S_R-Podolactone D, a New Sulfoxide-Containing Norditerpene Dilactone from Podocarpus macrophyllus var. maki

S_R-Podolactone D (1), a new norditerpene dilactone having a methylsulfoxide moiety, was isolated from the leaves of Podocarpus macrophyllus D. Don var. maki Endl. along with known podolactone D (2, S_S-podolactone D). The structures and absolute configurations of compounds 1 and 2 were elucidated by spectral methods (HREIMS, IR, ¹H, ¹³C, and 2D NMR) and finally confirmed by single-crystal X-ray analyses. The cytotoxic effects of compounds 1 and 2 on P388 murine leukemia cells were also examined.