[Biliary excretion of genistein and its metabolite at different doses in rats].
OBJECTIVE
To study the biliary excretion of genistein and its metabolite at different doses in rats.


METHODS
Suspended in 0.5% CMC-Na solution, genistein was orally administered to rats at the dose of 6.25, 12.5 and 50 mg x kg(-1), separately. At various time intervals, the bile was collected. The bile was treated with beta-glucuronidase. The genistein in bile was extracted twice by vortexing with 2.0 mL mixture of methyl tert-tubtyl ether and pentane (8:2). The organic phase was removed into the tubes and then evaporated in ventilation cabinet. The residue was dissolved in 50 microL of methanol. Twenty microL solution was drawn and detected by high-performance liquid chromatography.


RESULTS
The accumulative biliary excretion of genistein was (42.56 +/- 6.54) , (75.17 +/- 18.87) and (126.60 +/- 34.78) microg at the dose of 6.25, 12.5 and 50 mg x kg(-1), respectively. The total drug (genistein plus glucuronidated genistein) excreted from bile was (108.46 +/- 35.23), (423.46 +/- 158.31) and ( 853.74 +/- 320. 84) microg, and the ratio of glucuronidated genistein was 60.76% , 82.25% and 85.17% at the dose of 6.25, 12.5 and 50 mg x kg(-1), respectively.


CONCLUSIONS
The genistein was excreted mainly in the form of glucuronidated genistein in rat bile. The genistein and glucuronidated genistein were excreted in a nonlinear dose-dependent manner.
Zhou
Si-yuan
SY
Department of Pharmacology, The Fourth Military Medical University, Xi'an 710032, China.
Liu
Xin-you
XY
Teng
Zeng-hui
ZH
Gan
Hong-quan
HQ
Wang
Ru-tao
RT
Yang
Zhi-fu
ZF
Mei
Qi-bing
QB
D000284:Administration, Oral; D000818:Animals; D001646:Bile / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005260:Female; D019833:Genistein / Q000737:chemistry / Q000378:metabolism* / Q000493:pharmacokinetics*; D008297:Male; D015394:Molecular Structure; D048789:Phytoestrogens / Q000008:administration & dosage / Q000378:metabolism / Q000493:pharmacokinetics; D051381:Rats; D017207:Rats, Sprague-Dawley
D048789:Phytoestrogens; D019833:Genistein