Abstract

Four new labdane diterpenes, 1-4, with an unusual oxidation pattern have been isolated from the marine pulmonate Trimusculus peruvianus. The structure and stereochemistry of these compounds were determined by spectroscopic data and chemical transformations. The absolute stereochemistry of 4 was assigned by application of the modified Mosher method. These compounds exhibit in vitro moderate cytotoxic activity against human colon carcinoma cell lines. © 2003 Elsevier Science Ltd. All rights reserved.