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.) R IFAI 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 . 13 C‐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.