Cyclamenols E and F, two diastereoisomeric bicyclic macrolactams with a cyclopentane moiety from an Antarctic Streptomyces species

Abstract

Cyclamenols E (1) and F (2), two bicyclic macrolactams possessing a cyclopentane moiety, were isolated from the Antarctic Streptomyces sp. OUCMDZ-4348. Their structures, including absolute configurations, were determined by spectroscopic analysis, chemical derivatization, and ECD calculation. Treatment of compound 1 with 2,2-dimethoxypropane and pyridinium p-toluenesulfonate in acetone/DMF led to the formation of acetonide 1a with an unexpected skeleton. Compound 1 showed moderate inhibitory activity against the gastric carcinoma cell line N87 with an IC₅₀ value of 9.8 μM, but no cytotoxicity was observed on the other 25 cancer cell lines tested.