Study on the differences in antioxidant and lipid lowering activities of different barley polyphenols

Two different barley polyphenols were prepared by fermentation (Lactiplantibacillus plantarum dy-1) and enzymatic hydrolysis (sulfatase), respectively. The phenolic compounds composition of fermented barley polyphenols (FBP) and enzymatic hydrolysis barley polyphenols (EBP) were analyzed. The antioxidant abilities and lipid-lowering effects of FBP and EBP were further investigated. The results indicated that total phenol contents of EBP and FBP were 78.35 μg GAE/mL and 146.56 μg GAE/mL, respectively. The absolute contents of vanillin, benzoic acid, 2, 4-dihydroxybenzoic acid, epicatechin and salicylic acid were significantly different between EBP and FBP. Under the condition of the same total phenol content, vanillin, chlorogenic acid, and gallic acid are characteristic components of the EBP while benzoic acid, 3, 4-dimethoxybenzoic acid and epicatechin are characteristic components of FBP. Compared with EBP, the DPPH and ABTS+ free radical scavenging rates of FBP were increased by 36.8% and 13.3%. At 20 μg GAE/mL total phenol content, both FBP and EBP effectively reduced the accumulation of lipid droplets, and reduced the triglyceride content by 23.3% and 27.9%, respectively, in Caenorhabditis elegans. In terms of lipid-lowering mechanism, both FBP and EBP could promote the movement of C. elegans to accelerate its lipid consumption and inhibit the abnormal activation of the SBP-1 signaling pathway. The effect of EBP on the insulin/insulin-like growth factor signaling pathway was more significant than that of FBP (P< 0.05). In conclusion, when total phenol content is the same, the composition differences of barley polyphenols could significantly affect their antioxidant ability and lipid-lowering effect.