Antiproliferative constituents of the roots of conyza canadensis

Abstract

Bioassay-guided fractionation of the n-hexane and CHCl3 phases of the methanol extract of the roots of Conyza canadensis (L.) Cronquist led to the isolation of two new dihydropyranones named conyzapyranone A (1) and B (2), and the known 4Z,8Z-matricaria-γ-lactone (3), 4E,8Z-matricaria-γ- lactone (4), 9,12,13-trihydroxy-10(E)-octadecenoic acid (5), epifriedelanol (6), friedeline (7), taraxerol (8), simiarenol (9), spinasterol (10), stigmasterol, β-sitosterol, and apigenin. The structures were determined by means of ESIMS and 1D and 2DNMR spectroscopy, including 1H-1H COSY, NOESY, HSQC, and HMBC experiments. The isolated compounds were evaluated for their antiproliferative activities and were demonstrated to exert considerable cell growth-inhibitory activity against human cervix adenocarcinoma (HeLa), skin carcinoma (A431), and breast adenocarcinoma (MCF-7) cells. Some of the active components, including 2, 4, and 10, proved to be substantially more potent against these cell lines than against noncancerous human foetal fibroblasts (MRC-5) and can therefore be considered selective antiproliferative natural products. © Georg Thieme Verlag KG Stuttgart - New York.