Abstract:

A high-purity hop polyphenol extract (HPE) (containing 88.7% of total phenolics) was prepared from spent hops in
the present study. The phenolic compositions of HPE were determined and its in vivo and in vitro antioxidant activities were
evaluated by comparison with those of green tea polyphenols. The results showed that the phenolic compositions of HPE
included more than 55% proanthocyanidins and more than 28% flavonoid glycosides. in vitro, HPE effectively scavenged
reactive oxygen species and inhibited Cu2+ vitamin C-induced oxidative DNA damage. in vivo, orally administered HPE at
polyphenol doses of 200 to 800 mg/kg body weight significantly prevented a bromobenzene-induced decrease in hepatic
superoxide dismutase and glutathione peroxidase activity, and decreased the levels of hepatic thiobarbituric acid reactive
substance in bromobenzene-treated mice. HPE at the oral doses of 200 to 800 mg/kg body weight significantly reduced the
frequency of bone marrow micronuclei induced by cyclophosphamide. These results suggest that dietary hop polyphenols
could provide protection from oxidative mutagenic in vivo and in vitro damage. The in vivo and in vitro antioxidant activities
of hop polyphenols were higher than those of green tea polyphenols at the same concentration.

Key words: hop polyphenol, proanthocyanidins, flavonoid glycosides, antioxidant activity, mice, DNA, tea polyphenols