The influence of a standardized soybean extract (Glycine max) on the expression level of cytochrome P450 genes in vivo.

ABSTRACT

OBJECTIVE: Soybean isoflavones are phytoestrogens that reduce menopausal symptoms and decrease the risk of certain chronic diseases, such as cancer and cardiovascular diseases. Despite the widespread use of soybean isoflavones as functional food and dietary supplements, data regarding the safety as well as herb-drug interactions, remain scarce. The aim of the study was to investigate the influence of soybean extract on the expression levels of cytochrome P450 (CYP) genes using real-time PCR (RT-PCR). MATERIALS AND METHODS: Male Wistar rats were fed a standardized soybean extract containing 37% isoflavones (100 mg/kg) for 3 and 10 days. cDNA was synthesized from total RNA isolated from the liver using reverse transcription. The level of CYP genes expression was analyzed using RT-PCR method. RESULTS: Soybean extract administration resulted in a significant increase of CYP1A1 expression level compared with the control group (1.5-fold; p < 0.05). An inductory effect was also observed for CYP2D1 by 32% (p < 0.01) after 10 days of treatment. No statistically significant differences were noted for CYPIA2, CYP2C6 and CYP3A2. In case of CYP3A1, the mRNA level of this gene was reduced by almost 35% (p < 0.05) both, after 3 and 10 days. CYP2D2 expression was also inhibited by the extract, but to a lesser degree when compared to CYP3A1. Moreover insignificant decrease of CYP2E1 expression level by 25% (p < 0.01) was observed after 3 days of treatment. CONCLUSIONS: These findings suggest that soybean extract may change the expression of CYP enzymes involved in biotransformation of xenobiotics (drugs, procarcinogens).