Scalalactams A⁻D, Scalarane Sesterterpenes with a γ-Lactam Moiety from a Korean Spongia Sp. Marine Sponge.

Intensive study on the chemical components of a Korean marine sponge, Spongia sp., has led to the isolation of four new scalarane sesterterpenes, scalalactams A⁻D (1⁻4). Their chemical structures were elucidated from the analysis of spectroscopic data including 1D-and 2D-NMR as well as MS data. Scalalactams A⁻D (1⁻4) possess a scalarane carbon skeleton with a rare structural feature of a γ-lactam moiety within the molecules. Scalalactams A and B (1 and 2) have an extended isopropanyl chain at the lactam ring, and scalalactams C and D (3 and 4) possess a phenethyl group at the lactam ring moiety. Scalalactams A⁻D (1⁻4) did not show FXR antagonistic activity nor cytotoxicity up to 100 µM.