Cespitulactams A, B, and C, three new nitrogen-containing diterpenes from Cespitularia taeniata May

Three new nitrogen-containing diterpenoids, designated cespitulactams A (1), B (2), and C (3), were isolated from Cespitularia taeniata May. Compounds 1–3 are novel structures having a phenylethyl amino side at C-10 and with an amide function at C-20. Their structures were determined on the basis of extensive spectroscopic analysis and chemical correlation. The cytotoxicity of 1 and its monoacetate (6) were also evaluated against human cancer cell lines.