Structural Determination of Stevastelins, Novel Depsipeptides from Penidllium sp.

Abstract

Structures of novel immunosuppressants, stevastelin A, B and B3¹⁾ were determined by their spectroscopic and chemical studies. Three stevastelins were shown to be cyclic depsipeptides composed of a fatty acid and three amino acid moieties. The sequence of these moieties was determined to be as 3, 5-dihydroxy-2, 4-dimethylstearylvalylthreonyl (or O-sulfonylthreonyl in stevastelin A)-O-acetylserine. Cyclic structures were shown to be formed by ester linkages between the carboxylic group of the O-acetylserine moiety and the 5-hydroxy group of the fatty acid moiety in stevastelin A and B, and the 3-hydroxy group of the fatty acid moiety in stevastelin B3.