In April 2015, “Foods with Functional Claims (FFCs)” was established as a new category of labeling in health food products sold in Japan, and we have already found some FFCs with poor-quality for functional component level. To ensure the efficacy and safety of the FFCs, effective quality control on the validity of the original plants, the consistency of components, and manufacturing process is important for the herbal ingredients with specific health-related functions in FFCs. In this study, we evaluated the amount of isoflavones in 8 FFCs of which functional components are Puerariae thomsonii flower-derived isoflavones (as tectorigenin derivatives). These FFCs contained 39.9 ~ 49.0 mg/day of tectorigenin derivatives (sum of tectorigenin 7-O-(6-O-xylosylglucoside), tectoridin, and tectorigenin), corresponding to 106 ~ 117% of the labeled values within a small margin of error. This result indicated that the tested FFCs have as high quality as herbal medicinal products for the chemical component level. Additionally, the aglycone content (tectorigenin equivalents) in 8 FFCs ranged from 25 to 31 mg/day. Since tectorigenin derivatives is thought to have strong estrogenic effects even though their binding affinities for estrogen receptors are weak, further investigation and discussion would be needed for ensuring the efficacy and safety of FFCs containing Puerariae thomsonii flowerderived isoflavones.
