Genotoxicity assessment of Hwanglyeonhaedok-tang: an herbal formula evaluated using the in vivo alkaline comet assay and Pig-a gene mutation assay in rats.

BACKGROUND: Hwanglyeonhaedok-tang (HHT), also known as Huang-lian-jie-du-tang or Oren-gedoku-to, is a popular herbal formula in traditional Asian medicine. Despite the clinical effectiveness of herbal formulas, concerns regarding the quality, safety, and efficacy persist. HHT exhibited genotoxicity in bacterial reverse mutation (Ames test) and in vitro chromosomal aberration (CA) test, warranting further investigation. This study aimed to assess the genotoxic potential of HHT using in vivo assays, including the alkaline comet and phosphatidylinositol glycan class A (Pig-a) gene mutation assays, since HHT previously showed positive results only in in vitro tests. METHODS: The in vivo comet assay was conducted on rat liver under Good Laboratory Practice standards to assess DNA migration, focusing on % tail DNA and hedgehog frequency (cells with small or absent heads and diffuse tails). The Pig-a gene mutation assay used peripheral blood to evaluate mutant red blood cells (RBCs) and reticulocytes (RETs), with cytotoxicity assessed by %RET. Doses of 0, 500, 1,000, and 2,000 mg/kg were tested, applying standard statistical methods. RESULTS: The comet assay showed no marked increases in % tail DNA or hedgehog frequency at the doses tested. In Sprague–Dawley male rats, no clinical signs, behavioral abnormalities, or weight changes were observed. Similarly, the Pig-a assay revealed no significant differences in mutant RBCs or RETs, and %RET cytotoxicity was comparable to controls. Positive controls validated assay sensitivity. Overall, HHT did not induce genotoxicity and cytotoxicity under tested conditions, supporting its safety at the evaluated dose levels. CONCLUSIONS: The in vivo comet assay results suggest that the positive outcome observed in the in vitro CA test is likely a false positive. However, although negative result was obtained from short-term Pig-a gene mutation assay, it cannot be conclusively determined that HHT does not induce gene mutations. Therefore, long-term Pig-a studies are recommended.