Flavonoid pharmacokinetics and tissue distribution after repeated dosing of the roots of Scutellaria baicalensis in rats.
Scutellariae Radix (root of Scutellaria baicalensis, SR) contains numerous flavonoids such as baicalin, baicalein, and wogonin. This study investigated the pharmacokinetics and tissue distribution of flavonoids and their metabolites in rats after repeated dosing of a SR decoction. Sprague-Dawley rats were orally administered SR at 2 g/kg for seven doses. After the 7th dose, blood samples were withdrawn at specific times and organs, including the liver, kidney, lung, and brain, and collected. The concentrations of baicalein and wogonin in the serum and various tissues were assayed by HPLC before and after hydrolysis with glucuronidase and sulfatase. Baicalein and wogonin were not detected in the serum, and the molecules found were their glucuronides/sulfates. In tissues, the free forms of baicalein and wogonin appeared in the liver, kidney, and lung in addition to their glucuronides/sulfates. Baicalein was the major form in the lung, whereas baicalein glucuronides/sulfates were the major forms in the liver and kidney. Wogonin was the major form in the liver, kidney, lung, and traces of wogonin glucuronides/sulfates were detected in the kidney and liver. Neither baicalein and wogonin nor their glucuronides/sulfates were detected in the brain. In conclusion, the glucuronides/sulfates of baicalein and wogonin were exclusively present in the circulation, whereas their free forms appeared in the lung, liver, and kidney.
Hou
Yu-Chi
YC
School of Pharmacy, College of Pharmacy, China Medical University, Taichung, Taiwan.
Lin
Shiuan-Pey
SP
Tsai
Shang-Yuan
SY
Ko
Miau-Hwa
MH
Chang
Yun-Chia
YC
Chao
Pei-Dawn Lee
PD
D000284:Administration, Oral; D000818:Animals; D001921:Brain / Q000378:metabolism; D002853:Chromatography, Liquid; D004365:Drugs, Chinese Herbal / Q000008:administration & dosage / Q000493:pharmacokinetics; D044950:Flavanones / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000652:urine; D005419:Flavonoids / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000652:urine*; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008168:Lung / Q000378:metabolism; D008297:Male; D010936:Plant Extracts / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000652:urine; D018517:Plant Roots / Q000737:chemistry; D051381:Rats; D017207:Rats, Sprague-Dawley; D031364:Scutellaria baicalensis / Q000737:chemistry*; D053719:Tandem Mass Spectrometry; D014018:Tissue Distribution
D004365:Drugs, Chinese Herbal; D044950:Flavanones; D005419:Flavonoids; D010936:Plant Extracts; C499814:Scutellaria baicalensis extract; C038044:baicalin; C006680:baicalein; C085514:wogonin