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 μg/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.