Extraction and antioxidative activities of polyphenols from sesame leaves

The extraction process and antioxidant activities of polyphenols from sesame leaves were studied in vitro. The microwave-assisted extraction technology of polyphenols was investigated by L16(44) orthogonal experiment methodology on the basis of single factor test. Meanwhile,the antioxidant activities of crude polyphenols were also evaluated by various methods,such as ABTS radical scavenging activity,inhibition to lipid peroxidation,and reduction power. The results showed that the optimal extraction conditions were as follows: 70%(v/v) ethanol as the solvent,material-solvent ratio1:50(g/mL),microwave power 420 W,microwave time 120 seconds,and the extraction times 2. Under the optimal conditions,the extraction ratio of polyphenols can reach to(45.89±1.66) mg/g. And then,the raw polyphenols were found to have strong ABTS radical scavenging activities with 50% inhibition concentrations(IC50) of 3.77 mg/L. It also exhibited effectively lipid peroxidation inhibitory activities with IC50 of 30.50 mg/L. It exhibited excellent antioxidant activity,as strong as that of the positive control(Vc). The reduction power of raw polyphenols on Fe3+ was poorer than that of Vc. These suggest that polyphenols from sesame leaves have obvious antioxidant ability in vitro.