GB2144409A - Preparation of 5'-deoxy-5'-methylthioadenosine - Google Patents

Abstract

A method of preparing 5'-deoxy-5'-methylthiodenosine comprises hydrolysing a concentrated aqueous solution of S-adenosyl-methionine by heating under reflux, neutralising the reaction mixture and cooling it to separate the 5'-deoxy-5'-methylthioadenosine formed.

Description

1 GB 2 144 409 A 1

SPECIFICATION

Preparation of 5'-deoxy-S'-methyithioadenosine This invention is concerned with improvements in and relating to 5'-deoxy- 5'-methyithioadenosine. In our copending application No. 8112428 we describe and claim therapeutic compositions of antiffif lammatory, analgesic and antipyretic activity in dosage unit form and containing, from 25 to 100.2 mg of an active principle of the general formula:

HH-Rl c W H LH2--K 0 OR2 OR2 (1) in which: R is a linear or branched alkyl radical containing 1-18 C atoms or a phenylalkylene radical in which the alkylene chain contains 1-6 C atoms; R, is H, an aliphatic acyl radical containing 1-6 C atoms or an aromatic acyl radical; R2 is H; and n is 0 or 1. Of all the products prepared, the one which has proved particularly interesting is 5'-deoxy- 5'methylthioadenosine (MTA) of the formula:

NH2 0 ON ON EN2-S-EN3 (H) A method has been found for preparing this product which is particularly simple and economical from an industrial viewpoint. The new process consists essentially of carrying out hydrolysis of Sadenosyimethionine (SAME) under strictly controlled critical conditions, which lead to practically total hydrolysis and complete crystallisation of the IVITA 1H2 NH2 j 1 H20 CH -S-CH -CH - CH - COON H N 2 2 2 Y0 CH3 ON ON N 1. ' J > CH -5-CH N H 0 2 3 ON ON NH2 1 HO-Ln-Lt'2LM-LOOH+H+ GB 2 144 409 A The controlled hydrolysis process can be applied to SAME prepared in any manner.

However, the method of preparation of the SAME solution is also an influencing factor in carrying out the new process in an economically convenient manner.

The following operational stages provide the most economical embodiment of the process:

(a) Normal bread yeast is enriched in SAME by treatment with methionine in accordance with the Schienk method (Schlenk F (1975) Enzymologie 29, 283).

(b) The yeast cells suspended in water are lysed by treatment with ethyl or methyl acetate at ambient temperature (DT-OS P23 36401.4).

By adjusting the pH to between 4 and 6 and filtering, an aqueous solution is obtained containing practically ail the SAME present in the initial yeast.

(c) The solution is concentrated under vacuum at 35-40'C to about 1/10 of its initial volume.

(d) The concentrate is boiled uner reflux for about 30 minutes and the pH is adjusted to 7 with soda.

(e) The solution is left to stand at 0 - WC, and the precipitated IVITA is collected practically completely and in good purity.

The steps of c, d and e, which as stated are critically necessary for obtaining complete selective hydrolysis 15 of SAME to MTA without formation of by-products, are new.

The following example illustrates the present invention.

Example

Preparation of 5'-deoxy-5'-methylthioadenosine(MTA) 11 litres of ethyl acetate and 11 litres of water at ambient temperature are added to 90 kg of bread yeast which has been enriched in SAME by adding methionine until the SAME content is 6.88 glkg. After energetic stirring for 30 minutes, the pH is adjusted to 4.5 with dilute H2S04, the mixture is filtered and the residue is washed with waterto give 140 litres of solution with a SAME content of 4. 40 g/1, equal to 99.5% of the SAME present in the initial material.

The lysate thus obtained is concentrated under vacuum (30 mm Hq; 35-40'C) to a volume of about 14 litres.

The concentrated solution is boiled under reflux at normal pressure for 30 minutes. It is cooled to 20'C, the pH adjusted to 7 with 40% by weight soda, andleft overnight in a refrigeration cell (+3'C). A white precipitate is formed which is filtered, dissolved in 10 litres of boiling distilled water and crystallised by cooling this solution. 410 g of crystalline MTA of high purity are obtained, equal to a yield of 90% with respect to the 30 SAME subjected to hydrolysis.

The characteristics of the product obtained coincide with those of pure MTA obtained by other means.

Claims (3)

1. A process for preparing 5'-deoxy-5'-methyi-thioadenosine, wherein Sadenosyl-methionine in concentrated aqueous solution, is hydrolysed by heating under reflux, and the 5'-deoxy-5'-methyithioadenosine formed is precipitated from the aqueous solution by cooling after neutralising the reaction mixture.

2. A process as claimed in claim 1 wherein the aqueous solution of Sadenosyl-methionine is 40 concentrated by heating under vacuum to 35 40'C.

3. A process as claimed in claim 2 or claim 3, wherein the 5'-deoxy-5'methyithioadenosine formed is precipitated by cooling to O-WC.

Printed in the UK for HMSO, D8818935, 1185, 7102. Published by The Patent Office, 25 Southampton Buildings, London, WC2A lAY, from which copies may be obtained.

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