and using 19:1 dichloromethane-methanol mixed solution as mobile phase to make column chromatography purification so as to obtain 0.28g of cycloastragenol, its yield is 50.5% and purity is 95.6%.

Example 3

1G of astragaloside with the purity of 98% and 20g of ammonium bisulfate are added into a mixed medium of 150mL of absolute ethyl alcohol and 150mL of dioxane, and the mixture is stirred and reacted for 16 hours in a water bath with the temperature of 80 ℃, cooled and filtered to obtain filtrate, the filtrate is neutralized by dilute alkali solution, organic solvent is removed by rotary evaporation, water is added to 150mL, the mixture is extracted three times by using ethyl acetate with the same volume, and the ethyl acetate is combined and dried by using absolute sodium sulfate. Removing ethyl acetate by rotary evaporation to obtain crude cycloastragenol. And then using 100-200 mesh silica gel as stationary phase, and using 19:1 dichloromethane-methanol mixed solution as mobile phase to make column chromatography purification so as to obtain 0.34g of cycloastragenol, its yield is 54.9% and purity is 98.5%.

Example 4

To a mixed medium of 400mL of methanol and 100mL of methyl tertiary butyl ether, 1g of astragaloside with the purity of 98%, 30g of sodium bisulfate are added, and in a water bath at 60 ℃, stirring reaction is carried out for 24 hours, cooling and filtering are carried out, the obtained filtrate is neutralized by dilute alkali solution, organic solvent is removed by rotary evaporation, water is added to 150mL, then the mixture is extracted three times by using ethyl acetate with the same volume, and the ethyl acetate is combined and dried by using anhydrous sodium sulfate. Removing ethyl acetate by rotary evaporation to obtain crude cycloastragenol. And then using 100-200 mesh silica gel as stationary phase, and using 19:1 dichloromethane-methanol mixed solution as mobile phase to make column chromatography purification so as to obtain 0.31g of cycloastragenol, its yield is 50.2% and purity is 98.8%.

Claims

1. A method for preparing cycloastragaloside by degrading astragaloside IV, which is characterized by comprising the following steps:

The fatty alcohol is methanol, absolute ethyl alcohol or glycol, and the content of the fatty alcohol in the degradation medium is 30-50%; the organic solvent is tetrahydrofuran, dioxane, ethyl acetate or methyl tertiary butyl ether;

the solid acid is bisulfate: sodium bisulfate, potassium bisulfate and ammonium bisulfate;

The mass volume ratio of the astragaloside IV, the solid acid and the degradation medium is 1g:10-100g:100-1000mL.

2. The method for preparing cycloastragaloside by degradation of astragaloside according to claim 1, wherein the mass-volume ratio of astragaloside to solid acid to degradation medium is 1g:20-30g:250-500ml.

3. The method for preparing cyclic astragalus alcohol by degradation of astragaloside according to claim 1 or 2, wherein the extractant used in the step (2) is ethyl acetate or methylene chloride.

4. The method for preparing cyclic astragalus alcohol by degradation of astragaloside IV according to claim 1 or 2, wherein the column chromatography purification in the step (2) is performed by using 100-200 mesh silica gel as a stationary phase and methylene chloride-methanol mixed solution as a mobile phase.

5. The method for preparing cycloastragaloside by degradation according to claim 4, wherein the volume ratio of dichloromethane-methanol is 19:1.