Toxicological Characterization of Polyporus umbellatus Extract: Genotoxicity and 2-Week Repeated-Dose Toxicity Study

Polyporus umbellatus is a traditional medicinal fungus with potential application as a food-related bioactive; however, toxicological data for concentrated extracts remain limited. This study evaluated aqueous P. umbellatus extract using three complementary genotoxicity assays and a 2-week repeated-dose toxicity study. Genotoxicity was assessed using an in vitro chromosomal aberration assay in Chinese hamster lung cells, a bacterial reverse mutation assay, and an in vivo bone marrow micronucleus assay. The repeated-dose toxicity study was performed in F344 rats administered 500, 1000, or 2000 mg/kg/day P. umbellatus extract by oral gavage for 2 weeks. P. umbellatus extract significantly increased structural chromosomal aberrations in vitro under short-term treatment with metabolic activation, and under short-term and continuous-treatment conditions without metabolic activation. In contrast, the extract did not increase revertant colonies of Salmonella typhimurium or Escherichia coli tester strains, and oral administration did not increase micronucleated polychromatic erythrocytes in male or female ICR mice. Repeated oral administration for 2 weeks caused no mortality, treatment-related clinical signs, body weight loss, gross lesions, or consistent hematological or serum biochemical toxicity patterns. Isolated changes in male kidney weight, female salivary gland weight, and male creatine kinase activity were not accompanied by concordant findings and were therefore not interpreted as definitive adverse effects. Overall, the findings indicate an in vitro clastogenic response without evidence of bacterial mutagenicity, bone marrow micronucleus induction, or overt repeated-dose oral toxicity under the investigated experimental conditions, paving the way for long-term studies to complete the toxicological characterization of P. umbellatus.