Safety evaluation of polyphenols extracted from hop bracts

Hop bract polyphenols contain polyphenols as promising functional ingredients. To assess the safety of topical hop bract polyphenols, Hopsphenon, we examined acute, 14-day, 28-day and 90-day toxicity tests in rats, and mutagenicity tests using Ames test and micronucleus test in mice. The acute, 14-day, 28-day and 90-day toxicity tests revealed that Hopsphenon produced no symptoms of significant injury. The lethal dose of hop bract polyphenols is greater than 2000 mg/kg. The Ames test in the absence of S9 mix for TA98 and in the presence of S9 mix for TA1537 revealed that Hopsphenon had slight mutagenicity at a high dose of 5000 microg/plate; however, in the micronucleus test, Hopsphenon was negative. These tests demonstrated that hop bract polyphenols are safe and do not cause any detrimental effects in vivo under the conditions investigated in this study.