Chemosensitizing effect and mechanism of imperatorin on the anti-tumor activity of doxorubicin in tumor cells and transplantation tumor model.

Multidrug resistance of tumors has been a severe obstacle to the success of cancer chemotherapy. The study wants to investigate the reversal effects of imperatorin (IMP) on doxorubicin (DOX) resistance in K562/DOX leukemia cells, A2780/Taxol cells and in NOD/SCID mice, to explore the possible molecular mechanisms. K562/DOX and A2780/Taxol cells were treated with various concentrations of DOX and Taol with or without different concentrations of IMP, respectively. K562/DOX xenograft model was used to assess anti-tumor effect of IMP combined with DOX. MTT assay, Rhodamine 123 efflux assay, RT-PCR, and Western blot analysis were determined in vivo and in vitro. Results showed that IMP significantly enhanced the cytotoxicity of DOX and Taxol toward corresponding resistance cells. In vivo results illustrated both the tumor volume and tumor weight were significantly decreased after 2-week treatment with IMP combined with DOX compared to the DOX alone group. Western blotting and RT-PCR analyses indicated that IMP downregulated the expression of P-gp in K562/DOX xenograft tumors in NOD/SCID mice. We also evaluated glycolysis and glutamine metabolism in K562/DOX cells by measuring glucose consumption and lactate production. The results revealed that IMP could significantly reduce the glucose consumption and lactate production of K562/DOX cells. Furthermore, IMP could also remarkably repress the glutamine consumption, α-KG and ATP production of K562/DOX cells. Thus, IMP may sensitize K562/DOX cells to DOX and enhance the anti-tumor effect of DOX in K562/DOX xenograft tumors in NOD/SCID mice. IMP may be an adjuvant therapy to mitigate the multidrug resistance in leukemia chemotherapy.

[Co-amorphous technology to improve dissolution and physical stability of silybin].

The present study explored the effect of co-amorphous technology in improving the dissolution rate and stability of silybin based on the puerarin-silybin co-amorphous system prepared by the spray-drying method. Solid-state characterization was carried out by powder X-ray diffraction(PXRD), polarizing microscopy(PLM), Fourier transform infrared spectroscopy(FT-IR), differential scanning calorimetry(DSC), etc. Saturated powder dissolution, intrinsic dissolution rate, moisture absorption, and stability were further investigated. The results showed that puerarin and silybin formed a co-amorphous system at a single glass transition temperature which was higher than that of any crude drug. The intrinsic dissolution rate and supersaturated powder dissolution of silybin in the co-amorphous system were higher than those of the crude drug and amorphous system. The co-amorphous system kept stable for as long as three months under the condition of 40 ℃, 75% relative humidity, which was longer than that of the single amorphous silybin. Therefore, the co-amorphous technology could significantly improve the dissolution and stability of silybin.

Nrf2 expands the intracellular pool of the chaperone AHSP in a cellular model of ß-thalassemia.

In ß-thalassemia, free α-globin chains are unstable and tend to aggregate or degrade, releasing toxic heme, porphyrins and iron, which produce reactive oxygen species (ROS). α-Hemoglobin-stabilizing protein (AHSP) is a potential modifier of ß-thalassemia due to its ability to escort free α-globin and inhibit the cellular production of ROS. The influence of AHSP on the redox equilibrium raises the question of whether AHSP expression is regulated by components of ROS signaling pathways and/or canonical redox proteins. Here, we report that AHSP expression in K562 cells could be stimulated by NFE2-related factor 2 (Nrf2) and its agonist tert-butylhydroquinone (tBHQ). This tBHQ-induced increase in AHSP expression was also observed in Ter119+ mouse erythroblasts at each individual stage during terminal erythroid differentiation. We further report that the AHSP level was elevated in α-globin-overexpressing K562 cells and staged erythroblasts from ßIVS-2-654 thalassemic mice. tBHQ treatment partially alleviated, whereas Nrf2 or AHSP knockdown exacerbated, α-globin precipitation and ROS production in fetal liver-derived thalassemic erythroid cells. MafG and Nrf2 occupancy at the MARE-1 site downstream of the AHSP transcription start site was detected in K562 cells. Finally, we show that MafG facilitated the activation of the AHSP gene in K562 cells by Nrf2. Our results demonstrate Nrf2-mediated feedback regulation of AHSP in response to excess α-globin, as occurs in ß-thalassemia.

Improvement of the bioavailability of curcumin by a supersaturatable self nanoemulsifying drug delivery system with incorporation of a hydrophilic polymer: in vitro and in vivo characterisation.

OBJECTIVES: The current study was focused on preparing curcumin (CUR) supersaturated self-nano-emulsion (PI-CUR-SNEDDS) using hydrophilic polymer and to study the influence of polymer precipitation inhibitor on the physicochemical and biopharmaceutical properties of the PI-CUR-SNEDDS. METHODS: PI-CUR-SNEDDS were prepared using hydrophilic polymer in order to maintain the supersaturation of CUR in nano-emulsion solution, artificial gastrointestinal fluid (AGF), and the precipitates formed, and characterised by in vitro dispersion tests, in vitro intestinal absorption and in vivo pharmacokinetic and compared with CUR-SNEDDS. KEY FINDINGS: PI-CUR-SNEDDS prepared with 2% hydroxypropyl methylcellulose 55-60 (HPMC55-60) as precipitation inhibitor (PI) significantly improved the viscosity, physical stability and CUR's equilibrium solubility of nanoemulsion. HPMC55-60 and CUR interact in AGF through intermolecular interactions, form hydrogen bonds, and produce amorphous precipitates. Compared with CUR-SNEDDS, the proportion of CUR in the hydrophilic phase increased by about 3-fold, and apparent permeability coefficient (Papp) in duodenum, jejunum, ileum, and colon increased by 2.30, 3.65, 1.54 and 2.08-fold, respectively, and the area under the plasma concentration-time curve0-12h of PI-CUR-SNEDDS also increased by 3.50-fold. CONCLUSIONS: Our results suggested that HPMC55-60 maintained the CUR supersaturation state by forming hydrogen bonds with CUR, increasing the solution's viscosity and drug solubilisation, thus improving the absorption and bioavailability of CUR.

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.

[Key physical parameters of hawthorn leaf granules by stepwise regression analysis method].

The purpose of this study was to investigate the effect of key physical properties of hawthorn leaf granule on its dissolution behavior. Hawthorn leaves extract was utilized as a model drug. The extract was mixed with microcrystalline cellulose or starch with the same ratio by using different methods. Appropriate amount of lubricant and disintegrating agent was added into part of the mixed powder, and then the granules were prepared by using extrusion granulation and high shear granulation. The granules dissolution behavior was evaluated by using equilibrium dissolution quantity and dissolution rate constant of the hypericin as the indicators. Then the effect of physical properties on dissolution behavior was analyzed through the stepwise regression analysis method. The equilibrium dissolution quantity of hypericin and adsorption heat constant in hawthorn leaves were positively correlated with the monolayer adsorption capacity and negatively correlated with the moisture absorption rate constant. The dissolution rate constants were decreased with the increase of Hausner rate, monolayer adsorption capacity and adsorption heat constant, and were increased with the increase of Carr index and specific surface area. Adsorption heat constant, monolayer adsorption capacity, moisture absorption rate constant, Carr index and specific surface area were the key physical properties of hawthorn leaf granule to affect its dissolution behavior.

[Correlation between four properties of traditional Chinese medicine and function of reversing multidrug resistance of tumor cells].

To study the correlation of four properties of traditional Chinese medicine and the function of reversing multidrug resistance (MDR) of tumor cells, with 580 herbs in Chinese Pharmacopoeia 2015 version as the research objects. CNKI, CBA, Wanfang, VIP, and PubMed were searched to screen the documents related to the reversal of MDR for collection, summarizing and analysis. The results of the research showed that a total of 114 species Chinese herbs had been reported to be associated with reversal of MDR in tumor cells. Among 15 Chinese herbs with heat nature, 7 herbs had the function of reversing MDR in tumor cells, accounting for 46.7%. Among the 48 herbs with cool nature, 12 herbs had the function of reversing MDR, accounting for 25%. Among the 211 herbs with cold nature, 46 herbs had the function of reversing MDR, accounting for 21.8%. Among the 179 herbs with warm nature, 34 herbs had the function of reversing MDR, accounting for 19%. Among the 127 herbs with neutral nature, 15 herbs had the function of reversing MDR, accounting for 11.8%. Through the analysis on the relationship between four properties of 114 kinds of traditional Chinese medicines and reversing multidrug resistance of tumor cells, this paper speculated that there was a certain correlation between four properties of traditional Chinese medicine and the function of reversing multidrug resistance of tumor cells.

[Effect investigation of coumarin constituents in Angelica dahurica on pharmacokinetics of docetaxel by LC-MS].

The study was aimed to establish a liquid chromatography-tandem mass spectrometric method for the determination of the docetaxel concentration in rat plasma, and study the effect of coumarin constituents (imperatorin, isoimperatorin and oxypeucedanin) in Angelica dahurica on pharmacokinetics of docetaxel.Plasma was precipitated with acetonitrile and determined by LC-MS method with Paclitaxel as an internal standard. The specificity, linearity, range, accuracy, precision and stability of the method were suitable for the determination of docetaxel in plasma.Six sprague-dawley rats in each group received intragastric administration of docetaxel (50 mg•kg⁻¹), oxypeucedanin (8 mg•kg⁻¹) combined with docetaxel (50 mg•kg⁻¹), imperatorin (15 mg•kg⁻¹) combined with docetaxel (50 mg•kg⁻¹), and isoimperatorin(15 mg•kg⁻¹) combined with docetaxel (50 mg•kg⁻¹).Their drug plasma concentration was determined by LC-MS with Paclitaxel as an internal standard to draw plasma concentration-time curve, and the phamacokinetic parameters were calculated by DAS 2.0. The results showed that the phamacokinetic parameters of docetaxel all had notable changes when combined with imperatorin, isoimperatorin, and oxypeucedanin, respectively. The phamacokinetic parameters AUC and Cmax were significantly increased, indicating that coumarin constituents in Angelica dahurica could promote the oral bioavailability of docetaxel, and their effects were in the following order: oxypeucedanin> isoimperatorin> imperatorin.

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.

[Improvement of powder flowability and hygroscopicity of traditional Chinese medicine extract by surface coating modification technology].

To study the improvement of powder flowability and hygroscopicity of traditional Chinese medicine extract by surface coating modification technology. The 1% hydrophobic silica nanoparticles were used as surface modifier, and andrographis extract powder was taken as a model drug. Three different techniques were used for coating model drugs, with angle of repose, compressibility, flat angle and cohesion as the comprehensive evaluation indexes for the powder flowability. The powder particle size and the size distribution were measured by Mastersizer 2000. FEI scanning electron microscope was used to observe the surface morphology and structure of the powder. The percentage of Si element on the powder surface was measured by energy dispersive spectrometer. The hygroscopicity of powder was determined by Chinese pharmacopoeia method. All of the three techniques can improve the flowability of powder extract. In particular, hygroscopicity of extract powder can also be improved by dispersion and then high-speed mixing, which can produce a higher percentage of Si element on the powder surface. The improvement principle may be correlated with a modifier adhered to the powder surface.

[Changes of specific chromatograms and contents of five components in Yinqiao powder decoctions during decocting process].

To establish a method for the determination of chemical specific chromatograms and five components in Yinqiao powder decoction, and provide basis for elucidating the scientific connotation of ″taking in when the fragrance volatilized fiercely″. Yinqiao powder decoctions with different decocting times were prepared to study the changes of chemical components during decocting process. Specific chromatograms and contents of chlorogenic acid, phillyrin, arctiin, liquiritin and glycyrrhizin were determined by high performance liquid chromatography. According to the results, the similarities of Yinqiao powder decoctions with different decocting times were high, which indicated that their chemical compositions were similar. The dissolutions of the five components in Yinqiao powder reached more than 39.7% of 2 hour maximum dissolution amounts (MDA) after 20 minutes of soaking, more than 69.5% of MDA when boiling, more than 79.1% of MDA at the 5th minute after boiling, and more than 85.7% of MDA at the 10th minute after boiling. The concentrations of five components were not increasing obviously after 15 minutes of boiling (RSD<4.3%). The fragrance volatilized fiercely at about the 5th minute after boiling, which indicated that the contents of volatile components in Yinqiao powder decoctions were high, but it became weak after boiling for 15 minutes, which indicated that the contents of volatile components in Yinqiao powder decoctions were low. The results showed that the contents of five components in Yinqiao powder decoctions were heavily influenced by the decocting time. When boiling for about 5 minutes, the fragrance volatilized fiercely, both the contents of volatile components and non-volatile components were high. It is suggested that the traditional decocting method has a certain scientific basis.

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 Fick's 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 Fick's 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 © 2015 John Wiley & Sons, Ltd.

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.

A new flavonol C-glycoside and a rare bioactive lignanamide from Piper wallichii Miq. Hand.-Mazz.

This study was conducted to investigate the chemical constituents of Piper wallichii (Miq.) Hand.-Mazz. and evaluate their biological activity. Compounds were isolated by various column chromatographic methods, and their structures were elucidated on the basis of physical characteristics and spectral data. The 1, 1-diphenyl-2-picrylhydrazyl (DPPH)-scavenging activity and acetylcholinesterase (AChE)-inhibitory activity of the compounds were evaluated. Five compounds were obtained and identified as 8-C-ß-D-glucopyranosylkaempferol-3-O-ß-D-glucopyranoside (1), 1, 2-dihydro-6,8-dimethoxy-7-hydroxy-1-(3, 5-dimethoxy-4-hydroxyphenyl)-N(1), N(2)-bis-[2-(4-hydroxyphenyl)ethyl]-2, 3-naphthalene dicarboxamide (2), goniothalactam (3), aristololactam A IIIa (4) and piperlonguminine (5). Compound 1 was a new flavonol C-glycoside, 2 was a rare lignanamide, which was isolated from the family Piperaceae for the first time, and compound 3 was isolated from this plant for the first time. Among them, 2 showed potent DPPH-scavenging activity, with IC50 of 31.38 ± 0.97 µmol·L(-1); Compounds 2, 3, and 4 showed AChE inhibitory activity at 100 µmol·L(-1), with inhibition rates of 28.57% ± 1.47%, 18.48% ± 2.41% and 17.4% ± 3.03%, respectively.

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 (K(a)) of puerarin increased gradually until the concentration reached 160 µg · mL(-1), after which its absorption became saturated and the apparent permeability (P(app)) 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 P(app) and K(a). 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.

[Determination of dissolution of liuwei dihuang concentrated pills based on multi-index components].

With the content of gallic acid, loganin, paeoniflorin and paeonol as the indexes, to screen out dissolution determination conditions, establish the dissolution determination method for multi-index components in Liuwei Dihuang concentrated pills, calculate and map the accumulative dissolution curve, and then compare the dissolution of products from different pharmaceutical factories through the similarity factor (f2). According to the results, the optimum dissolution determination conditions were the paddle method, with 250 mL 0.1 mol x L(-1) hydrochloric acid as the dissolution medium, and a rotation rate of 100 r x min(-1). The similarity factor values (f2) of the dissolution curves of the four main components of Liuwei Dihuang concentrated pills from different pharmaceutical factories were mostly less than 50. This demonstrated a significant difference in the dissolution of Liuwei Dihuang concentrated pills from different pharmaceutical factories, and provided scientific basis for improving the equality evaluation of Liuwei Dihuang concentrated pills.

[Correlations between micromeritic properties of mixing powders of danshen extract and formability of their pellets].

It was difficult to prepare traditional Chinese medicine pellets due to the adverse characteristics of the herbal extract. In this study, Danshen extract (DS) powder mixed with different proportions of microcrystalline cellulose (MCC), lactose and starch were made into pellets by extrusion-spheronization. Particle size, span, bulk density, tapping density, compressibility, Hausner ratio and angle of repose were used to evaluate the micromeritic properties of mixing powders. Feret diameter, aspect ratio, yield, density and friability were used to evaluate the properties of the pellets. The correlations between micromeritic properties of raw material powders and the formability of their pellets were analyzed by cluster analysis, principal component analysis and partial least squares regression analysis. As a result, the particle size of the powders was negatively correlated with the size, density, yield, and was positively correlated with the friability of their pellets. The span, density, compressibility and angle of repose of the powders were positively correlated with the size, density, yield, and were negatively correlated with the friability of their pellets. So there were certain correlations between the micromeritic properties of raw material powders and the properties of their pellets prepared by extrusion-spheronization. This research provided a foundation for the technology and method of traditional Chinese medicine extract pellets.

[Study on key physical properties of granulated products of Andrographis mixed powder by high-speed mixing wet method].

The impact of key physical properties on granulated products by the high-speed mixing wet method was studied. Andrographis extracts were utilized as the model drug. Four processing methods were adopted to prepare mixed powder of microcrystalline cellulose (MCC) and starch with the mass ratio 1:0.5, 1:1 and 1:2 by the high-speed mixing wet method. The properties of the prepared granules were evaluated with such indexes as granule yield, the ratio of lumps and fine powder, granule-AOR and granule-HR. The impact of key physical properties on granulated products was analyzed through stepwise regression analysis. The results showed that angle of repose, moisture content, pore volume, density and contact angle with water were key physical properties of the powder. The key physical properties of Chinese medical extracts powder are the important factor impacting granulated products made by the high-speed mixing wet method. In this study, the impact of key physical properties on granulated products of Chinese medical extracts was analyzed from the physical angle.

[Study on transport mechanism of baicalin in Scutellariae radix extracts and effect of Angelica dahurica extracts on transport of baicalin by Caco-2 cell monolayer model].

OBJECTIVE: To study the transport mechanism of baicalin of Scutellariae Radix extracts and the effect of Angelica dahurica extracts on the intestinal absorption of baicalin by using Caco-2 cell monolayer model, in order to analyze the effect mechanism of Angelica dahurica extracts on the intestinal absorption of baicalin. METHOD: The Caco-2 cell monolayer model was established with human colonic adenocarcinoma cells, and used to study the effect of pH, time, drug concentration and temperature on the transport of baicalin in Scutellariae Radix extracts, the effect of P-gp and MRP protein-dedicated inhibitors on the bidirectional transport of baicalin in Caco-2 cell model, and the effect of angelica root extracts on baicalin absorption and transport. RESULT: Baicalin was absorbed well at 37 degrees C and under pH 7.4 condition and concentration dependent. Its proteins became inactive at 4 degrees C, with a low transport. The bi-drectional transfer PDR was 0. 54. After P-gp inhibitor verapamil and MRP inhibitor probenecid were added, the value of PappBL-AP of baicalin decreased, but without any difference in PDR. The transport of baicalin was improved by 2.34, 3.31 and 3.13 times, after A. dahurica extract coumarin, volatile oil, and mixture of coumarin and volatile oil. CONCLUSION: The transport mechanism of baicalin is mainly passive transfer and supplemented with efflux proteins involved. A. dahurica extracts can enhance the absorption of baicalin, which may be related to the passive transfer merchanism of baicalin. A. dahurica extracts' effect in opening the close junction among cells may be related to its expression or function in inhibiting efflux proteins.

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.