Studies On The Oral Absorption Characteristics And Pharmacokinetics Of Polygonum Capitatum

Objective: To develop a sensitive ultra performance liquid chromatography electrospray ionization tandem mass sepctrometry(UPLC-ESI-MS/MS) method for analyzing main components of biological samples(i.e., cell lysate soluton, intestine perfusion solution, and rat plasma); and to simultaneously evaluate the absorpted components, absorption mechanism, influence factors and pharmacokinetic(PK) characteristics of the main components of P. capitatum extract. Methods: The absorpted components were comfirmed with the Caco-2 cell model, and the effect of concentration, temperature, p H on cellular uptake were further investigated. The absorption of these compounds were determined at different intestinal segments of rats. The influences of drug concentration and P-gp inhibitors were evaluated using in situ perfusion method in rats. Concentrations of three components were determined at different time points after oral administration P. capitatum extract. The main pharmacokinetic parameters of gallic acid, protocatechuie acid and quercitrin were obtained based on the analysis of the plasma sample. Results: The method were in accordance with technical principle promulgated. Results proved that the amount of cell uptake depended on concentrations, time and temperature. The absorption mechanism of the six ingredients complied with the passive diffusion(r2>0.9). The amount of cell uptake of protocatechuie acid were decreased along with time. Saturation phenomenon occurred in high dosage such as gallic acid, protocatechuie acid, myricetrin and quercitrin. The absorption of protocatechuic acid significantly increased and the myricetrin, hirsutrin significantly dicreased without bile duct being ligated. Further more, protocatechuic acid increased significantly by P-gp inhibitors, it indicated that protocatechuic acid was the substrates of P-gp. The results proved that five components absorbed more in small intestine than in colon. After oral administration of P. capitatum extract, gallic acid, protocatechuie acid and quercitrin were quickly absorbed and accorded with pharmacokinetic model of two-room. Tmax were 0.5~1.7 h, MRT0-t were 2.88~4.52 h, AUC(0-t) were 1.07~72.48 mg/L*h. The double peak feature was observed by the drug concentration-time curve of quercitrin. Conclusion: A rapid, selective and sensitive UPLC–MS/MS method was established and validated for the quantification of gallic acid, protocatechuie acid, myricetrin, hirsutrin, quercitrin and quercetin in the biological samples. The experiments preliminarily elucidated the mechanism and influence factors of absorptions of the six components in P. capitatum extract and obtained the main pharmacokinetic parameters of gallic acid, protocatechuie acid and quercitrin. Different absorption models were compared and their relevance to human absorption discussed at the integral, organ and cellular levels, which provided a theoretical and experimental foundation for the new drug development of P. capitatum.