Cytotoxic activity of phenolic constituents from Echinochloa crus-galli against four human cancer cell lines

Abstract

Echinochloa crus-galli (L.) P. Beauv., Poaceae, grains are used as a feed for birds and millet for humans. The sulforhodamine B assay was used to assess its cytotoxicity against four human cancer cell lines. The ethanolic extract (70%) proved to be most active against HCT-116 and HELA cell lines (IC50=11.2±0.11 and 12.0±0.11μg/ml, respectively). On the other hand, the chloroform and ethyl acetate fractions exhibited their highest activities against HCT-116 cell lines. The chloroform and ethyl acetate fractions were subjected to several chromatographic separations to render pure phenolic compounds (1–8). Compounds 1–8 were identified as: 5,7-dihydroxy-3′,4′,5′-trimethoxy flavone, 5,7,4′-trihydroxy-3′,5′-dimethoxy flavone (tricin), quercetin, flavone, apigenin-8-C-sophoroside, 2-methoxy-4-hydroxy cinnamic acid, p-coumaric acid and quercetin-3-O-glucoside. All the isolated phenolic compounds exhibited various significant activities against the four human carcinoma where the methoxylated flavones (1 and 2) were the most active, in a way comparable to the anticancer drug Doxorubicin®. Thus, these methoxylated flavonoids may be considered as lead compounds for the treatment of cancer, which supports previous claims of E. crus-galli traditional use. This is the first report of the occurrence of these phenolic compounds in E. crus-galli.