ABSTRACT: To study the metabolic and pharmacokinetic profile of scutellarin, an active component from the medical plant Erigeron breviscapus (Vant) Hand-Mazz, and to investigate the mechanisms underlying the low bioavailability of scutellarin though oral or intravenous administration in rats.
HPLC method was developed for simultaneous detection of scutellarin and scutellarein (the aglycone of scutellarin) in rat plasma, urine and feces. The in vitro metabolic stability study was carried out in rat liver microsomes from different genders.
After a single oral dose of scutellarin (400 mg/kg), the plasma concentrations of scutellarin and scutellarein in female rats were significantly higher than in male ones. Between the female and male rats, significant differences in AUC, t(max2) and C(max2) for scutellarin were found. The pharmacokinetic parameters of scutellarin in the urine also showed significant gender differences. After a single oral dose of scutellarin (400 mg/kg), the total percentage excretion of scutellarein in male and female rats was 16.5% and 8.61%, respectively. The total percentage excretion of scutellarin and scutellarein in the feces was higher with oral administration than with intravenous administration. The in vitro t(1/2) and CL(int) value for scutellarin in male rats was significantly higher than that in female rats.
The results suggest that a large amount of ingested scutellarin was metabolized into scutellarein in the gastrointestinal tract and then excreted with the feces, leading to the extremely low oral bioavailability of scutellarin. The gender differences of pharmacokinetic parameters of scutellarin and scutellarein are due to the higher CL(int) and lower absorption in male rats.
Acta Pharmacologica Sinica 05/2011; 32(5):655-63. · 1.95 Impact Factor
ABSTRACT: Aim: To study the metabolic and pharmacokinetic profile of scutellarin, an active component from the medical plant Erigeron breviscapus (Vant) Hand-Mazz, and to investigate the mechanisms underlying the low bioavailability of scutellarin though oral or intravenous administration in rats.
Acta Pharmacologica Sinica 04/2011; 32(5):655-663. · 1.95 Impact Factor
ABSTRACT: To investigate the absorption and transepithelial transport characteristics of scutellarin and scutellarein in the human colonic adenocarcinoma cell (Caco-2) monolayer model. The influence factors on these two compounds' absorption were investigated, such as buffer solution, duration of culture, and inhibitors of multidrug resistance-associated protein 2 (MRP(2)), breast cancer drug resistance protein (BCRP) and P-glycoprotein (P-gp).
By using Caco-2 monolayer as an intestinal epithelial cell model, the transport process was studied from apical (AP) side to basolateral (BL) side or from BL to AP. The two compounds were determined by high-performance liquid chromatography coupled with diode-array-detector detection. Transport parameters and apparent permeability coeffients (P(app)) were calculated.
The P(app) values of scutellarin and scutellarein were different in two buffer solutions, respectively. In phosphate buffered saline, scutellarin had no absorption from AP to BL, while its P(app) value was 0.74×10(-6) to 1.58×10(-6) cm/s from BL to AP. The P(app) values of scutellarein were 4.33×10(-6) to 6.79×10(-6) cm/s and 1.32×10(-6) to 2.56×10(-6) cm/s from AP to BL and from BL to AP, respectively. The P(app) value gradually decreased with time. The absorption of scutellarein was better than that of scutellarin. The scutellarin absorption was improved by verapamil, MK-571 and reserpine. The scutellarein absorption was improved by verapamil whereas its excretion was improved by MK-571.
Absorption of scutellarin is difficult in Caco-2 monolayer cells, which contributes to its low bioavailability. Scutellarein absorption is better than scutellarin absorption. Scutellarein transepithelial transport is passive diffusion. The inhibitor of P-gp can improve scutellarin and scutellarein transportation. The inhibitors of MRP(2) and BCRP can promote transportation of scutellarin. The inhibitor of MRP(2) can promote efflux of scutellarein. The multidrug resistance-associated protein may be the second reason for low bioavailability of scutellarin.
Journal of Chinese Integrative Medicine 09/2010; 8(9):863-9.