Taxodin A, a Cytotoxic C₃₀ Terpenoid from Taxodium mucronatum with a Unique Skeleton

Taxodin A (1), a unique C-30 terpenoid featuring an unprecedented skeleton composed of an abietane-type diterpene and a menthane-type monoterpene, was obtained from the leaves and branches of Taxodium mucronatum. The structure and absolute configuration of compound 1 was unequivocally established by the combination of extensive spectroscopic analyses and X-ray single-crystal diffraction analysis. Compound 1 exhibited potent cytotoxic activities against A549, SMMC-7721, MDA-MB-231, and SW480 cell lines with IC50 values of 15.35 +/- 0.73, 8.49 +/- 0.35, 17.53 +/- 0.79, 18.93 +/- 0.60 mu M, respectively.