Neue Cyclopeptide aus Trichoderma polysporum (L INK EX P ERS .) R IFAI : Die Cyclosporine B, D und E

New Cyclopeptides from Trichoderma polysporum (LINK EX PERS.) RIFAI: Cyclosporins B, D and E Cyclosporins represent a new group of biologically active metabolites produced by Trichoderma polysporum (LINK EX PERS.) RIFAI and other fungi imperfecti. The structures of the main components, cyclosporins A (1) and C(3) have been determined as neutral cyclic oligopeptides composed of 11 amino acids, among them a new C9‐amino acid [2–4]. In addition, three minor metabolites, cyclosporins B, D and E, have now been isolated and characterized. Chemical investigation, spectroscopic evidence and X‐ray analysis led to the structural formulae of cyclosporins B (2) and D (4). Both compounds have the same sequence of amino acids as cyclosporin A (1), with the exception of L‐α‐aminobutyric acid, replaced in cyclosporin B (2) by L‐alanine and in cyclosporin D (4) by L‐valine, respectively. Cyclosporins undergo a characteristic intramolecular N,O‐acyl migration to furnish the corresponding basic isocompounds. The antifungal activities of cyclosporins are reported.