ABSTRACT
The aim of this study was to investigate the effects of polyethylene glycol (PEGs) with different molecular weights (MW: 400, 1 000, 4 000) on the pharmacokinetics of baicalin, and preliminarily analyze its mechanism. Rats were gavaged with baicalin (168 mg·kg-1) + aqueous solution or baicalin + PEGs solution and plasma samples were collected from 0 to 24 h after administration. The concentration of baicalin and its main metabolite baicalein 6-O-β-D-glucuronide (B6G) were determined at different time points by UPLC-MS/MS, and the pharmacokinetic parameters were calculated with DAS 3.0 software. The results showed that PEGs with different molecular weights could effectively increase the AUC0-t of baicalin and B6G, increase the Cmax, and prolong the t1/2, effectively increasing the concentration of baicalin and B6G in vivo. The mechanism may be by promoting the activity of uridine diphosphate glucuronosyl-transferases 1A8 (UGT1A8) and 1A9 (UGT1A9), thereby increasing the transformation rate of baicalin and B6G. The rate of metabolism of B6G was faster than that of baicalin, suggesting that PEGs had a higher affinity for UGT1A8, and PEG400 had the most significant effect. The purpose of this study was to provide a basis for the clinical safe use of baicalin and other flavonoids and the design of new dosage forms with the participation of PEGs. The animal experiment protocol in this study was approved by the Experimental Animal Ethics Committee of Guizhou Medical University.
ABSTRACT
Objective:To investigate the effects of polyethylene glycol 400 （PEG400） on the pharmacokinetics and anti-inflammatory effect of baicalin， and to preliminarily explore the anti-inflammatory effects of baicalin and its main metabolite baicalein 6-<italic>O</italic>-<italic>β</italic>-<italic>D</italic>-glucuronide （B6G） by molecular docking. Method:Rats were randomly divided into two groups with water and PEG400 as the dissolving matrix， and rats were administrated the equal dose of baicalin aqueous solution （baicalin+water group） and baicalin PEG400 solution （baicalin+PEG400 group）. After the plasma samples were processed at different time periods， the concentrations of baicalin and B6G in rat plasma were determined by ultra performance liquid chromatography-tandem mass spectrometry （UPLC-MS/MS）， and pharmacokinetic parameters were processed by DAS 3.2.2 software. Mice were randomly divided into a blank group （normal saline， 20 mL·kg<sup>-1</sup>）， aspirin group （dose of 0.2 g·kg<sup>-1</sup>）， baicalin/baicalin+PEG400 high and low dose （3.0， 1.5 g·kg<sup>-1</sup>） groups， after continuous administration for 7 days， the mouse ear swelling and foot swelling models were established， and the swelling degree and swelling inhibition rate were calculated. Result:The pharmacokinetic study showed that compared with baicalin+water group， the plasma concentrations of baicalin and B6G increased after administration of baicalin PEG400 solution， and the area under the curve （AUC<sub>0-</sub><italic><sub>t</sub></italic>） increased by 2.36， 1.97 times， and the peak concentration （<italic>C</italic><sub>max</sub>） increased by 2.12， 1.65 times， respectively. The results of mouse ear and foot swelling inflammation models showed that the anti-inflammatory effect was enhanced after intragastric administration of baicalin PEG400 solution. In addition， molecular docking results showed that baicalin and B6G could site bind to multiple target proteins ［tumor necrosis factor （TNF）-<italic>α</italic>， interleukin （IL）-6， IL-1<italic>β</italic>， prostaglandin E<sub>2</sub> （PGE<sub>2</sub>） and nuclear transcription factor-<italic>κ</italic>B （NF-<italic>κ</italic>B）］ with higher affinity， which was superior to the positive drug aspirin. Conclusion:PEG400 can increase the plasma concentration of baicalin and its main metabolite B6G， and enhance the anti-inflammatory effect. Baicalin and B6G can form strong hydrogen bonds with various inflammatory factors and of nuclear transcription factors， it is speculated that baicalin and B6G jointly play an anti-inflammatory role.