New sesquiterpenes from the rhizomes of homalomena occulta.

Six new sesquiterpenes (1–6), along with eight known ones (7–14) were isolated from the rhizomes of Homalomena occulta. Structure elucidation of the new compounds was achieved through 1D NMR, 2D NMR spectroscopic techniques and HRESIMS, while the absolute configurations of compounds 1, 2 and 5 were confirmed by X-ray crystallographic analysis. All of the isolates were evaluated for their activity against LPS-induced production of nitrogen oxide (NO) in macrophage cells, and compounds 1 and 5 showed inhibitory effect on NO production with the IC50 values of 21.2 and 15.4μM, respectively.