New sesquiterpene formamides from the marine sponge Axinyssa sp.

Abstract

Chemical investigation of an extract of the marine sponge Axinyssa sp., collected from the South China Sea, led to the isolation and identification of two new sesquiterpene formamides, (4R*,5R*,10R*)-4- formamidoeudesm-7-ene (1) and (4R*,5R*,7S*,10R*)-4- formamidoeudesman-11-ol (2), together with the known 4α-formamidogorgon- 11-ene (3). Their structures were elucidated by spectroscopic methods, including 1D- and 2D-NMR spectroscopy, high-resolution ESI-TOF mass spectrometry, as well as X-ray single-crystal diffraction experiments. Possible biosynthetic pathways for 1-3 were also proposed. The human nasopharyngeal cancer cell line CNE-2, human cervical cancer cell line HeLa, and human normal liver cell line L02 were used to examine the cytotoxic activities of 1-3 in vitro. As the results, 1 showed significant cytotoxic activity against CNE-2, HeLa, and L02 cell lines with the IC50 values of 13.8, 7.5, and 38.0 μg/ml, resp. © 2008 Verlag Helvetica Chimica Acta AG.