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

Abstract

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