Antascomicins A, B, C, D and E. Novel FKBP12 binding compounds from a Micromonospora strain.

5 novel ascomycin-like compounds, antascomicins A, B, C, D and E were isolated from a strain of Micromonospora. The antascomicins bind strongly to the FK506-binding protein FKBP12 and antagonize the immunosuppressive activity of FK506 and rapamycin. The strain description, fermentation, structure elucidation and biological activity of these compounds are described.