New cyclopeptides from Trichoderma polysporum (Link ex Pers.) Rifai: cyclosporins B, D and E (author's transl)

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.