Content of Total Phenols,Flavonoids and Its Antioxidant Activities of Various Solvent Polyphenol Extracts from Yellow Onion Peel

Yellow onion peel(YOP)were extracted using three solvent systems:70% acetone,70% ethanol and 70% methanol. The extracts were tested for their total phenolic content,total flavonoid content and antioxidant activities(ferric ion reducing antioxidant power(FRAP),DPPH(1,1-diphenyl-2-picrylhydrazyl)radical scavenging,ABTS(1,1-diphenyl-2-picrylhydrazyl)radical scavenging). The results showed that the extract with methanol as the extraction agent had the highest yield(12.35%),and the extract had the highest total phenol content(83.17 mg/g)and total flavonoids content(34.31 mg/g). Meanwhile,IC₅₀ of methanol extract on DPPH free radical and ABTS free radical was 0.059 mg/mL and 0.031 mg/mL,respectively,lower than ascorbic acid but higher than ethanol extract and acetone extract.