Quercetin and Rutin are most common flavone constituents of some herb extracts such as Hippophae rhamnoides L. Inter and intra herb pharmacokinetics interactions of Quercetin and Rutin were investigated in the present study. Pharmacokinetic study was investigated in the two groups of rats (n = 6) for pharmacokinetic interactions between the Quercetin and Rutin (2.5 mg/kg) mixture treated alone with European patented polyherbal formulation containing equivalent weight of the above. The total plasma concentrations of Quercetin and Rutin were determined by liquid chromatography mass spectrometry (LC-MS). A method was developed and validated according to the ICH guidelines. The results of the present study shows that there are great differences in the pharmacokinetics of Quercetin and Rutin when they are administered together and from the polyherbal formulation which will be interacted by many other constituents. The bioavailability of Quercetin was lowered from the polyherbal formulation when compared with the co-administration, whereas the Rutin bioavailability has increased from the polyherbal formulation when compared with the co-administration. The maximum plasma concentration of Quercetin from coadministration and polyherbal formulation was 165.3 ± 31.9 and 90.8 ± 21.4 ng/mL, respectively, whereas in the case of Rutin it was 61.1 ± 29.3 and 121.7 ± 19.2 ng/mL. After polyherbal formulation administration to rats the AUC0-24, AUC0-∞ and AUMC0-∞ of both Quercetin and Rutin significantly increased when compared to co-administration. The above results proved that inter and intra herb pharmacokinetic interactions between Quercetin and Rutin. Possible interactions of the other constituents with hydrolyzing enzymes in the formulation enhances the oral bioavailability of Rutin. Accordingly besides the drug herb interactions, inter and intra herb interaction might be brought into view with the wide use of herbal remedies.

Abstract. The US patented polyherbal formulation for the prevention and management of type II diabetes and its vascular complications was used for the present study. The xanthone glycoside mangiferin is one of the major effector constituents in the Salacia species with potential anti-diabetic activity. The pharmacokinetic differences of mangiferin following oral administration of pure mangiferin and polyherbal formulation containing Salacia species were studied with approximately the same dose 30 mg/kg mangiferin and its distribution among the major tissue in Wistar rats. Plasma samples were collected at different time points (15, 30, 60, 120, 180, 240, 360, 480, 600,1,440,2,160, and 2880 min) and subsequently analyzed using a validated simple and rapid LC-MS method. Plasma concentration versus time profiles were explored by non-compartmental analysis. Mangiferin plasma exposure was significantly increased when administered from formulation compared to the standard mangiferin. Mangiferin resided significantly longer in the body (last mean residence time (MRT last )) when given in the form of the formulation (3.65 h). C max values of formulation (44.16 μg/mL) administration were elevated when compared to equivalent dose of the pure mangiferin (15.23 μg/mL). Tissue distribution study of mangiferin from polyherbal formulation was also studied. In conclusion, the exposure of mangiferin is enhanced after formulation and administration and could result in superior efficacy of polyherbal formulation when compared to an equivalent dose of mangiferin. The results indicate that the reason which delays the elimination of mangiferin and enhances its bioavailability might the interactions of the some other constituents present in the polyherbal formulation. Distribution study results indicate that mangiferin was extensively bound to the various tissues like the small intestine, heart, kidney, spleen, and liver except brain tissue.

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