FI90081C - Process for the preparation of therapeutically active ginkgolide derivatives - Google Patents

Description

1 90081

The invention relates to a process for the preparation of various ginkgolide derivatives. The invention relates to a process for the preparation of various ginkgolide derivatives.

The invention relates to a process for the preparation of λ, B, C, J and M 1 -C 1 alkoxy and 10-C 1-4 alkoxy derivatives of ginkgolides. Preferred alkoxy groups are methoxy and ethoxy.

The invention provides a process for the preparation of 1-alkoxy and 10-alkoxy derivatives of ginkgolides A, B, C, J and M, which process comprises reacting ginkgolide A, B, C, J or M - dissolved in a non-polar solvent - with an excess of diazoalkane and Separation of a mixture of 1-alkoxygincgolide and 10-alkoxygincgolide.

20

In a preferred procedure, the selected ginkgol is dissolved in dioxane to a suitable concentration of 1 g / 100 ml, and the selected diazoalkane is dissolved in diethyl ether. The diazoalkane-containing solution is slowly added to the ginkgolide-containing solution using 10 equivalents of diazoalkane per equivalent of ginkgolide. The stirred solution is kept at ambient temperature for 3-8 hours to give a mixture of 1-alkoxygincgolide and 10-alkoxygincgolide. Separation of the two products obtained from the remaining unreacted ginkgolide can be conveniently carried out by removing the solvents by evaporating the residue and eluting the residue on a silica gel column using a 1: 1 by volume mixture of ethyl acetate and hexane as eluent. The resulting solution is evaporated to dryness, after which the residue is treated with chloroform, which dissolves the 10-alkoxy derivative. Said 10-alkoxy derivative is recovered from this chloroform solution, after which the remaining 2,900,81 solution is treated with diethyl ether to give the 1-alkoxy derivative.

The alkoxygincgolides 11a of the invention are important in the treatment of PAF-aster-induced diseases and thus the invention also provides a pharmaceutical composition comprising an A, B, C, J or M1 alkoxy derivative of ginkgolide or a 10-alkoxy derivative of two or more of said ginkgolides. -alkoxy and / or said 10-alkoxy derivatives in admixture as a mixture with a pharmaceutically acceptable diluent or carrier.

TOXICITY

15

The toxicity of the compounds of the invention was determined by oral administration to mice.

No deaths occurred at the maximum dose given to mice-20 la.

PHARMACOLOGY

Evidence of the pharmaceutical interest of the compounds of the invention was established by the following pharmaceutical experiments.

1) Inhibition of platelet aggregation in New Zealand rabbits ‘30 The experiments were performed on platelets derived from plasma obtained from New Zealand rabbits. Blood samples were taken from the ear artery and placed in citrate buffer (3.8%; pH 7.4), after which the blood was centrifuged for 15 minutes at 1200 rpm. The test sample was prepared in DMSO and then poured into platelet-containing plasma, after which a dose of 2.5 nMN PAF solution was added after 1 minute. Assay 3 90081 was performed on a Cronolog Coultronics-1 instrument that determines the% transmission corresponding to the maximum peak height before scattering.

a 5 Calculate the% inhibitory effect variation in relation to the% transmission (control: pure DMSO). This method is described in detail in: Laboratory Investigations 41: 3 (1979) 275, Jean-Pierre Cazenave, Dr.Med., Jacques Benveniste; Dr.Med., And J.Fraser Mustard, MD, 10 'Aggregation of Rabbits Platelets by Platelet-Actibating Factor is Indepedent of the Release Reaction and the Arachidonate Pathway and Inhibited by Membrane-Active Drugs' aggregation is not dependent on the associated release reaction or arachidone acid cycle and is inhibited by membrane activating drugs').

The results show that the compounds inhibit aggregation induced by 2.5 nM PAF solution. Using 20 experiments in 5 different rabbits, we were able to calculate the IC50 values of the different compounds by linear regression analysis.

We found the IC5Q values for platelets as follows: ·· 25

Ginkgo1idi type and substitution position_-OCH3_-QCoHg ___ B 1 - 6.6 10-7 1.1 10 "6 B 10 - 2.9 10" 7 7.2 10 "6 • 30 C 1 - 4.2 10-6 8 .5 10-6 c 10 - 3.0 10 ~ 6 9.3 10-6 A 1 - 4.6 10 ~ 6 8.7 10 "6 'A 10 - 1.3 10 ~ 5 6.2 10" 4 4 90081

Equivalent values 1Ginkgolidine11 e under the same conditions: 5 Ginkgolide A 8.32 x 10-6 Ginkgolide B 1.88 x 10-6 Ginkgolide C 1.53 x 10-5 Ginkgolide M 1.22 x 10-4 10 The results show that that the substitution has improved the pharmacological properties of the compounds.

2) Hypersensitivity bronchospasm in passively sensitized guinea pigs 15

Passive guest 1 driving sensitization

Male Hartely guinea pigs (400-500 g) were sensitized by intravenous (i.v.) injection of rabbit ovalbu-20 anti-mine immune serum (Cooper Biomedical, USA). To obtain a satisfactory hypersensitivity response, the following conditions were set after 24 hours: injection of diluted serum (half of the initial concentration: 0.05 ml / 100 g) into the penis.

25

Measurement of bronchospasm

The guinea pigs were anesthetized with urethane (2 g / kg, i.p.), after which their trachea was opened and breathing was maintained artificially by means of a breathing pump (UGO BASILE): stroke volume 1 ml / 100 g, 60 strokes / min.

An air breast was produced to prevent spontaneous respiration. The output resistance was kept constant at a water pressure of 10 cm according to the method of Konzett and Rössler and the excess air volume was measured by means of a bronchospasm transducer (UGO BASILE) connected to a UGO BASILE recorder 'Gemini'. A catheter for intravenous injection was placed in the jugular vein. Hypersensitivity shock was induced by intravenous injection of 0.75 mg / kg * passive foreign species sensitizer of ovalbumin. Compounds 5 were administered orally one hour before the antigenic sensitiser as a gummy aqueous suspension at a dose of 25 mg / kg.

Results 10 Ovalbumin-induced bronchospasm was expressed as a percentage of the maximum bronchospasm obtained by compressing the trachea completely. The results are shown in the following table.

15 Ginkgolide type and substitution position -OCH 2 -OC 2 H 5 B 1 - - 49.7 *** - 38.3 ** B 10 - - 54.9 *** - 36.2 ** C 1 - - 40.1 ** - 39.8 ** 20 C 10 - - 30.6 * - 23.1 *

A 1 - - 32.0 * - 15.1 NS

A 10 - - 25.2 * - 12.2 NS

NS: not significant 25 *: significant **: significantly significant ***: very significant

DOSAGE

30

For human treatment, the usual doses are 0.5 to 1 g per day in tablets or gelatin capsules for one month.

35 When using i.v. dosing is recommended three weekly injections of 0.5 to 0.2 g in isotonic solution for one month.

6 Ui 081

The following examples illustrate the invention:

Example 1

5-Methoxygin glycol-B and 10-methoxygin glycol-B

To a solution of ginkgolide-B in dioxane (10 g / liter) was slowly added 10 equivalents of a solution of diazomethane in diethyl ether. The mixture is maintained at ambient temperature for 4 hours, after which it was separated using the preferred separation procedure described above. 1-Methoxy-ginkgolide-B, the structure of which was confirmed by HPLC, was obtained in 66.1% yield and 10-methoxygincgol-di-B was obtained in 24% yield.

15

By the same method described above, but using ginkgolide A, C, J and M, the following yields were obtained.

20 1-methoxy 10-methoxy ginkgolide-A 56.3% 13.2% ginkgolide-C 49.1% 16.7% ginkgolide-J 46.2% 41.3% ginkgolide-H 37.5% 62.0 % 25

Example 2

1-ethoxygin glycol-B and 10-ethoxygin glycolide-B

Using the procedure described in Examples 1 but replacing diazomethane with diazoethane, 1-ethoxygincgolide-B was obtained (in 6 hours) in 63.2% yield and 10-ethoxygincogolide-B in 25.7% yield.

35 Proceeding as above using ginkgolides A, C, and M as starting materials, the following yields were obtained: 1 90081 1-ethoxy 10-ethoxy ginkgolide-A 72.8% 20.1% ginkgolide C 59.2% 30.4% 5 ginkgolide J 66.6% 15.3% ginkgolide-M 58.3% 30.5%

The melting points of the products are: 10 Melting points of derivatives (° C) Starting ginkgolide 1-methoxy 10-methoxy 1-ethoxy 10-ethoxy A 240 212 271 207 B 252 224 282 220 15 C 263 205 259 195 J 293 239 288 237 M 244 258 273 248

Claims (1)

A process for the preparation of therapeutically active 1-lower-5-alkoxy- or 10-lower-1-coxy-substituted ginkgolide derivatives, characterized in that a solution of the selected ginkgolide in dioxane is reacted with an excess of a solution of diazoalkane in diethyl ether at room temperature at 1-10 ° C. for an hour. 10 For the treatment of therapeutically active 1-carbon-alkoxy- or 10-carbon-alkoxy-substituted glycogen derivatives, 15 kännetecknat ar, h. 20