Die Struktur von Cyclosporin C

The Structure of Cyclosporin C The structure of cyclosporin C (2), a minor antifungal metabolite from Trichoderma polysporum (Link ex Pers.) RIFAI has been elucidated. Hydrolytic cleavage and spectroscopic evidence show that cyclosporin C is a neutral oligopeptide of 11 amino acids linked together in a 33‐membered ring. Cyclosporin C (2) differs from the main metabolite cyclosporin A (1) [2] [4] only by containing L‐threonine in the place of L‐α‐aminobutyric acid as has been shown by the conversion of 2 into 1. 13C‐NMR. spectra and study of molecular models suggest that cyclosporin C (2) has the same molecular conformation as 1, which is best described as a twisted β‐pleated sheet held together in a conformationally stable form by intramolecular hydrogen bonding.