DEEPOXIDATION OF 16-MEMBERED EPOXYENONE MACROLIDE ANTIBIOTICS

I. MICROBIAL DEEPOXIDATION AND SUBSEQUENT ISOMERIZATION OF DELTAMYCINS A₁, A₂, A₃, A₄ (CARBOMYCIN A) AND X

Abstract

Carbomycin A (deltamycin A₄) was deepoxidized to carbomycin A P1 by Streptomyces halstedii subsp. deltae (a deltamycins producer), favorably under anaerobic conditions. Carbomycin A P1 was spontaneously converted to geometric isomers designated carbomycins A P2 and A P3. This type of deepoxidation and subsequent isomerization was not limited to carbomycin A, but generally occurrable in other 16-membered epoxyenone macrolide compounds. Many bacteria and actinomycetes were also found to have an ability to deepoxidize deltamycins reductively. The chemical structures of carbomycins A P1, A P2 and A P3 were elucidated as shown in Fig. 3.