New ent-trachylobane-3β-hydroperoxide (5) together with four known compounds, ricinine (1), trimethoxy ellagic acid (2), dimethoxy ellagic acid (3) and aleurotolic acid (4) were isolated from the methylene chloride fraction of the root bark of Chrozophora oblongifolia. The structures of these secondary metabolites were elucidated by using different spectroscopic techniques, 1H NMR, 13C NMR, HSQC, HMBC, 1H-1H COSY, NOESY, HR-ESI-MS, EI-MS and comparison with published data. Ent-trachylobane-3β-hydroperoxide showed moderate cytotoxic activity by MTT assay method against human breast cancer cells (MCF-7) and human hepatocyte-derived carcinoma cells (Huh-7) with IC50 values of 24.53 and 34.13 µM, in comparison with IC50 values of 23.47 µM and 15.82 µM for 5-fluorouracil respectively.
Keywords: Chrozophora oblongifolia; Trachylobane; cytotoxicity and MTT assay; diterpene.