Scalarane and homoscalarane compounds from the nudibranchs Glossodoris sedna and Glossodoris dalli: Chemical and biological properties

A series of homoscalarane and scalarane compounds (2-7) have been isolated from two distinct species of Pacific Glossodoris nudibranchs. The structure and elucidation of the relative stereochemistry of the new metabolites 2 and 3 were obtained by spectroscopic methods. Compound 2 was ichthyotoxic at 0.1 ppm against Gambusia affinis and showed moderate activity (IC50 18 mu M) to inhibit mammalian phospholipase A2.