Abstract: A method of isolating or purifying pravastatin or its pharmaceutically acceptable salt characterized by involving, in the process of isolating or purifying pravastatin or its pharmacologically acceptable salt, the step of extracting pravastatin using an organic solvent represented by the formula CH3CO2R wherein R represents an alkyl group having 3 or more carbon atoms or the step of decomposing impurities using an inorganic acid or an inorganic base; and compositions containing pravastatin sodium thus obtained.

Abstract: The present invention provides methods for purification of pravastatin or a pharmacologically acceptable salt thereof using a salting-out technique. Inorganic salts are added to an aqueous solution of pravastatin of a pharmacologically acceptable salt thereof which was obtained from culturing of microorganisms, to selectively precipitate the pravastatin or pharmacologically acceptable salt.

Abstract: 5-Amino-1-(hydroxymethyl)cyclopentane-1,2,3,4-tetraol and 2-amino-4-(hydroxymethyl)-3a,5,6,6a-tetrahydro-4H-cyclopent[d]oxazole-4,5, 6-triol, which have the ability to inhibit the activity of sugar hydrolases, especially .beta.-glucosidase and sucrase and can thus be used for the treatment and prophylaxis of tumorous conditions, AIDS, diabetes and obesity, can be prepared by hydrolysis of trehazolin. 2-Amino-4-(hydroxymethyl)-3a,5,6,6a-tetrahydro-4H-cyclopent[d]oxazole-4,5, 6-triol can also be prepared by fermentation using newly isolated strains Micromonospora sp. SANK 62390, FERM BP-3521 and Amycolatopsis sp. SANK 60791, FERM BP-3513.