Metabolism of Daidzein by Fecal Bacteria in Rats

摘要

Daidzein(4',7-dihydroxyisoflavone),asoyphytoestrogen,isaweaklyestrogeniccompoundthatmayhavepotentialhealthbenefits.Biotransformationofdaidzeinbythehumangutmicrofloraafteringestionconvertsittoeitherthehighlyestrogenicmetaboliteequolortononestrogenicmetabolites.Weinvestigatedthemetabolismofdaidzeinbycolonicmicrofloraofrats.Fecalsamples,obtainedbeforeandafterratswereexposedtodaidzeinat250or1000partspermillion,wereincubatedinbrain-heartinfusion(BHI)brothwithdaidzeinunderanaerobicconditions.Sampleswereremovedfromtheculturesdailyandanalyzedbyhigh-performanceliquidchromatography(HPLC)andmassspectrometry.Thefecalbacteriaofallrats,regardlessofpriordaidzeinexposure,metabolizedtheaddeddaidzeintodihydrodaidzein.BothcompoundsdisappearedrapidlyfromBHIculturesincubatedformorethan24h,butnootherdaidzeinmetabolitesweredetected.Onlydaidzeinanddihydrodaidzeinwerefoundinadirectanalysisofthefecesofratsthathadconsumeddaidzeinintheirdiets.Unlikethefecalbacteriaofhumansandmonkeys,theratflorarapidlymetabolizeddaidzeintoaliphaticcompoundsthatcouldnotbedetectedbyHPLCormassspectralanalysis.