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To study on the effects of Achyranthes bidentata on Tongsaimai pellets main active ingredients chlorogenic acid, isoliquiritin, harpagoside and glycyrrhizin in rats in vivo pharmacokinetic behaviors, a method for the simultaneous determination of chlorogenic acid, isoliquiritin, harpagoside and liquiritigenin in rat plasma was established by UPLC-MS/MS. The analysis was performed on a waters Acquity BEH C18 column (2.1 mm x 100 mm, 1.7 microm) with the mixture of acetonitrile and 0.1% formic acid/water as mobile phase, and the gradient elution at a flow rate of 0.3 mL x min(-1). The analytes were detected by tandem mass spectrometry with the electrospray ionization (ESI) source and in the multiple reaction monitoring (MRM) mode. It turned out that the analytes of Tongsaimai pellets groups C(max) and AUC(Q-infinity) values were higher than that with A. bidentata group, and the C(max) values of chlorogenic acid had significantly difference (P < 0.05), the AUC(0-infinity) values of chlorogenic acid and glycyrrhizin had significantly difference (P < 0.05); The T(max) and CL values of two groups had no significantly difference. Results showed that the established method was specific, rapid, accurate and sensitive for the studies of Tongsaimai pellets four main active ingredients in rat in vivo pharmacokinetic, and A. bidentata have varying degrees of effects on Tongsaimai pellets four main active ingredients in rat in vivo pharmacokinetic behaviors.

Glycosides are important active components in traditional Chinese medicine (TCM). Their pharmacological activity, pharmacokinetic characteristics and in vivo existence become hotspots of current studies. The metabolic pathways of these glycosides are de-glycosylation mainly mediated by gut microbiota. After glycosides were metabolized into aglycones, they could be absorbed more easily and show better pharmacological effects. In this article, we reviewed the main glycosidase in gut microbiota which helps metabolize TCM glycosides, relevant bacterial strains which generate glycosidase, as well as the de-glycosylated metabolic pathways of the representative glycosides, on the basis of gut microbiota's important roles in in vivo metabolism and efficacy of TCM glycosides. We also preliminarily solved problems in studies on de-glycosylation of TCM glycosides.

Forsythoside A (FTA), one of the main active ingredients in weeping forsythia extract, possesses strong antibacterial, antioxidant and antiviral effects, and its content was about 8% of totally, higher largely than that of other ingredients, but the absolute bioavailability orally was approximately 0.5%, which is significant low influencing clinical efficacies of its oral preparations. In the present study, in vitro Caco-2 cell, in situ single-pass intestinal perfusion and in vivo pharmacokinetics study were performed to investigate the effects of absorption enhancers based on tight junctions: sodium caprate and water-soluble chitosan on the intestinal absorption of FTA, and the eventual mucosal epithelial damage resulted from absorption enhancers was evaluated by MTT test, measurement of total amount of protein and the activity of LDH and morphology observation, respectively. The pharmacological effects such as antioxidant activity improvement by absorption enhancers were verified by PC12 cell damage inhibition rate after H₂O₂ insults. The observations from in vitro Caco-2 cell showed that the absorption of FTA in weeping forsythia extract could be improved by absorption enhancers. Meanwhile, the absorption enhancing effect of water-soluble chitosan may be almost saturable up to 0.0032% (w/v), and sodium caprate at concentrations up to 0.64 mg/ml was safe for the Caco-2 cells, but water-soluble chitosan at different concentrations was all safe for these cells. The observations from single-pass intestinal perfusion in situ model showed that duodenum, jejunum, ileum and colon showed significantly concentration-dependent increase in P(eff)-value, and that P(eff)-value in the ileum and colon groups, where sodium caprate was added, was higher than that of duodenum and jejunum groups, but P(eff)-value in the jejunum group was higher than that of duodenum, ileum and colon groups where water-soluble chitosan was added. Intestinal mucosal toxicity studies showed no significant toxicity below 800 μg/ml sodium caprate and water-soluble chitosan at different concentrations. In pharmacokinetics study, water-soluble chitosan at dosage of 50mg/kg improved the bioavailability of FTA in weeping forsythia extract to the greatest extent, and was safe for gastrointestine from morphological observation. Besides, treatment with weeping forsythia extract with water-soluble chitosan at dosage of 50 mg/kg prevented PC12 cell damage upon H₂O₂ stimulation better than that of control. All findings above suggested that water-soluble chitosan at dosage of 50 mg/kg might be safe and effective absorption enhancer for improving the bioavailability of FTA and the antioxidant activity in vivo in weeping forsythia extract., (Copyright © 2012 Elsevier GmbH. All rights reserved.)

Aim: To investigate the mechanisms underlying the intestinal absorption of the major bioactive component forsythoside A (FTA) extracted from Forsythiae fructus., Methods: An in vitro Caco-2 cell model and a single-pass intestinal perfusion in situ model in SD rats were used., Results: In the in vitro Caco-2 cell model, the mean apparent permeability value (P(app)-value) was 4.15×10(-7) cm/s in the apical-to-basolateral (AP-BL) direction. At the concentrations of 2.6-10.4 μg/mL, the efflux ratio of FTA in the bi-directional transport experiments was approximately 1.00. After the transport, >96% of the apically loaded FTA was retained on the apical side, while >97% of the basolaterally loaded FTA was retained on the basolateral side. The P(app)-values of FTA were inversely correlated with the transepithelial electrical resistance. The paracellular permeability enhancers sodium caprate and EDTA, the P-gp inhibitor verapamil and the multidrug resistance related protein (MRP) inhibitors cyclosporine and MK571 could concentration-dependently increase the Papp-values, while the uptake (OATP) transporter inhibitors diclofenac sodium and indomethacin could concentration-dependently decrease the P(app)-values. The intake transporter SGLT1 inhibitor mannitol did not cause significant change in the P(app)-values. In the in situ intestinal perfusion model, both the absorption rate constant (K(a)) and the effective permeability (P(eff)-values) following perfusion of FTA 2.6, 5.2 and 10.4 μg/mL via the duodenum, jejunum and ileum had no significant difference, although the values were slightly higher for the duodenum as compared to those in the jejunum and ileum. The low, medium and high concentrations of verapamil caused the largest increase in the P(eff)-values for duodenum, jejunum and ileum, respectively. Sodium caprate, EDTA and cyclosporine resulted in concentration-dependent increase in the P(eff)-values. Diclofenac sodium and indomethacin caused concentration-dependent decrease in the Peff-values. Mannitol did not cause significant change in the P(app)-values for the duodenum, jejunum or ileum., Conclusion: The results suggest that the intestinal absorption of FTA may occur through passive diffusion, and the predominant absorption site may be in the upper part of small intestine. Paracellular transport route is also involved. P-gp, MRPs and OATP may participate in the absorption of FTA in the intestine. The low permeability of FTA contributes to its low oral bioavailability.

Shuang-Huang-Lian (SHL), a traditional Chinese formula containing Lonicerae japonicae flos (LJF), Scutellariae radix (SR) and Forsythiae fructus (FF), is commonly used to treat acute upper respiratory tract infection, acute bronchitis and light pneumonia. Forsythoside A is one of the main active ingredients in Forsythiae fructus, a key herb in SHL. In the present study, effects of different compositions in SHL on the in vitro metabolism in Sprague-Dawley rat liver microsomes of forsythoside A were investigated. The observations from Sprague-Dawley rat liver microsomes in the presence of β-NADPH or UDPGA that forsythoside A may be the substrates of CYP3A4, CYP2C9, CYP1A2, UGT1A6, UGT1A3, UGT1A1 and UGT1A9; Chlorogenic acid may be the substrates of CYP3A4, CYP2C9, CYP1A2, CYP2C19, UGT1A6, UGT1A3 and UGT1A1; Baicalin may be the substrates of CYP3A4, CYP2C19, CYP1A2, UGT1A9, UGT1A1 and UGT1A3; Baicalein may be the substrates of CYP3A4, CYP2E1 and UGT1A6. It was also found that the residue of forsythoside A in SHL, FF+LJF and FF+SR was greatly increased compared with that in FF in Sprague-Dawley rat liver microsomes in the presence of β-NADPH or UDPGA, which indicated that the metabolism of forsythoside A in SHL may be influenced by chlorogenic acid in LJF acting on the CYP3A4, CYP2C9, CYP1A2, UGT1A6, UGT1A3 and UGT1A1; baicalin in SR acting on the CYP3A4, CYP1A2, UGT1A9, UGT1A1 and UGT1A3; baicalein acting on the CYP3A4 and UGT1A6 respectively., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Shuang-Huang-Lian (SHL), a traditional Chinese formula containing Lonicerae japonicae flos (LJF), Scutellariae radix (SR) and Forsythiae fructus (FF), is commonly used to treat acute upper respiratory tract infection, acute bronchitis and light pneumonia. Forsythoside A is one of the main active ingredients in Forsythiae fructus, a key herb in SHL. In the present study, effects of different compositions in SHL on the intestinal absorption of forsythoside A were investigated. The observations from in situ intestinal circulation model showed that A/%(h(-1)) of forsythoside A in FF+LSF, FF+SR and SHL were all reduced greatly compared with that in FF. However, in pharmacokinetics study, C(max) and AUC(0→1440) of forsythoside A all increased and T(1/2) prolonged in SHL, FF+LJF and FF+SR compared with FF. The results indicated that the different compositions of SHL decreased absorption but increased bioavailability of forsythoside A, which may be related to its metabolism inhibited in intestine or liver., (Copyright © 2010 Elsevier B.V. All rights reserved.)

This study is to investigate the effects of concentration, intestinal section, pH, paracellular route, substrate/inhibitor of enzyme (CYP3A) and proteins (P-gp, MRP2, SGL1) on the absorption of forsythoside A. The absorption of three concentrations (2.6, 5.2, and 10.4 microg x mL(-1)) of forsythoside A in different intestinal segments was studied with phenol red as the marker by rat circulation in situ. The results showed that the residue of forsythoside A with different concentrations had little significant difference from that obtained after perfusing via duodenum, jejunum, ileum and colon, which indicated that the absorption of forsythoside A was passive diffusion and had no difference in different segments of rat intestine. The residue of forsythoside A increased to 466.160 and 463.429 microg respectively when cyclosporine (4 microg x mL(-1)) or midazolam (50 micromol x L(-1)) was added to the circulation fluid, which showed significant difference compared to the control group (P < 0.05). Moreover, the residue of forsythoside A showed a tendency of increase with the increase of cyclosporine or midazolam. When digoxin (50 micromol x L(-1)) or EDTA (10 microg x mL(-1)) was added to the circulation fluid, the residue of forsythoside A decreased to 325.110 and 369.888 microg respectively, which showed significant difference as compared to the control group (P < 0.05). Besides, the residue of forsythoside A showed a tendency of reduction with the increase of digoxin or EDTA. However, there is no significant change in the absorption of forsythoside A when the different concentrations of mannitol were added to the circulation fluid. The results above indicated that the absorption of forsythoside A was mainly passive diffusion and involved paracellular route at the same time. In addition, the substrates of P-gp or CYP3A had dose-dependent effect on the absorption of forsythoside A.