Homalolides C-D, two new sesquiterpenoids from the rhizomes of Homalomena pendula

Two new sesquiterpenoids, homalolides C - D (1-2), were co-isolated from the rhizomes of Homalomena pendula (Blume) Bakh.f collected in Vietnam with five known ones, aromadendrane-4 alpha,10 alpha-diol (3), bullatantriol (4), 1 beta,4 beta,6 alpha-trihydroxy-eudesmane (5), 1 beta,4 beta,6 beta-trihydroxyeudesmane (6), and 1 beta,4 beta,7 alpha-trihydroxy-eudesmane (7). The structures and relative configuration of new compounds were elucidated by 1 D-/2D-NMR, IR, UV and HRESIMS analyses, and by comparisons to the reported data in the literature. Homalolide C presented an unprecedented skeleton with the 4/8 bicyclic system. All isolates did not exhibit appreciable inhibitory effects on LPS-induced NO production in the RAW 264.7 macrophage cell line and on the growth of human lung cancer cell line (SK-LU-1).