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 ± 0.11 µg/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.

Pyrrolizidine alkaloids in medicinal tea of Ageratum conyzoides

It is now widely-recognized that the view that herbal remedies have no adverse effects and/or toxicity is incorrect; some traditionally-used plants can present toxicity. The well-established popular use of Ageratum conyzoides has led to its inclusion in a category of medicinal crude drugs created by the Brazilian Health Surveillance Agency. Ageratum belongs to the Eupatorieae tribe, Asteraceae, and is described as containing toxic pyrrolizidine alkaloids. Aqueous extracts of Ageratum conyzoides L. harvested in Brazil (commercial, flowering and non-flowering samples) were prepared according to the prescribed method and analyzed by HPLC-HRMS. The pyrrolizidine alkaloids lycopsamine, dihydrolycopsamine, and acetyl-lycopsamine and their N-oxides, were detected in the analyzed extracts, lycopsamine and its N-oxide being known hepatotoxins and tumorigens. Together with the pyrrolizidine alkaloids identified by HPLC-HRMS, thirteen phenolic compounds were identified, notably, methoxylated flavonoids and chromenes. Toxicological studies on A. conyzoides are necessary, as is monitoring of its clinical use. To date, there are no established safety guidelines on pyrrolizidine alkaloids-containing plants, and their use in Brazil.