BG65997B1 - Method for silybinin preparation - Google Patents

Abstract

The method is used for the preparation of pure silybinin not containing isosilybinin out of dry extract of the fruit of Silybum marianum. The turned out product is used as a means for the prophylaxisand treatment of diseases of the liver, including grave toxic impairments and as an initial substance for the preparation of hydrophilic and lipophilic silybinin derivatives applicable in medical practice as antidote in cases of acute poisonings and chronic liver damages. By the method more lower-quality initial substances can also be treated, both in respect of the silymarine, as well as in relation to any increased admixture content such as tanners, fat in oils, and others. The yield and the quality of the technical quality silybin is increased, the reaction time is being considerably decreased and the processes run in a simpler manner. The yield and the quality of the final product of silybinin are also increased. The parent lyes produced after the deleaching of the technical quality silybin can be treated to producing an useful product by means of which, using an ecological means, the waste containing organic solvent is being eliminated.

Description

Technical field

The invention relates to a method for the preparation of pure silybinin, free of isosilibinin, from a dry extract of the fruits of Silybum marianum L. (thorn), which will be used as a tool for the prevention and treatment of liver diseases and serious toxic liver damage and as a starting material for the preparation of hydrophilic and lipophilic derivatives of silybinin, which have found application in medical practice as an antidote for acute poisoning and chronic liver lesions.

BACKGROUND OF THE INVENTION

The hepatoprotective activity of Silybum marianum L fruits is known to be due to flavolignans. The main component Silibin, also known as Silymarin 1, was isolated by R. Munster as early as 1966.

Silibinin, the main component of the mixture, is benzodioxane, which is a mixture of two diastereoisomers in a ratio of 1: 1 (7R, 8R and 7S, 8S). The other components of silymarin are silidianin, silicristin, taxifolin, and a total of 12 compounds, according to latest data / B. A. Kurkin, “Chemical Pharmaceutical Journal” Vol. 37, No. 4, 2003 /.

O-.0H ~ o _o ^ _oh * he

HE 0

Silybinin

OMe ⁰ S he but _{0 about} CH.OH ^ he

HE ON

Imylibkiin

There are two variants of a method for the preparation of pure silybinin free of isosilibinin [GB 2167746].

According to the first embodiment, a dry extract of Silybum marianum L. containing about 70% polyhydroxy-phenylchromanonosulfonyl-Silymarin Ι-IV is suspended in 3-5 times methanol, heated to reflux. Under reduced pressure, 1/3 to 2/3 of methanol is removed, the resulting suspension is left at room temperature for 10 to 28 days, the resulting precipitate is washed with methanol and dried. The dry product - technical silybinin - was dissolved in 40-60 times ethyl acetate, treated with activated carbon, after filtration, the filtrate was evaporated to 1/10 of the original volume, methanol was added and allowed to stand at room temperature for several hours at room temperature. vigorous stirring, the resulting precipitate was filtered off in vacuo, washed with ethyl acetate, dried in vacuo.

According to the second variant, Silymarin I-IV is suspended in water-saturated ethyl acetate and allowed to stand for 1-2 days, after filtration it is washed with cold water-saturated ethyl acetate, dried in vacuo at 30-50 ° C, the obtained dry product dissolved in anhydrous ethyl acetate at reflux temperature, the solution was treated with reflux, filtered, concentrated in vacuo, ethyl acetate added, left for 5 to 10 hours, the resulting precipitate filtered, suspended twice in ethyl acetate , pre-dried at 40 ° C for 1 h Output 24 h in vacuo and then doizsushava under vacuum for 48 h at 40 ° C.

A yield of 79 to 85%, calculated on the silybinin content of the technical crude silybinin, is obtained with a purity of 96 to 98%.

As the description shows, these two variants of the method are too long. In addition, the starting substance must have a fairly high silymarin I-IV content.

The problems to be solved are: achieving high yields of silybinin with high purity using a starting material with a lower silybinin content, reducing the duration and simplifying the extraction processes.

65997 Bl

SUMMARY OF THE INVENTION

These problems are solved by the method of the present invention, which is as follows.

Substance dry extract of Silybum marianum L is treated with heating and stirring with 4- to 6-fold amount of 70 to 98% ethanol, after standing for up to 24 hours the precipitated product is filtered off, washed with cooled ethanol, and dried in vacuo . Technical silybinin is obtained in a yield of not less than 80% and a silybinin content of not less than 90% determined by HPLC.

The next purification step is carried out in two equivalent variants - with a solvent ethanol or with a solvent mixture of ethyl acetate.

In the first embodiment, the technical silybinin is dissolved at reflux temperature and stirred in 50- to 60-fold ethanol, activated carbon is added, the filtrate is concentrated, the precipitate is filtered off, washed with cooled ethanol and dried in vacuo . A product of at least 98% silibinin content is obtained in 85% yield with respect to the technical silybinin input.

In the second embodiment, the technical silybinin is crystallized from a 40-60 fold amount of ethyl acetate-ethanol mixture. The use of ethyl acetate alone to purify the technical silybinin obtained according to the invention (analogous to the known method) is technically unacceptable. Optimal dissolution is achieved only with ethyl acetate-ethanol mixture. Activated charcoal was added, filtered, the filtrate was concentrated, ethanol was added to the concentrate, after standing for 6 to 12 hours at room temperature, the precipitated silobinin was filtered off, washed with cooled ethyl acetate and dried in vacuo. A product containing not less than 98% silibinin is obtained in a yield of 90% relative to the technical silybinin input.

The method according to the present invention allows the use of a lower substance starting material of at least 65% silymarin, i. allows the processing of lower quality starting materials, both with regard to the total mixture of hydroxyphenyl chromanones - silymarin, and with regard to the increased content of impurities such as tannins, fatty oils and more. The yield and quality of technical silybinin is increased. The reaction time to obtain technical silybinin is dramatically shortened. The processes are greatly simplified. The yield and quality of the final product silibinin is increased.

Surprisingly, the method according to the invention allows the utilization of the mother liquors obtained after the removal of technical silybinin. They can be processed in a known manner to produce a product with a total flavolignol content of not less than 65%, depleted of silybinin and enriched in silidianin, silicristin and isosilibinin. This product can be used, for example, by being included in food supplements, veterinary preparations, and tested for new uses. In this way, an environmentally sustainable elimination of a waste containing an organic solvent is achieved.

Embodiments of the invention

Example 1. Preparation of technical silybinin

100 g of dry extract of Silybum marianum containing 65% silymarin are suspended in 500 ml (442.7 g) of 70% ethanol. The mixture was stirred at reflux for 15 minutes. After standing for 24 hours, the precipitated product, technical silybinin, was filtered, washed twice with 25 ml of cooled 70% en ethanol twice and dried in vacuo. Yield of technical silybinin - 80% over the silybinin content of the starting material, with silybinin content of 90%.

Example 2. Purification of technical silybinin g Technical silybinin obtained according to example 1 was dissolved in 600 ml (540 g) of ethanol under heating and stirring. 3.6 g of activated carbon were added and stirring was continued at reflux for 2 h with reflux turned on. The solution was filtered and concentrated to 50 ml. Stays for 24 hours at room temperature. A crystalline precipitate precipitates and is washed twice with 20 ml each

65997 B1 chilled ethanol and dried in vacuo at a temperature not higher than 40 ° C. A product with a silybinin content of 98.2% and a yield of 87% with respect to the technical silybinin input was obtained. 5

Example 3. Purification of technical silybinin

To 12 g of technical silybinin prepared according to Example 1 was added 600 ml of ethyl acetate under reflux and stirring, and absolute ethanol was added dropwise up to 1/20 of volume. 3.6 g of activated carbon were added and stirring was continued for 2 h at reflux. The solution was filtered and concentrated to 50 ml. On distillation, the ethanol is azeotropically separated with ethyl acetate. To the concentrate was added 5 ml of absolute ethanol. Stays for 12 hours at room temperature. The crystalline precipitate was filtered off, washed twice with 10 ml of cooled ethyl acetate and dried in vacuo at a temperature not higher than 40 ° C. The product obtained has a silybinin content of 98% in a yield of 90% in terms of the amount of technical silybinin employed.

Example 4.

The mother liquors separated on the preparation of technical silybinin were concentrated to 1/3 of the volume and the concentrate was dropped into 10x 3% sodium chloride solution at room temperature and stirring. After standing, the precipitated product is filtered off and washed with distilled water. Dry at a temperature not higher than 60 ° C. The product obtained is a mixture of flavonolignans with a content of more than 65% enriched in silidianin, silicristin and taxifolin and the like. and impoverished with respect to silybinin content. Secondary silymarin yield - 50-60% of the starting amount of the substance dry extract of Silybum marianum.

Claims (2)

1. A method for producing pure isosilibinin-free silibinin by extracting technical silybinin from a standard substance dry extract of Silybum marianum with a polar organic solvent, purification of the obtained dry technical silybin by recrystallization from an organic solvent, activated carbon treatment, activated carbon treatment concentration, washing and drying, characterized in that the extraction of technical silybin is carried out with 4- to 6-fold amount of 70 to 98% en ethanol, and after the solution has been left standing for about 24 hours, the resultant The filter cake is filtered, washed with cooled ethanol and dried, and then the resulting dry technical silybinin is dissolved in 40-60 times ethanol or ethyl acetate containing boiling water and after treatment with activated carbon, filtration and concentration, the resulting precipitate washed with cooled ethyl acetate or ethanol and dried in vacuo. 2. A process for the preparation of pure, isosilibinin-free, silybinin according to claim 1, characterized in that after the dissolution of technical silybinin in ethyl acetate containing ethanol, after treatment with activated charcoal, filtration and concentration, additional ethanol is added, and after standing for 6 to 12 hours at room temperature, the resulting precipitate was washed with cooled ethyl acetate and dried in vacuo.