GB486366A - Improvements in and relating to processes for the production of nucleosides - Google Patents

Abstract

Guanosine and adenosine are produced by causing emulsion to act on nucleic acids at a pH value of 4-5,5 and preferably at a slightly elevated temperature, e.g. 30-40 DEG C., crystallizing and separating the guanosine formed, precipitating the adenosine in the form of its picrate, and decomposing the picrate with a basic substance, preferably one forming a difficultly soluble picrate, e.g. potash or ammonia. The action of the emulsion should be continued preferably until the splitting off of phosphoric acid ceases, this occurring after about 8-14 or more days. The nucleic acids may be preliminarily degraded before treatment with emulsin by the action of alkali, e.g. a liquor having a 2-5 per cent alkali concentration. After heating on a water bath for a few hours, the hydrogen ion concentration is brought to the necessary value, e.g. by the addition of acetic acid, before the addition of emulsin. When an aqueous solution of picric acid is p used, it is generally necessary to evaporate the mixture in vacuum before the addition of the picric acid. The phosphoric acid can be removed by treatment with baryta water and excess barium removed by sulphuric acid. Evaporation can be entirely or in part dispensed with if solid picric acid is added to the solution freed from guanosine and albumen, but which may contain some sulphuric acid. In an example, a mixture of yeast nucleic acid and caustic solution is heated on a water bath for two hours. When the solution has cooled to 40 DEG C., acetic acid solution at 40 DEG C. and then an emulsion solution and a few drops of toluene are added. The solution is placed in an incubator at 37 DEG C. and is shaken daily. After 12-14 days, the solution is placed in an ice chest, and the guanosine formed is filtered and washed with water, alcohol and ether. The filtrate is boiled and cooled, and albumen then filtered off. Phosphoric acid is removed as above. The solution is evaporated somewhat, and heated to 50 DEG C., dry picric acid being then stirred in. After standing in an ice chest, adenosine picrate is filtered off, and washed with water, alcohol and ether. The picrate is crushed, treated in an Erlenmerger flask with water, and heated to 55 DEG C. Concentrated potash solution is then added, and after standing in ice water, potassium picrate is filtered off. The filtrate is seeded with adenosine, and after standing in an ice chest, the paste is filtered off, washed with water and then with acetone. The adenosine may be recrystallized from water. A 25 per cent ammonia solution may be used in place of the potash solution. Cytidine and uridine can be obtained from the filtrate obtained after precipitation of the adenosine with picric acid. A statement of the prior art refers to the action on yeast nucleic acid of juices expressed from spinach, or Cortinellus edodes or nucleotidases from liver, or intestinal mucus. The adenosine is isolated in the form of its picrate, which is decomposed by sulphuric acid. The yield is very small.