Chemical constituents from the soft coral cladiella tuberosa tixier-durivault

Abstract

The bioassay-directed fractionation, using cytotoxic and brine shrimp lethality activities, of the dichloromethane extract from the soft coral Cladiella tuberose led to the isolation of four eunicellin diterpenoids : 3-deacetylpalmonin A which is a new eunicellin derivative, deacetylcladiellin which is reported for the first time as naturally occurring, sclerophytin A which has never been found in soft corals of the genus Cladiella, and (1R, 2R, 3R, 6S, 9S, 10R, 14R)-cladiell-7(19),11(20)-dien-3,6-diol. The structures and relative stereochemistry of the compounds were elucidated through extensive analyses of their ir, ms, ¹H and ¹³C nmr spectral data, expecially 1D- and 2D-nmr, as well as comparison with known related compounds. Deacetylcladiellin showed cytotoxic activity against P-388 with IC₅₀ value of 2 µg/ml, whereas for HT-29, A-549, and MEL-28 the IC₅₀ was 5 µg/ml and also showed brine shrimp lethality activity with LD₅₀ of 0.6 µg/ml.