Effect of acidic condition on phenolic composition and antioxidant potential of aqueous extracts from sorghum (Sorghum Bicolor) bran

摘要

The effect of extraction under acidic condition (pH 2) on phenolic compounds andantioxidant potential of aqueous extracts fromcondensed tannin sorghumbran wasinvestigated. The protective effect of extracts prepared with water (WE) and acidifiedwater (pH 2) (AWE) against free radical-induced red blood cell hemolysis andlow-density lipoprotein (LDL) oxidation was determined. The % yield (grams offreeze-dried aqueous extract/100 g of dry sample weight), total phenolic, flavonoidcontent and 2,2-diphenyl-1-picrylhydrazyl radical-scavenging activity were significantlyhigher in AWE than WE. AWE had 19% higher overall content of identifiedphenolic acids and flavonoids thanWE.AWE showed a significantly higher degree ofprotection against erythrocytemembrane oxidation than WE. Both extracts showedprotective effect against LDL oxidation. However, there were no significant differencesin tannin content and oxygen radical absorbance capacity values between theextracts. Extracting sorghum bran under acidic conditions may release bound phenoliccompounds thereby improving the health-promoting benefits of extracts fromsorghumbran.