ABSTRACT
Objective: To investigate the chemical constituents of the barks and stems of Melaleuca alternifolia and its antitumor activities. Methods: The chemical constituents were separated and purified consecutively by silica gel, Sephadex LH-20 column chromatography, recrystallization as well as preparative HPLC. Their structures were determined by physicochemical properties and spectral analyses. Furthermore, the cytotoxicity of some compounds against PC-9 (human non-small cell lung cancer cell line), HT29 (human colon cancer cell line) and MCF-7 (human breast cancer cell line) were tested by CCK8 method. Results: Eleven compounds were isolated and identified as ursolic acid 3-O-β-cis-caffeate (1), ursolic acid 3-O-β-trans-caffeate (2), tricontyl ferulates (3), 3-O-acetyl-11(12)-en-urs-28,13β-olide (4), 3-O-acetyl-ursolic acid (5), tricontyl caffeate (6), ursolic acid (7), n-nonacosanol (8), urs-12(13)-en-3-one-28-oic acid (9), 3β-O-acetyl-11α,12α-epoxy-oleanane-28,13β-olide (10), and betulin (11). Conclusion: Compound 1 and 2 are cis-trans isomers. Compound 1 is isolated from natural product for the first time, all the compounds are isolated from this plant for the first time except for compound 11. Compound 1 exhibited moderate inhibited effect on the proliferation of three human cancer cell lines.