Derivatives of ML-236B carboxylic acid, its salts and esters and corresponding lactone have a hydroxy group at the 3"-position and optionally also at the 6'-position. These derivatives may be prepared by the enzymatic hydroxylation of a corresponding ML-236B compound employing an enzyme produced by a microorganism of the genus Streptomyces or Amycolata, especially Streptomyces sp. SANK 62285, Streptomyces sp. SANK 62385, Streptomyces sp. SANK 62485, Streptomyces sp. SANK 62585, Amycolata autotrophica SANK 62781, Amycolata autotrophica subsp. canberrica SANK 62882 or Amycolata autotrophica subsp. amethystina SANK 62981. These derivatives have the ability to inhibit cholesterol biosynthesis.