Evaluation of anticancer potential of sorghums with different genetic characteristics and levels of phenolic compounds

摘要

To evaluate the anticancer potential of sorghum phenolic compounds, differentexperiments including in vitro and in vivo tests were performed. A set of 25 sorghumsamples was evaluated for phenolic (total phenols, flavonoids, anthocyanins andtannins) content, hydrophilic and lipophilic antioxidant capacity using de OxygenRadical Absorbance Capacity assay (ORAC), and screened for citotoxic properties inmammary, colon and hepatic mammalian cancer cell lines in vitro. Results indicatedthat there was a wide variability in the phytochemical profile among the differentsorghums. Among the 25 samples, sumac sorghum bran had the highest amount ofphenolic compounds, flavonoids, tannins and the highest ORAC values. It exerted thehighest percent inhibition (near 100%) in mammary, colon and liver cancer cell lines.Sumac sorghum bran was selected for further investigation. Methanolic extracts fromsumac whole grain, bran and tannin removed bran were tested in vitro at differentconcentrations in hormone dependent MCF-7 mammary cancer cells and non hormonedependent Caco2 and HepG2 colon and liver cancer cells. Results indicated that themethanolic extract from sumac bran inhibited 100% of MCF-7 cancer cells at aconcentration of 0.5 mg/ml and that the citotoxic effect could be partially due to thetannin content of the extract. Concentrations of 0.5 and 1.5 mg/ml were selected for anin vivo preventive cancer study with 7,12-dymethylbenz(a)-anthracene (DMBA) inducedfemale rats. Bran at low and high concentrations and the correspondent amount ofmethanol extracts were included in the diet. It was observed that sumac methanolextract at low concentration promoted tumor appearance and development, whereassumac bran had a preventive effect, however, there were no significant differences inrats treated and un-treated with sumac. Differences between in vitro and in vivo results could be due to the degree of absorption of tannins during the in vivo experiment. Toobtain additional data about the effect of sumac extracts on cancer development, aquinone reductase enzyme bioassay was performed. Methanol and hexane extractsfrom sumac bran induced phase II enzymes in vitro. Phytochemicals of sumac bransorghum including phenolic compounds and lipid like compounds appeared to havepotential for cancer prevention.