Flavonoid Pharmacokinetics and Tissue Distribution after Repeated Dosing of the Roots ofScutellaria baicalensisin Rats

Abstract

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 After the 7th dose, blood samples were withdrawn at specific times and organs, including the liver, kidney, lung, and brain, and collected.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.

Steady-state pharmacokinetics and tissue distribution of anthraquinones of Rhei Rhizoma in rats

“…The only free form found in the circulation was rhein, which also presented mainly as its glucuronides/sulfates (Shia et al, 2009). Later, another our study reporting the tissue distribution of flavonoids of Scutellariae Radix (root of Scutellariae baicalensis) disclosed that the free forms of baicalein and wogonin were the major forms in many organs, in contradiction to the finding in blood (Hou et al, 2011). Therefore, in order to elucidate the real molecular forms and concentrations of rhubarb anthraquinones in the circulation and in various organs at the steady state, pharmacokinetic and tissue distribution studies following repeated dosing of RP decoction were conducted in rats.…”

Baicalein attenuates renal fibrosis by inhibiting inflammation via down-regulating NF-κB and MAPK signal pathways

“…Therefore, suppressing inflammatory response could attenuate renal fibrosis. Baicalein (5,6,7-trihydroxyflavone) is a natural flavonoid extracted from the Chinese herb Scutellaria baicalensis (Hou et al 2011). It has been widely used as a therapeutic agent for microbial infection in East Asian countries.…”

Detection of Baicalin Metabolites Baicalein and Oroxylin-A in Mouse Pancreas and Pancreatic Xenografts

“…There have been a number of pharmacokinetics studies to investigate absorption of BG and B. 8–11 Akao et al compared in vivo absorption of BG and B in regular rats to that in germ-free rats and suggested that BG underwent intestinal conversion to B, which is absorbed rapidly and converted back to BG in the systemic circulation. 11 An in situ absorption experiment revealed the existence of double-site absorption of BG.…”