Terpenoids from the whole plants of Chloranthus holostegius

The phytochemical reinvestigation on the whole plants of Chloranthus holostegius led to the isolation of five undescribed sesquiterpenes (named chloranholosins U-Y, 1-5), including two lindenane-type sesquiterpenes, two acorane-type sesquiterpenes, and one elemane-type sesquiterpene, together with 30 known compounds. Their structures and absolute configurations were elucidated by a comprehensive method including the spectroscopic data, and electronic circular dichroism (ECD) calculations. Chloranholosin U (1) was elucidated as a rare lindenane-dinormonotepenoid hybrid with an oxa-difuranofurone moiety. Furthermore, all new isolates and 18 known compounds were evaluated for their inhibitory activity against LPS-induced nitric oxide (NO) production in RAW 264.7 macrophage cells, while their cytotoxic activities were also assessed against five human tumor cell lines. Though these compounds did not show inhibitory activity for NO production, compounds 16, 34, and 35 displayed moderate cytotoxicity. Compound 16 showed cytotoxicity against HL-60, HepG2, MDA-MB-231, and SW480 (IC₅₀ 10.98-36.48 μM), compounds 34 and 35 were active on HL-60 (IC₅₀ 18.98 and 14.89 μM), and 34 also inhibited A549 (IC₅₀ 24.32 μM).