Guo-Wei Zhao

Correlation between synergistic action of Radix Angelica dahurica extracts on analgesic effects of Corydalis alkaloid and plasma concentration of dl-THP.

AIM OF STUDY Yuanhu Zhitong prescription that consists of Corydalis yanhusuo and Radix Angelicae dahuricae has been used for the treatment of gastralgia, costalgia, headache and dysmenorrhea in Traditional Chinese Medicine. Our previous studies demonstrated that Corydalis alkaloid (CA, derived from the root of Corydalis yanhusu) had potent analgesic properties, and the total coumarins of Angelica dahurica (Cou) and volatile oil (VO) that derived from the root of Radix Angelicae dahuricae all could increase the analgesic effect of CA. The major objective of this paper was to investigate the mechanism that leading the analgesia of CA increased by Cou and (or) VO. MATERIALS AND METHODS The relationship between analgesic effect of CA and the plasma concentration of Dl-tetrahydropalmatine (dl-THP, active component of CA) was assayed in mice writhing test. The CA (34, 68 and 134 mg/kg) reduced the nociception by acetic acid intraperitoneal injection in a dose-dependent manner, and there was a significant linear relationship between the analgesic effect of CA and the plasma concentration of dl-THP. Then the plasma concentration of dl-THP at different time intervals in rats after oral administration of CA, CA-Cou, CA-VO and CA-Cou-VO were examined by using HPLC. RESULTS AND CONCLUSION The results indicated that Cou and (or) VO raised the plasma concentration of dl-THP prominently. In conclusion, the reason that Radix Angelica dahurica extracts reinforced the analgesic effects of Corydalis alkaloid was related to the improvement of the plasma concentration of dl-THP.

Transport properties of puerarin and effect of Radix Angelicae Dahuricae extract on the transport of puerarin in Caco-2 cell model.

ETHNOPHARMACOLOGICAL RELEVANCE Angelicae Dahurica (Hoffm.)Benth.& Hook.f.ex Franch.&Sav combined with Pueraria labota (Willd.)Ohwi has been widely used as herb-pairs in traditional Chinese medicine (TCM) for utilization of antipyretic analgesic and anti-inflammatory drugs, and modern pharmacological studies have shown that application compatibility of the two drugs has the effects of cardiovascular disease treatment. The previous study has proved that Radix Angelicae Dahuricae extract could enhance the intestinal absorption of puerarin in Pueraria. But the underlying compatibility mechanism of the two herbs remains unknown. In this study we tried to further evaluate the improvement of Radix Angelicae Dahuricae extract on the puerarin using the Caco-2 cell model and explore the transport properties of puerarin through the above research to discuss the possible effect mechanism of Radix Angelicae Dahuricae extract on the transport of puerarin and the underlying compatibility mechanism of the two herbs. AIM OF STUDY The aim of this work was to study the transport properties of puerarin in Radix Pueraria across Caco-2 cell membrane and to explore how the Radix Angelicae Dahuricae extract affected the transport of puerarin using the well-characterized, human-based intestinal Caco-2 cell model as a platform. MATERIALS AND METHODS The bidirectional transport, and the effects of time, drug concentration, pH, P-gp inhibitors (Verapamil, Cyclosporin A), MRP inhibitor (MK-571) and EDTA-Na(2) (tight junction modulator) on the absorption of puerarin were observed. Then the influence of extract of Radix Angelicae Dahuricae on the transport of puerarin was studied. Drug concentration was measured by HPLC and the apparent permeability coefficients (Papp) and apparent permeability ratio (PDR) were calculated. RESULTS AND CONCLUSIONS The results showed that the transport (Papp) of puerarin in Caco-2 cell monolayer model had time and concentration dependence, and the transport showed saturation characteristics with the time and concentration of puerarin to a certain degree. The Papp of puerarin transported on Caco-2 cell monolayer model was significantly changed when the specified inhibitors of P-gp were added to the model and the PDR decreased from 1.74 to 0.43. The absorption of puerarin was improved when combined with Radix Angelicae Dahuricae. The intestinal absorption of puerarin is by passive diffusion as the dominating process and active transportation was mediated by P-gp and MRP transporter in Caco-2 cell monolayer model, and Radix Angelicae Dahuricae could enhance the intestinal absorption of puerarin.

The absorption characterization effects and mechanism of Radix Angelicae dahuricae extracts on baicalin in Radix Scutellariae using in vivo and in vitro absorption models.

ETHNOPHARMACOLOGICAL RELEVANCE Angelicae Dahurica(Hoffm.)Benth.&Hook.f.ex Franch.&Sav combined with Scutellaria baicalensis Georgi. has been widely used as herb-pairs in traditional Chinese medicine (TCM) to treat migraine headache and cataract, but the underlying compatibility mechanism of the two herbs remains unknown. AIM OF STUDY In the present work, we investigated the additive or synergistic effects of absorption behavior of Radix Angelicae dahuricae extracts on baicalin, and the absorption-enhancing mechanism of Radix Angelicae dahuricae extracts on baicalin. MATERIALS AND METHODS Total coumarins (Cou) and volatile oil (VO), as the two main components of Radix Angelicae dahuricae, were extracted by supercritical fluid extraction (SFE) further treated with liquid-liquid separation method. The absorption behavior was investigated by applying the everted gut sac technique and in situ single-pass intestinal perfusion method. RESULTS AND CONCLUSIONS The results showed that both the Cou and the VO could improve the intestinal absorption of baicalin in vivo, and had synergistic action the enhanced absorption of baicalin. Since verapamil did not affect the P(app) and K(a) of baicalin significantly, we concluded that the absorption of Baicalin could not be an active transportation in dependent of P-glycoprotein-Mediated efflux systems. Based on intestinal absorption of drug studying was one of the efficacious methods to clarify the compatibility of principles of herb-pairs. The everted gut sac technique and in situ single-pass intestinal perfusion technique model were the effective methods to study the absorption of drug, the application of the animal model to investigating the absorption of herb-drug interactions or other relevant research purposes is envisioned.

Elucidation of the transport mechanism of baicalin and the influence of a Radix Angelicae Dahuricae extract on the absorption of baicalin in a Caco-2 cell monolayer model

ETHNOPHARMACOLOGICAL RELEVANCE Angelicae Dahurica (Hoffm.) Benth. & Hook. f. ex Franch. & Sav combined with Radix Scutellariae baicalensis Georgi has been widely used in traditional Chinese medicine (TCM) as an antipyretic analgesic and anti-inflammatory drug. Modern pharmacological studies have demonstrated that the compatible application of these two drugs is an effective treatment for hepatitis. A previous study indicated that a Radix Angelicae Dahuricae extract enhanced the intestinal absorption of the baicalin found in Radix Scutellariae; however, the underlying compatibility mechanism of these two herbs remains unknown. In this study, we further examined the effect of a Radix Angelicae Dahuricae extract on the absorption and transport properties of baicalin in a Caco-2 cell model to determine the compatibility mechanism of these two herbs. AIM OF THE STUDY The aim of this work was to study the transport properties of baicalin in Radix Scutellariae across cell membranes and the effects of a Radix Angelicae Dahuricae extract on baicalin absorption using the well-characterized, human-based intestinal Caco-2 cell model. MATERIALS AND METHODS We assessed the absorption, bidirectional transport and toxicity of baicalin using a range of parameters, including drug concentration, pH, a P-glycoprotein (P-gp) inhibitor (Verapamil), an MRP inhibitor (MK-571) and EDTA-Na2 (tight junction modulator). Next, we studied the influence of a Radix Angelicae Dahuricae extract on the transport of baicalin under the same conditions. Drug concentration was measured by HPLC, and the apparent permeability coefficient (Papp) and apparent permeability ratio (PDR) were subsequently calculated. RESULTS The results showed that baicalin is non-toxic within a concentration range of 800 µg/mL to 4800 µg/mL. The transport of baicalin showed time and concentration dependence. The absorption of baicalin was optimal at pH 7.4 in 37 °C; however, the absorption decreased at 4 °C. The Papp of baicalin transport through the Caco-2 cell monolayer model was altered when specific inhibitors of P-gp or MRP were added to the cells. However, there was no significant difference in the PDR value. The Papp of baicalin improved when it was combined with the Radix Angelicae Dahuricae extract. The influence of EDTA-Na2 on the transport of baicalin showed that the permeability of baicalin significantly increased. The result further indicated that the mechanism of baicalin intestinal absorption in the Caco-2 cell monolayer involves passive transcellular diffusion. CONCLUSIONS Passive diffusion is the main mode of intestinal absorption of bacalin and it involved in the efflux of proteins. The enhanced intestinal absorption of baicalin by Radix Angelicae Dahuricae can be due to opening of the tight junctions between cells and inhibition of MRP efflux protein expression or function.

Transport Properties of Puerarin and Effect of Extract of Radix Angelicae dahuricae on Puerarin Intestinal Absorption Using In Situ and In Vitro Models

The root of Angelica dahurica (Radix Angelicae Dahuricae, RAD), which contains coumarins and volatile oil as its main classes of active components, is often given in conjunction with Pueraria root (Radix Puerariae, RP), which contains the phytoestrogen puerarin. The two herbs are considered to be compatible ‘herb‐pairs’ in traditional Chinese medicine. The present investigation investigates the absorption of puerarin from RP and the effect of the total coumarins and volatile oil from RAD on its absorption. The everted gut sac and single‐pass intestinal perfusion methods were used, respectively. The results showed that the absorption of puerarin in the jejunum was significantly increased in the presence of the coumarins and/or volatile oil. The absorption rate constant (Ka) of puerarin increased gradually until the concentration reached 160 µg · mL−1, after which its absorption became saturated and the apparent permeability (Papp) values significantly decreased. The results showed that the intestinal absorption mechanisms of puerarin involved active transportation processes and that puerarin is likely to be a substrate of P‐gp because verapamil significantly affected its Papp and Ka. The absorption of puerarin significantly increased (p < 0.01) when combined with RAD extracts, as shown by the increase in concentration of puerarin in blood from the hepatic portal vein, supporting the concept of RAD and RP as a compatible herb‐pair. Copyright

Mechanisms of improvement of intestinal transport of baicalin and puerarin by extracts of Radix Angelicae Dahuricae.

Radix Angelicae Dahuricae is the dried root of Angelicae Dahurica (Fisch.ex Hoffm.)Benth.et Hook.f. var.formosana (Boiss.) Shan et Yuan (Fam.Umbelliferae). The total coumarins (Cou) and volatile oil (VO) were main active components that drived from Radix Angelicae Dahuricae. Our previous studies have shown that Cou and VO could increase intestinal absorption for transmucosal drug delivery with unknown mechanism. The aim of this study was to investigate the molecular mechanism of Radix Angelicae Dahuricae for improving drug intestinal transport. Caco‐2 cell model was used to study the effect of Radix Angelicae Dahurica on transepithelial electrical resistance. Western blot was used to study its effect on the expression of the actin and ZO‐1, tight junction proteins. The effect of Radix Angelicae Dahurica on the expression of P‐gp protein was investigated using flow cytometry. VO (0.036–2.88 μL/mL) and Cou (0.027–0.54 mg/mL) caused a reversible, time‐ and dose‐dependent decrease in transepithelial electrical resistance. VO and/or Cou could inhibit the expression of the tight junction protein, ZO‐1 and actin. VO and/or Cou also could inhibit the expression of P‐gp. These data suggested that Radix Angelicae Dahurica increased cell permeability by affecting the expression of actin, ZO‐1 or P‐gp, opening the tight junction or inhibiting the efflux induced by P‐gp. Copyright

Improvement of Transmembrane Transport Mechanism Study of Imperatorin on P-Glycoprotein-Mediated Drug Transport

P-glycoprotein (P-gp) affects the transport of many drugs; including puerarin and vincristine. Our previous study demonstrated that imperatorin increased the intestinal absorption of puerarin and vincristine by inhibiting P-gp-mediated drug efflux. However; the underlying mechanism was not known. The present study investigated the mechanism by which imperatorin promotes P-gp-mediated drug transport. We used molecular docking to predict the binding force between imperatorin and P-gp and the effect of imperatorin on P-gp activity. P-gp efflux activity and P-gp ATPase activity were measured using a rhodamine 123 (Rh-123) accumulation assay and a Pgp-Glo™ assay; respectively. The fluorescent probe 1,6-diphenyl-1,3,5-hexatriene (DPH) was used to assess cellular membrane fluidity in MDCK-MDR1 cells. Western blotting was used to analyze the effect of imperatorin on P-gp expression; and P-gp mRNA levels were assessed by qRT-PCR. Molecular docking results demonstrated that the binding force between imperatorin and P-gp was much weaker than the force between P-gp and verapamil (a P-gp substrate). Imperatorin activated P-gp ATPase activity; which had a role in the inhibition of P-gp activity. Imperatorin promoted Rh-123 accumulation in MDCK-MDR1 cells and decreased cellular membrane fluidity. Western blotting demonstrated that imperatorin inhibited P-gp expression; and qRT-PCR revealed that imperatorin down-regulated P-gp (MDR1) gene expression. Imperatorin decreased P-gp-mediated drug efflux by inhibiting P-gp activity and the expression of P-gp mRNA and protein. Our results suggest that imperatorin could down-regulate P-gp expression to overcome multidrug resistance in tumors.

Quantitative Evaluation of the Mechanism Underlying the Biotransportation of the Active Ingredients in Puerariae lobatae Radix and Chuanxiong rhizoma

The objective of this study was to establish a quantitative method to evaluate the biotransportation of a drug across the cell membrane. Through the application of the law of mass conservation, the drug transportation rate was calculated based on Ficks law of passive diffusion and the Michaelis–Menten equation. The overall membrane‐transportation rate was the sum of the passive diffusion rate and the carrier‐mediated diffusion rate, which were calculated as the transportation mass divided by the respective rate. The active ingredients of Puerariae lobatae Radix and Chuanxiong rhizoma, namely, puerarin and ferulic acid, respectively, were used as two model drugs. The transportation rates of puerarin and ferulic acid were obtained by fitting a model that includes both Ficks law of diffusion and the Michaelis–Menten equation. Compared with the overall transportation, the carrier‐mediated transport and passive diffusion of 1.59 mmol/L puerarin were −35.07% and 64.93%, respectively, whereas the respective transportation modes of 0.1 mmol/L ferulic acid were −35.40% and 64.60%, respectively. Verapamil and MK‐571 increased the overall transport rate and ratio, and MK‐571 treatment changed the carrier‐mediated transport from negative to positive. However, the transport rate and ratio of ferulic acid did not change significantly. The cell transportation mechanisms of puerarin and ferulic acid primarily involve simple passive diffusion and carrier‐mediated transportation. Moreover, P‐glycoprotein and multidrug resistance‐associated protein efflux proteins, and other transportation proteins were found to be involved in the transportation of puerarin. Copyright

Reversal Effect of Oxypeucedanin on P-glycoprotein-mediated Drug Transport

P-glycoprotein affects the transport of numerous drugs including chemotherapeutic drugs vincristine sulfate (VCR) and docetaxel (DTX), and is one of the main causes for multidrug resistance. Our previous studies have shown that oxypeucedanin (OPD) can enhance the intestinal transit of puerarin and VCR. However, the underlying mechanism is unclear. This study investigated the potential mechanism by which OPD improves P-gp-mediated drug transport. Molecular docking was performed to predict the binding force between OPD and P-gp and the contribution of OPD on P-gp activity. We observed the effect of OPD on the transport of VCR in MDCK-MDR1 cell monolayer and also measured the plasma pharmacokinetic parameters of DTX in the presence and absence of OPD by LC-MS/MS. Moreover, we further investigated the reversal mechanism of OPD on P-gp-mediated drug transport by determining the intracellular accumulation of Rhodamine-123 (Rh123) and P-gp ATPase activity as well as protein expression and mRNA level of P-gp. Our molecular docking results revealed that the binding force between OPD and P-gp was much lower than that between P-gp and verapamil (a P-gp substrate). The transport study in vitro indicated that OPD increased the flux of VCR across MDCK-MDR1 cell monolayer. The in vivo pharmacokinetic parameters data showed OPD increased the absorption of DTX. OPD activated P-gp ATPase activity and enhanced intracellular accumulation of Rh123 in MDCK-MDR1 cells. Western blotting and qRT-PCR outcomes indicated that OPD suppressed P-gp protein expression as well as downregulated P-gp mRNA level. Thus, OPD reverse P-gp-mediated drug transport via inhibition of P-gp activity and P-gp protein expression as well as downregulation of P-gp mRNA level. Our results suggest that OPD could reverse P-gp-mediated drug resistance in tumor cells.