Polyphenol contents of five of medicinal plants from Cameroon and effects of their extracts on antioxidant capacities of human breast cancer cells

The aim of the study was to investigate the antiproliferative properties of extracts of five plants on breast cancer cells (MDA-MB-231) and their effects on antioxidant activities. The total phenol contents of the extracts were determined to establish a correlation to their antiproliferative effects which were evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide viability assay. Enzymes involved in oxidative stress were also determined. Total polyphenol contents of the five extracts varied from 170 to 440 mg L^?1 of gallic acid per mg of extract with the highest value for the extract of Sida cordifolia. Cell growth inhibition was observed within 24 h, with inhibitory concentration values ranging from 7.3 to 25 mg L^?1 depending on plant extract. At concentrations between 100 and 200 mg L^?1, all the extracts exhibited significant reduction of cell proliferation in time-dependent and linear manner. The activities of superoxide dismutase and catalase of cells treated for 24 h with the extract of S. cordifolia were 3.5 U per mg protein and 8 mole H₂O₂ consumed per min per mg protein higher than those of cells treated with an extract of Viscum album.