Three new phenanthrenone constituents from Trigonostemon lii

Three new phenanthrenone constituents, trigoxyphins U-W (1, 7 and 9), together with eight known ones, trigoxyphin M (2), 6,9-O-dimethyltrigonostemone (3), trigonstemone (4), thrigonosomone B (5), trigonochinene E (6), actephiiol A (8), epiactephilol A (10) and neoboutomannin (11), were obtained from the methanol extract of the leaves and stems of Trigonostemonlii. The structures of the new metabolites were elucidated by analysing the spectroscopic data (1D NMR, 2D NMR, HR-ESI-MS and IR). Compounds 1-6 were evaluated for their cytotoxic activities on five human tumour cell lines by using the MTT method, and compound 1 exhibited inhibitory activity against HL-60, SMMC-7721, A-549, MCF-7 and SW480 with IC50 values ranging from 3.77 to 14.51 μM.