SI8511786A8 - Process for preparation of derivatives of sylibinine - Google Patents

Description

A technical problem

There is a need to prepare novel silibi nin derivatives which, by their properties, in particular water solubility, will outperform related compounds known in the art.

The state of the art

Mary's osat - Silybum marianum (L.) Gaertn. (Carduus marianus L.) - is a medicinal plant that has been known since ancient times. Of the flavolignans found in the fruits of this plant, R.Munster isolated one component, silibin, cf. R.Munster dissertation, Miinchen, 1 966. The chemical structure of this compound was explained by A.Pelter and R.Hansel, cf. Tetrahedron Letters. London, Volume 25, p. 2911-2916 (1968).

Silibin is known to have previously been called silymarin I, a valuable medicine for the liver, cf. DE-AS

67 666. The technical process for the preparation of silibin (silymarin I) is e.g. described in DE-AS 19 23 082.

As early as 1974, two positional isomers, namely silibin and isosilibin, were assumed by H Wagner, P.Diesel, and M.Seitz, Arzneimi11e 1forschung, Volume 24 (4), pages 466-471. This assumption was refined and experimentally confirmed by A.Arnone, L.Merlini and A.Zanarotti, Journal Chemical

Society Chem.comm., 1979, Volume 16, p. 696/97. Therefore, the known silybin consists of two different compounds, namely compounds of the following structural formulas A and B:

(A) si 1i binin

(B) isosilibin

It is apparent from these structural formulas that these compounds are positional isomers. The compound of formula (A) has recently been labeled with the silibinin INN. We will henceforth use this designation in the present application for a compound of formula (A).

The therapeutic use of silibin was aggravated by the fact that silibin was practically insoluble in water, so that no solutions or preparations containing silibin requiring a certain solubility in water could be prepared.

DE-PS 19 63 318 describes silibin derivatives having a certain solubility in water, but this is a very complex mixture of succinic acid polyesters. This mixture is so complex because it contains in the silybin five esterable hydroxyl groups, except that silybin contains both of the above-mentioned position isomers and succinic acid used for esterification is dicarboxylic acid, which can thus form monoesters as well as diesters. However, for pharmaceutical purposes, a product consisting of an unprecedented number of a wide variety of unexplained compounds is not useful.

Description of solution to a technical problem with implementation examples

It is therefore an object of the invention to prepare, for pharmaceutical purposes, suitable water-soluble silibinin derivatives, which are accurately characterized as chemical individuals.

We have now found that silybinin derivatives of certain alkane- and alkylenedicarboxylic acids meet these requirements.

The subject of the invention are therefore silybinin derivatives of general formula I

where n + tn are each independently 0 or 1, respectively, are Alk ^ and Alk ^ independently of each other an alkylene residue having 1 to 4 carbon atoms or an alkenylene residue having 2 to 4 carbon atoms and respectively

M ₁ and each independently from each other a hydrogen atom or an alkali metal atom.

Preferred compounds of formula (I) are compounds wherein n and m are each independently 0 or 1, Alk ^ and Alk ^ each represent an alkylene residue with 2 carbon atoms, and and M? in each case independently of one another, an alkali metal atom. Preferably n and ra, Alk ₁ and Alk ^ and M ₁ and M ,, each have the same meanings.

Particularly preferred is silibinin-C-2 ', 3-dihydrogensuccinate, disodium salt.

For the compounds of the invention, OH silibinin groups that are not bound to the benzene core are partially or fully esterified, e.g. with oxalic acid, malonic acid, succinic acid, adipic acid, nonaleic acid or fumaric acid.

Preferably, both non-aromatically bound OH silibinin groups are singly esterified with one of said carboxylic acids.

The process of the invention for the preparation of silibinin derivatives for which patent protection is claimed is characterized in that about 1 mass fraction of silibinin of formula (A)

(A) Silybinin is dissolved in a compound of 1 formula up to 2 parts by weight of pyridine and while stirring before 3 parts by weight of dicarboxylic acid anhydride *

where Alk stands for one of the residues Alk and Alk ₂ defined above, then ethanol is added until a homogeneous mixture is formed, then water is slowly added under intense stirring, with the present esters of the aromatic-bound OH groups hydrolyzed as soon as this hydrolysis is complete, is diluted with ethyl acetate, washed with acidic water, saturated with ethyl acetate, the ethyl acetate phase is evaporated, taken up in ethanol, and the alcoholic solution of alkali hydroxide is converted into a salt of a free, non-esterified carboxylic acid residue.

Preferably, the reaction is carried out with dicarboxylic acid anhydride at 40 to 50 ° C. The pH with ethyl acetate of saturated acidic rinsing water is maintained preferably at about 1.5 to 2.4.

These compounds, in particular the compound silibinin-C-2 ', 3-dihydrogensuccinate, disodium salt, show a surprisingly pronounced pharmacological effect in the treatment of burn injuries. Furthermore, it retains the full pharmacological efficacy of the known silibin as a liver drug, despite the derivatization described above. They are especially suitable for the treatment of liver cirrhosis and toxic-metabolic liver damage.

Surprisingly, the compounds of the invention have also proven to be extremely effective in treating mushroom poisoning, especially the very dangerous fly poisoning (Amanita phalloides). Even poisoning with halogenated organic solvents, such as carbon tetrachloride, trichloroethylene, chloroform, etc., can be surprisingly well treated. Preventive use prevents the compounds of the invention from the damage described above.

The subject of the invention are therefore also medicaments containing these compounds. They are mostly used systemically, e.g. in the form of pills, capsules, solutions, in conventional carriers and optionally together with conventional excipients. The daily dose for an adult human is about 50 to 500 mg depending on the patient's condition and the severity of the disease symptoms.

Experiments with si1ibini n-C-2 ', 3-dihydrogensuccinate, disodium salt (si 1i-suc-na).

Symptoms of burns are mainly caused by intoxication with thermal tissue necrosis products. They have proven that they are responsible for the auto-intoxication processes after severe skin burns, in a variety of ways. Particularly convincing are the transplantations of burned and unburnt skin on healthy or burned recipient animals, showing that non-burned burned skin recipients die, whereas no burns have been observed in healthy recipient healthy skin, see K.H. Schmidt et al., Neuere

Aspects of zur Autointoxikation nach schweren Verbrennungen;

Die Verbrennungskrankheit (F.W. Ahnefeld et al., Eds. L),

Springer, Berlin 1982, p. 45-52.

Skin burns result in the release or formation of many chemical compounds. Despite their abundance, it has been fortunate to explain the structure of some of these compounds.

Among other things, they have been able to demonstrate that skin burns produce compounds similar to those produced

...... And in lipid peroxidation. There are also analogies regarding the toxic effects of these substances. Particularly important is the formation of toxic effect saturated and unsaturated aldehydes with different long chains as a result of lipid peroxidation. (Benedetti et al., Identification of 4-hydroxynonenal as a cytotoxic product originating from the peroxidation of liver microsomal lipids, Biochim.Biophys.Acta 620, 281-296, 1980) and thermal tissue damage (KH Schmidt et al., Studies on the structure and biological effects of pyrotoxins purified from burned skin, World J. Surg. 3,

361-365, 1979). Therefore, they are thought to lead to burns leading to oxidative damage to cellular structures.

Therefore, they have investigated the auto-oxidative changes of membrane lipids as a result of auto-intoxication after severe burns. In particular, changes in the fatty acid composition of membrane lipids were investigated. They further tested the effect of silibinin derivatives of the invention on changes in the fatty acid composition of membrane lipids.

Changes in fatty acid composition of membrane lipids after severe burns

Wistar male rats with an average weight of 360 g were bred in groups of three with free access to water and dry food. At the start of the experiment, the room temperature was 22 ° C, after the experiment began the animals were at 30 ° C.

Skin burns were caused by a copper seal with an area of 20 cm ² at constant pressure and temperature of 250 ° C. To exclude thermal damage to the deeper organs, we pulled the skin over an air-cooled hollow spatula. With this animal model, very exact burn injuries can be caused that give constant survival rates.

Prior to the start of the experiment, animals were given anesthesia with 50 mg / kg nembutal. After the burn, we injected i.p. to prevent shock 20 ml of Ringer's lactate solution.

We formed 5 experimental groups:

a) Normal group: completely intact animals

b) control group I: only 6-day silibinin treatment with 75.5 mg silisucine.

c) Control group H: Apparently operated animals

d) Toasted group: 25%, 250 ° C, sec, 0.49 bar

e) Test group: Animals given 6 days starting one day before burn, 75.5 mg 'force-suc-na i.p.

To isolate the microsomes, blood was released to the anesthetized animals at the end of the experimental period. The livers were then removed, weighed and immediately transferred to ice-cold isolation medium (0.25 m sucrose, 1 mM EDTA, 10 mMol Tris. HCl, pH 7.2). The livers were dissected and homogenized in the medium. Differential centrifugation allowed the microsomal fraction to be lettered. The microsomes were resuspended and centrifuged again. A suspension was then prepared in which ml of the suspension corresponded to 1 g of liver tissue.

Lipids were determined by J. Folch (A simple method for the isolation and purification of total lipids from animal tissues, J. Biol. Chem. 226, 497-508 (1957)) »Bligh and Dyer modification (A rapid method of total lipid extraction and purification, Can. J. Biochem. Physiol. 37, 911-917 (1959).

The extracted microsomal lipids were washed with sodium hydroxide solution. The free fatty acids were esterified by the addition of BF ^ -methanol. After evaporation of the methanol and removal of the hydrophilic by-products, the fatty acid esters were quantified.

No significant changes in the fatty acid pattern were found in non-caring groups of animals. Thus, narcosis and minor surgery did not lead to alteration of microsomal lipids. For this reason, the normal group and the control group were combined into one control group for further comparisons.

Comparisons of non-baked and burned animals with respect to their microsomal fatty acid pattern revealed aggravating shifts from unsaturated to saturated fatty acids.

Figure 1 shows the distribution of fatty acids in microsomal lipid livers and due to thermal damage to the skin induced changes. The proportion of palmitic acid (C16) after burning increases from 25.1 to 34.4% of total fatty acids. For stearic acid (C18), the proportion in burned animals is 46.3% to 13.2% above the values obtained in control animals. In oil saliva (C18: 1), it can be shown to be slight, non-significant

1 reduction. The proportion of linoleic acid (C18: 2) decreased to about 1/3 of the initial value after burning.

With arachidonic acid (C20: 4), only 31% of the initial content was finally found after burning.

The following Table I shows the effect of sily-suc on the fatty acid content of burned and uncured animals.

Table_1_

Fatty acids of rat liver microsomal lipid fatty acids after emergency treatment in burned and non-burned animals

Cl 6 C1 8 C1 8: 1 C1 8: 2 C20: 4 Neopecene 29,8 % 37,2 % 8.9% 9,6% 16.2 % (control 2 + 12.3 + 1, 1 ± 3.3 ± 4.9 group I) Toasted 25,4 % 37.5 % 7,8% 11,4% 18,0 % _ + 6.0 . + 8.6 ± 1, θ ± 5,3 ± .9,1

Treatment with the silibinin derivative of the invention in non-infected control animals has been shown to show no significant change compared to untreated animals. In burned animals, treatment leads to complete elimination of the loss of unsaturated fatty acids.

In summary, the following may be noted: burns lead to a change in the fatty acid pattern of microsomal lipids. This is thought to be caused by oxidative damage to the membranes. This is especially evident in the strong reduction of polyunsaturated fatty acids.

The silibinin derivatives used in the invention are, however, capable of inhibiting oxidative cell damage. Therefore, they are particularly suitable to break through the mechanisms of oxidative damage after severe burns.

As previously described, it is believed that they lead to autotoxic reactions after severe burns, especially to oxidative cell damage. Therefore, we investigated the impact of standardized thermal injury on PHA-induced blastogenesis

T-lymphocytes from the spleen and peripheral blood of rats. We further investigated the effect of silibinin derivatives of the invention on such disorders of lymphocytic function after severe burns.

Effect of standardized thermal injury on PHA-induced blastogenesis of T-lymphocytes from rat spleen and peripheral blood

As described above, we burned the skin on the back of a Wistar rat with a copper stamp. The control group was served by apparently burned animals, on which we performed all the operative manipulations without being burned. After 2, 4, 7 and 9 days, we burned, respectively. control animals were deprived of blood and spleen in ether narcosis.

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To isolate the lymphocytes, Ficoll-Hypa'que solution (density 1,077) was coated with heparinized blood.

We then centrifuged and tested the lymphocytes obtained for their viability with trypan blue. To isolate the spleen lymphocytes, the organ was crushed, passaged through a sieve, and the accompanying erythrocytes were removed with lysis solution after Gay.

The cell mixture was then incubated for 30 minutes in a vessel in the presence of 5% heat-inactivated fetal calf serum to reduce the proportion of mononuclear cells in suspension by adhesion to the wall of the vessel (5%). For cultivation, cells were placed in flat-bottom microtiter plates. 20% fetal calf serum was then added. In this way, spontaneous blastogenesis was determined by measuring the incorporation of ⁸ H-thymidine- (2Ci / mM) into the DNA of the cells.

In the experiments, we clarified that optimal mitogen stimulation is performed at a PHA (mitogenic phythemagglutinin) concentration of 5 mg / ml. In these experiments to optimize the cellular test system, we further found that maximal stimulation of new DNA synthesis was performed after 72 hours. We further found that, in order to achieve maximum stimulation, the optimal fetal calf serum concentration at

%.

As described above, spontaneous blast3 genesis was determined by measuring the incorporation of H-thymidine into the DNA of cells. Ce3 cheeks were collected 18 hours after H-thymidine supplementation, with the zero point coinciding with the moment of maximal stimulation for 18 hours.

By investigating the effect of silibinin derivatives used in the invention, a group of rats was treated with a silibinin derivative. For this purpose, 75.5 mg of force-suc-once daily was injected intraperitoneally. This therapy was performed from the day of the burn to the day of the organ removal (max.

on).

A stimulation index was calculated to evaluate the results obtained in control animals and non-infected animals and in silisuc-treated animals. This numerical value represents the quotient of the mean of the stimulated sample and the mean of the control sample. From the stimulation index thus obtained for each experimental animal, the mean stimulation index for the animal group was calculated. The results obtained are expressed by this SI index.

Figure 2 shows the effect of the applied force-suc-on on lymphocyte blastogenesis. In burned animals, silibinin clearly increased the reduced ability to stimulate cells.

For the second day, the response of blood lymphocytes to PHA was shown to be 10-fold greater in animals treated with force-suc-na. At day 4 post-traumatic, the value of the stimulation index in blood lymphocytes for treated animals was 8, while the corresponding value in untreated animals was 1.5.

In spleen cells, the stimulation indices of burned, untreated animals are all clearly below 1. Administration of silibinin leads to a significant improvement on all investigated days, reaching a maximum on the 7th post-traumatic day.

Comparative experiments were also performed to show that force-suc-alone alone in healthy animals did not lead to any significant changes in the stimulation ability of PHA-induced blastogenesis.

T-lymphocytes from the spleen and from the peripheral blood.

Accordingly, the silibinin used in the invention significantly stimulates blastogenesis of burned animal lymphocytes.

We further found that the general catabolism was lower in animals treated with silibinin derivatives because animals quickly regained weight after thermal injury.

Mushroom poisoning

Fly poisoning is considered to be one of the most difficult for medicine to know. Although only 10 to 30% of all mushroom poisoning causes green flies, the government has always been of the greatest medical interest to poison this mushroom because of its risk.

In older publications, mortality rates are from 30 to

%. Thanks to modern intensive medicine, according to a summary study by FLOERSHEIM et al. in 205 patients, this number decreased to an average of 22.4%.

The fly poison, amanitine, can be deadly for an adult at 7 mg. This amount of poison is found in about 50 g of fresh specimen.

Following a series of promising animal experiments, the active ingredient sili-suc-na was included in the treatment of fly poisoning.

In addition to the usual therapeutic measures, patients with fly poisoning were treated with force-sucna. Of these 28 patients, only one died with the suicide intent of increasing the amount of toxic mushroom. This result shows tremendous therapeutic advances in the field.

Preparation of isosilibin-free silibinin

Suspension of 500 g of product according to DE-AS 19 23 082,

Column 8, species 14 to 19, having silymarin content of about 70% at the isomer ratio si 1 ib and / si1idianin / si1ikris ti n

3: 1: 1, wherein silibin contains about 1/3 of isosilibin, and kg of methanol = 2.53 1 is heated while stirring for 15 minutes until boiling. Some silibinin may already be eliminated from the solution thus obtained. Then, 0.75 to 1.25 kg = O, 96 to 1.58 l of methanol are removed in vacuo and the residue is left to stand at room temperature for 10 to 28 days. The silibinin recovered is filtered off and washed twice with 50 ml of cold methanol each. After drying at 40 ° C, the isolated crude silibinin is purified in vacuo as follows:

g of crude silibinin is dissolved while heating in 3 l of technical ethyl acetate. Then 20 g of activated charcoal was added and stirred for 2 hours under reflux conditions. The clear was then filtered and the solution was evaporated at 50 ° C under reduced pressure to about 250 ml. The concentrate was stirred for 15 minutes using an Ultra-Turrax apparatus and 25 ml of methanol was added while stirring. The mixture was then allowed to stand overnight at room temperature. Before draining the silibin extracted therein, the mixture is stirred again for 5 minutes, also using an UltraTurrax apparatus. The aspirated precipitate was washed twice more with 50 ml of ethyl acetate and dried in a vacuum oven overnight at 40 ° C. The product was then ground and dried under the same conditions for a further 48 hours.

EXAMPLE 1

Preparation of silibinin-C-P ', 3-dihydrogensuccinate

g of silybinin is dissolved at 45 ° C in 70 ml of pyridine, 50 g of succinic anhydride are added, the mixture is stirred for about 8 hours at 45 ° C, 30 ml of ethanol are added and stirred until a homogeneous mixture is formed. Then, during vigorous stirring for about 30 minutes, 60 ml of water was added to soothe the phenyl esters. After stirring at 30 ° C for about 1 hour, the phenyl esters were quantitatively hydrolyzed. The hydrolysis completeness is verified by HPLC. The hydrolysis is stopped by the addition of the resulting reaction mixture to the fast 1.7 l of acetic acid ethyl ester.

To separate excess succinic acid and pyridine, extract the reaction solution diluted with acetic acid ethyl ester, countercurrently with 5 l of water each, saturated with acetic acid ethyl ester and have a pH of 1.85 (adjusted with dilute aqueous hydrochloric acid). Acetic acid ethyl ester is then pumped into saturated, acidified rinsing water in a circular flow toward the diluted reaction solution and then maintained with the addition of dilute hydrochloric acid at 1.85 until this pH remains constant after the transition of the acetic acid ethyl ester.

To wash off the excess hydrochloric acid then, the ethyl acetate phase is extracted twice counter-current with 3.4 l of water saturated with acetic acid ethyl ester. As soon as the pH of the rinse water is greater than 4.5, the organic phase is quantitatively separated, evaporated under vacuum at 40 to 50 ° C to 1/12 of an output volume of 0.2 l) and diluted with 125 ml of ethanol.

The title compound is obtained by ethanol / water conversion and drying at 50 DEG C. under vacuum for 15 hours.

To prepare the assay sample, the title compound was rewrote three times from ethanol / water and then dried for 15 hours at 50 ° C in vacuo.

A molecular peak occurs at the expected molar mass of 682 in the FD mass spectrum.

The IR spectrum shows two overlapping bands in the frequency range of C0, and, as in silibinin, belongs to one carbonyl function of the pyron ring at a wavelength of 1635 cm ^-1 . The second band lies at 1730 cm and originates from both estercarbonyl functions.

^{The 1} H-NMR spectrum confirmed that double esterification had taken place. Thus, the integration ratio of aromatic protons to methylene protons of succinic acid residues is 8: 8 (ppm range 5.9 - 7.1). The ratio of these methylene protons (ppm 2.6) to the methyl protons of the methoxy group (ppm 3.8) is 8: 3 and is therefore in agreement.

3

Also, chemical shifts in C investigations indicate that esterification was carried out on both alcohol OH groups, since chemical shifts change most strongly at and adjacent carbon atoms - C as well as at C ₂ to ^C 4 '

Elemental analysis for C ^ H ^ O ^ (682,60)

C H 0 Calc .: 58.07 4,43 37,50 Found: 58.05 4,57 37, 31

EXAMPLE 2

Preparation of silibinin-C-23-dihydrogensuccinate, disodium salt

COfc

The ethanol solution obtained according to Example 1 was added dropwise during stirring and external cooling at -5 to 9 ° C an amount of 6% ethanol sodium hydroxide, determined by determining the solids content of the above solution, stirring the suspension for another hour at room temperature. , the extracted beige solid is sucked off, suspended twice after 5 to 10 min. using Turrax in 150 ml of ethanol and suction again. To remove the remaining acetic acid ethyl ester, the product was then suspended for 14 hours at room temperature in 280 ml of ethanol, filtered off with suction, washed with 70 ml of ethanol and dried for 15 hours at 40 to 45 ° C in a vacuum oven. The dried product is then milled, sieved to a grain size of less than 0.2 mm and dried for a further 48 hours at 40 to 45 ° in vacuo. This gave 52 g of the title compound (96% yield).

The title compound has no sharp melting point. In about 80 ⁰ shall be sintered and with the formation of bubbles of melting at about 100 ° C.

The UV spectrum in methanol shows λ = 288 nm, £, = 1.73 max io ⁴ .

The molar mass of the title compound is 726.56. The compound is a slight beige, microcrystalline powder with no special odor and salty taste. It is easily soluble in water, hardly soluble in ethanol and practically insoluble in acetone, ether and chloroform.

Use case

Preparation of lyophilizates for i.v. giving

Silibinin-C-2 ', 3-dihydrogensuccinate, disodium salt 75.0 mg mani t 10.0 mg water for injections ad 1.5 ml

Fill 1.5 ml of the solution into spear-shaped ampoules holding 5 ml ^ and then lyophilize them by known technique. The finished lyophilisate ampoule is sealed for normal storage.

For use, dissolve the lyophilisate in 5 ml of sterile saline solution.

An indication of the best known applicant for the economic exploitation of the object of the invention

Preparation of silibinin-C-S ', 3-dihydrogensuccinate

HO

g of silybinin is dissolved at 45 ° C in 70 ml of pyridine, 50 g of succinic anhydride are added, the mixture is stirred for about 8 hours at 45 ° C, 30 ml of ethanol are added and stirred until a homogeneous mixture is formed. Then, during intense stirring for about 30 minutes, 60 ml of water was added to soothe the phenyl w O esters. After stirring at 30 C for 1 hour, the phenyl esters were quantitated. The hydrolysis completeness is verified by HPLC. The hydrolysis is stopped by the addition of the resulting 1.7 mL ethyl acetic acid ethyl ester rapidly.

To separate excess succinic acid and pyridine, extract the reaction solution diluted with acetic acid ethyl ester, countercurrently with 5 l of water each, saturated with acetic acid ethyl ester and have a pH of 1.85 (adjusted with dilute aqueous hydrochloric acid). Acetic acid ethyl ester is then pumped into saturated, acidified rinsing water in a circular flow toward the diluted reaction solution and then maintained with the addition of dilute hydrochloric acid at 1.85 until this pH remains constant after the transition of the acetic acid ethyl ester.

To wash off the excess hydrochloric acid then, the ethyl acetate phase is extracted twice counter-current with 3> 4 l of water saturated with acetic acid ethyl ester. As soon as the pH of the rinse water is greater than 4.5, the organic phase is quantitatively separated, evaporated under vacuum at 40 to 50 ° C to 1/12 of an output volume of 0.2 l) and diluted with 125 ml of ethanol.

The title compound is obtained by ethanol / water conversion and drying at 50 DEG C. under vacuum for 15 hours.

To prepare the assay sample, the title compound was rewrote three times from ethanol / water and then dried for 15 hours at 50 ° C in vacuo.

A molecular peak occurs at the expected molar mass of 682 in the FD mass spectrum.

The IR spectrum shows two overlapping bands in the valence frequency range of C0, and, as in silibinin, one carbonyl function of the pyrone ring at a wavelength of 1635 cm belongs to the second band. It lies at 1 730 cm ^-1 and originates from both. 1-function ester carbones.

The 1 H-NMR spectrum confirmed that double esterification had taken place. Thus, the integration ratio of aromatic protons to methylene protons of succinic acid residues is 8: 8 (ppm range 5.9 - 7.1). The ratio of these methylene protons ^ (ppm 2,6) to the methyl protons of the methoxy group (ppm 3,8) is 8: 3 and is therefore in agreement.

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Also, chemical shifts in C investigations show that esterification was carried out on both alcohol OH groups, since chemical shifts change most strongly at and adjacent carbon atoms C ₁₂ - C ₁ , as well as at ^C 4 *

Elemental Analysis for Ο ^ Η ^ θΟ ^ (682,60)

C H 0 Calc .: 58.07 4,43 37,50 Found. : 58.05 4, 57 37, 31

Preparation of silibinin-C-2 ', 3-dihydrogensuccinate, disodium salts

K -In the ethanolic solution obtained according to Example 1, the amount of 6% ethanol sodium hydroxide, determined on the basis of the determination of the solids content in the above solution, was added dropwise during stirring and external cooling at -5 to 9 C, stirring the suspension for another hour at room temperature, extracted beige solid is sucked off, suspended twice after 5 to 10 min.

using Turrax in 150 ml of ethanol and suction again. To remove the remaining acetic acid ethyl ester, the product was then suspended for 14 hours at room temperature in 280 ml of ethanol, filtered off again, washed with 70 ml of ethanol and dried for 15 hours at 40 to. 45 ° C in a vacuum oven. The dried product is then ground, sieved to a grain size of less than 0.2 mm and dried for a further 48 hours at 40 to 45 ° in vacuo. This gave 52 g of the title compound (96% yield).

The title compound has no sharp melting point. It begins to sinter at about 80 ° C and melts at about 100 ° C with the formation of bubbles.

The UV spectrum in methanol shows λ = 288 nm, £, = 1.73 max

1θ \

The molar mass of the title compound is 726.56. The compound is a slight beige, microcrystalline powder with no special odor and salty taste. It is easily soluble in water, hardly soluble in ethanol and practically insoluble in acetone, ether and chloroform.

Claims (1)

PATENT APPLICATION A process for the preparation of silybinin derivatives of the general Formula I wherein it stands M for a hydrogen atom or an alkali metal atom, characterized in that 1 part by weight of silybinin of formula (A) is dissolved in 1 to 2 parts by weight of pyridine and, when stirred, is reacted at about 40 to 50 ° C with 1 to 3 parts by weight The dicarboxylic acid anhydride of the formula is then added ethanol until a homogeneous mixture is formed, then water is slowly added under intense stirring, with the present esters of the aromatic-bound OH groups hydrolyzed, faster when this hydrolysis is complete, diluted with ethyl acetate, washed with acidic water With a pH of 1.5 to 2.4, saturated with ethyl acetate, the ethyl acetate phase is evaporated, taken up in ethanol, and the alcoholic solution of alkali hydroxide is converted into the salt of the free carboxylic acid residue.