Single solution phase conformation of new antiproliferative cembranes

Two new cembranes (2 and 3) have been isolated from thr extract of the Antarctic sponge Lissodendoryx flabellata. Their structural elucidation has been performed by spectroscopic techniques, whereas the absolute configuration of the secondary carbinolic center was inferred by Mosher's method. The absolute stereochemistry of the second asymmetric carbon, as well as the solution conformation of 2, has been determined by a computational approach based on conformational search, restrained molecular dynamics and semi-empirical calculations. The main product 2 showed cytotoxic and anti-proliferative activity against mammalian tumor cells.