Single solution phase conformation of new antiproliferative cembranes

Two new cembranes (2 and 3) have been isolated from thr extract of the Anta rctic sponge Lissodendoryx flabellata. Their structural elucidation has bee n performed by spectroscopic techniques, whereas the absolute configuration of the secondary carbinolic center was inferred by Mosher's method. The ab solute stereochemistry of the second asymmetric carbon, as well as the solu tion conformation of 2, has been determined by a computational approach bas ed on conformational search, restrained molecular dynamics and semi-empiric al calculations. The main product 2 showed cytotoxic and anti-proliferative activity against mammalian tumor cells. (C) 1999 Elsevier Science Ltd. All rights reserved.