Safety and Efficacy Assessments of Isoflavones From Pueraria (Kudzu) Flower Extract in Ovariectomised Mice: A Comparison with Soy Isoflavones

Background/Aims: Numerous foods with function claim are available in Japanese market containing isoflavones derived from pueraria flower extract (PFE). These products are labeled with function claims reducing visceral fat. However, these foods have not undergone proper safety assessment such as estrogenic activity and the effects on drug metabolizing enzymes (cytochrome P-450: CYP) in liver. Therefore, this study evaluated the safety and efficacy of PFE compared with soy isoflavones (ISO) in ovariectomised (OVX) mice. Methods: OVX mice were randomly divided into five groups: OVX control, OVX fed a PFE diet (PFE in human intake), OVX fed a 20PFE diet (PFE in 20-fold human intake), OVX fed an ISO diet (ISO in human intake), and OVX fed a 20ISO diet (ISO in 20-fold human intake). Each group was fed the diet for 28 days. Results: Body, liver, and visceral fat weights were not affected by PFE, 20PFE, ISO, or 20ISO diet in the mice. CYP1A and CYP3A activity and CYP3A11 and CYP3A41 mRNA expression in the liver of the 20ISO-fed mouse were significantly higher than those of the control mice. The ovariectomy-induced bone loss was inhibited by 20ISO diet, but not by PFE diet in OVX mice. Conclusions: These results suggest that (1) PFE intake in human doses had no estrogenic property and did not affect CYP activity in the liver; (2) there was no evidence that PFE affects visceral fat weight in OVX mice.