Studies on juvenimicin, a new antibiotic. II. Isolation, chemical characterization and structures

A series of new macrolide antibiotics was isolated from the culture filtrate of Micromonospora chalcea var, izumensis. The fat-soluble basic complex consisted of eight components which were named juvenimicin A1 approximately A4 and B1 approximately B4. Juvenimicin A3 was found to be identical with rosamicin and the structures of four of the other components (JVM A2, A4, B1 and B3) have been elucidated. Juvenimicin A2 has a methyl group at position 6 instead of the formylmethyl group of juvenimicin A3. Juvenimicin A4, B1 and B3 possess a hydroxyethyl group at position 6. Juvenimicin A4 and B1 differ from each other in the nature of the chromophore. Juvenimicin B3 differs from juvenimicin B1 in that a hydroxymethyl group is present at position 14 in the former.