Abstract: Three varieties of SAST hops were extracted with solvents of different polarities including petroleum ether, chloroform, ethyl acetate, n-butanol and water. The contents of α-acids, β-acids, total flavonoids and total polyphenols in these extracts were measured and compared. Their antioxidant activities were evaluated by hydroxyl radical scavenging, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and β-carotene-linoleic acid model system assays. The correlation was analyzed between the antioxidant activity and the contents of bioactive ingredients. The results showed that all parts of hops displayed antioxidant activity. α-Acids and β-acids were more abundant in the petroleum ether extracts, which ranged between 444.29-583.81 and 131.83-293.19 mg/g, respectively; however, lower values were detected in the chloroform extracts, and undetectable levels were found in other extracts. The correlation analysis suggested that α-acids and β-acids were the main antioxidant compounds in the petroleum ether and chloroform extracts. The medium and highly polar solvent extracts were rich in total flavonoids and total polyphenols, which were the main antioxidant compounds. For all three varieties, the highest contents of total flavonoids (20.43-24.13 mg/g) and total polyphenols (34.97-40.24 mg/g) were in the ethyl acetate extracts followed by the n-butanol extracts (9.45-11.68 and 12.12-19.14 mg/g).

Key words: hops, α-acids, β-acids, total flavonoids, total polyphenols, antioxidant activity, correlation