Investigation of Effect of Polyethylene Glycol 400 on Pharmacokinetics and Anti-inflammatory Effect of Baicalin Based on UPLC-MS/MS and Molecular Docking Techniques / 中国实验方剂学杂志

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^-1）， aspirin group （dose of 0.2 g·kg^-1）， baicalin/baicalin+PEG400 high and low dose （3.0， 1.5 g·kg^-1） 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_0-<italic>_t</italic>） increased by 2.36， 1.97 times， and the peak concentration （<italic>C</italic>_max） 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 E₂ （PGE₂） 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.

Effect of Polyethylene Glycol 400 on Bile Excretion of Baicalin and Its Main Metabolite / 中国实验方剂学杂志

Objective::To investigate the effect of polyethylene glycol 400 (PEG400) on rat bile excretion of baicalin and its main metabolite [baicalein 6-O-β-D-glucuronide (B6G)], and to analyze its mechanism of action. Method::Rats were randomly divided into baicalin+ water group and baicalin+ PEG400 group, the anesthesia was induced by intraperitoneal injection of 10% chloral hydrate (dose of 4 mL·kg-1) to prepare a rat bile duct intubation model. After the rats were fully awake, rats were given baicalin aqueous solution and baicalin PEG400 solution with dose of 168 mg·kg-1 for baicalin, respectively. And bile was collected from 0 h to 12 h after administration. UPLC-MS/MS was used to determine the concentration of drug excreted through bile at different time periods. Thermo Hypersil GOLD C18 column was used with acetonitrile (A)-0.1% formic acid solution (B) as the mobile phase for gradient elution (0-9 min, 90%-27%B; 9-10 min, 27%-90%B; 10-12 min, 90%B), the flow rate was 0.3 mL·min-1, the column temperature was 30 ℃, the injection volume was 5 μL. The mass spectra were obtained in positive ion mode with electrospray ionization (ESI). The effects of PEG400 on the activities and expressions in rat liver of uridine diphosphate glucuronyltransferase (UGT) 1A8 and UGT1A9 were studied in vitro incubation assay and enzyme linked immunosorbent assay (ELISA). Result::Compared with the baicalin+ water group, in the baicalin+ PEG400 group, the bile cumulative excretions of baicalin and B6G increased by 1.8 times and 2.1 times within 12 h, respectively. PEG400 increased the enzyme activities of UGT1A8 and UGT1A9 by 2.0 times and 1.5 times, and their concentrations in liver were increased by 2.2 times and 1.3 times, respectively. Conclusion::PEG400 can significantly increase the bile excretion of baicalin and its main metabolite B6G by enhancing the activities and expressions of UGT1A8 and UGT1A9, and its promoting effect on bile excretion of B6G is greater than that of baicalin, which provides a basis for the rational clinical application of PEG400 and the design of new dosage forms of flavonoids such as baicalin.