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.
ABSTRACT
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.
ABSTRACT
OBJECTIVE：To isolate and purify baicalin metabolites from rat bile ，and to study its effect on the proliferation of liver cancer HepG 2 cells. METHODS ：Totally of 6 SD rats were collected ，anesthetized and then intubated with bile ducts. They were given baicalin （168 mg/kg）intragastrically after the rats were awake as well as the bile sample 1 was collected during 24 h after intragastric administration. After processed ，bile sample 1 was preliminarily analyzed by HPLC. Another 5 SD rats were anesthetized and intubated in the same way as above ，and then given baicalin intragastrically （400 mg/kg）. The bile sample 2 was collected during 48 h after intragastric administration. After processed ，the bile sample 2 was isolated and purified by semi-preparative HPLC. The isolated metabolites were identified by using UV ，IR，MS and NMR ，as well as based on physical and chemical properties. MTT method combined with high content cell imaging analysis system was used to study the effect of the metabolites on the proliferation of HepG 2 cells. RESULTS ：Baicalin was mainly metabolized into metabolite 1 and metabolite 2 through bile. After isolation and purification ， they were identified as oroxylin A- 7-O-β-D-glucuronide and 2726719792@qq.com baicalein 6-O-β-D-glucuronide. The results of MTT assay showed that the metabolite 2 had a significant inhibitory effect 分析。E-mail：gaoxl@gmc.edu.cn on the proliferation of HepG 2 cells，and its IC 50 was 90 µg/mL；the results of high content cell imaging analysis showed that at a certain concentration metabolite 2 may inhibit proliferation by changing the mitochondrial distribution and membrane permeability of HepG 2 cells（studies on the pharmacological activities of metabolism 1 had been reported ，it was skipped in this study ）. CONCLUSIONS ：In this study ，two baicalin bile metabolites were successfully isolated and identified ，of which baicalein 6-O-β-D-glucuronide has a significant inhibitory effect on the proliferation of HepG 2 cells.