Chemical constituents from the Knema globularia fruits and their in vitro cytotoxicity.

Two new compounds, designated as knecorticosanones A-B (1-2), along with three known compounds (3-5) were isolated from the fruits of Knema globularia. Their structures were elucidated by extensive spectroscopy analysis, including 1D- and 2D-NMR, UV, IR, and HRESIMS and by comparison with the reported data in the literature. Compounds 1-5 were evaluated for their cytotoxicity. Knecorticosanone B (2) and malabaricone D (5) exhibited moderate cytotoxic effect against Hep-G2, MCF-7 and SK-LU-1 cell lines with IC50 values ranging from 8.76 ± 1.02 to 18.74 ± 1.75 µM while knecorticosanone A (1), virolane (3) and 7-hydroxy-3',4'-methylenedioxyflavan (4) exhibited weak inhibitory effect against these cell lines with IC50 values ranging from 25.85 ± 2.75 to 66.75 ± 2.08 µM.