Electroacupuncture stimulation enhances the permeability of the blood-brain barrier: A systematic review and meta-analysis of preclinical evidence and possible mechanisms.

An important cellular barrier to maintain the stability of the brain's internal and external environment is the blood-brain barrier (BBB). It also prevents harmful substances from entering brain tissue through blood circulation while providing protection for the central nervous system. It should be noted, however, that the intact BBB can be a barrier to the transport of most drugs into the brain via the conventional route of administration, which can prevent them from reaching effective concentrations for the treatment of disorders affecting the central nervous system. Electroacupuncture stimulation has been shown to be effective at opening the BBB in a series of experimental studies. This study systematically analyzes the possibility and mechanism by which electroacupuncture opens the BBB. In PubMed, Web of Science, VIP Database, Wanfang Database, and the Chinese National Knowledge Infrastructure, papers have been published for nearly 22 years aimed at opening the BBB and its associated structures. A comparison of EB content between electroacupuncture and control was selected as the primary outcome. There were also results on vascular endothelial growth factor (VEGF), nerve growth factor (NGF), P-Glycoprotein (P-gp), Matrix Metalloproteinase 9 (MMP-9), and glial fibrillary acidic protein (GFAP). We utilized Review Manager software analysis to analyze correlations between studies with a view to exploring the mechanisms of similarity. Evans Blue infiltration forest plot: pooled effect size of 2.04, 95% CI: 1.21 to 2.87, P < 0.01. These results indicate that electroacupuncture significantly increases EB penetration across the BBB. Most studies have reported that GFAP, MMP-9, and VEGF were upregulated after treatment. P-gp expression decreased as well. Electroacupuncture can open the BBB, and the sparse-dense wave is currently the most effective electroacupuncture frequency for opening the BBB. VEGF plays an important role in opening the BBB. It is also important to regulate the expression of MMP-9 and GFAP and inhibit the expression of P-gp.

Combination drug therapy by herbal nanomedicine prevent multidrug resistance protein 1: promote apoptosis in Lung Carcinoma.

Given the numerous adverse effects of lung cancer treatment, more research on non-toxic medications is urgently needed. Curcumin (CUR) and berberine (BBR) combat drug resistance by controlling the expression of multidrug resistant pump (MDR1). Fascinatingly, combining these medications increases the effectiveness of preventing lung cancer. Their low solubility and poor stability, however, restrict their therapeutic efficacy. Because of the improved bioavailability and increased encapsulation effectiveness of water-insoluble medicines, surfactant-based nanovesicles have recently received a great deal of attention. The current study sought to elucidate the Combination drug therapy by herbal nanomedicine prevent multidrug resistance protein 1: promote apoptosis in Lung Carcinoma. The impact of several tween (20, 60, and 80) types with varied hydrophobic tails on BBR/CUR-TNV was evaluated. Additionally, the MDR1 activity and apoptosis rate of the BBR/CUR-TNV combination therapy were assessed. The encapsulation effectiveness of TNV was affected by the type of tween. With the TNV made from tween 60, cholesterol, and PEG (47.5: 47.5:5), more encapsulation effectiveness was attained. By combining CUR with BBR, especially when given in TNV, apoptosis increased. Additionally, when CUR and BBR were administered in combination, they significantly reduced the risk of MDR1 development. The current work suggests that the delivery of berberine and curcumin as a combination medication therapy via tween-based nanovesicles may be a potential lung cancer treatment.

Lycorine and homolycorine derivatives for chemo-sensitizing resistant human ovarian adenocarcinoma cells.

BACKGROUND: Multidrug resistance is the major obstacle to cancer chemotherapy. Modulation of P-glycoprotein and drug combination approaches have been considered important strategies to overcome drug resistance. PURPOSE: Aiming at generating a small library of Amaryllidaceae-type alkaloids to overcome drug resistance, two major alkaloids, isolated from Pancratium maritimum, lycorine (1), and 2α-10bα-dihydroxy-9-O-demethylhomolycorine (2), were derivatized, giving rise to nineteen derivatives (3 - 21). METHODS: The main chemical transformation of lycorine resulted from the cleavage of ring E of the diacetylated lycorine derivative (3) to obtain compounds that have carbamate and amine functions (5 - 16), while acylation of compound 2 provided derivatives 17 - 21. Compounds 1 - 21 were evaluated for their effects on cytotoxicity, and drug resistance reversal, using resistant human ovarian carcinoma cells (HOC/ADR), overexpressing P-glycoprotein (P-gp/ABCB1), as model. RESULTS: Excluding lycorine (1) (IC50 values of 1.2- 2.5 µM), the compounds were not cytotoxic or showed moderate/weak cytotoxicity. Chemo-sensitization assays were performed by studying the in vitro interaction between the compounds and the anticancer drug doxorubicin. Most of the compounds have shown synergistic interactions with doxorubicin. Compounds 5, 6, 9 - 14, bearing both carbamate and aromatic amine moieties, were found to have the highest sensitization rate, reducing the dose of doxorubicin 5-35 times, highlighting their potential to reverse drug resistance in combination chemotherapy. Selected compounds (4 - 6, 9 - 14, and 21), able of re-sensitizing resistant cancer cells, were further evaluated as P-gp inhibitors. Compound 11, which has a para­methoxy-N-methylbenzylamine moiety, was the strongest inhibitor. In the ATPase assay, compounds 9-11 and 13 behaved as verapamil, suggesting competitive inhibition of P-gp. At the same time, none of these compounds affected P-gp expression at the mRNA or protein level. CONCLUSIONS: This study provided evidence of the potential of Amaryllidaceae alkaloids as lead candidates for the development of MDR reversal agents.

Enhancing lathyrane structural diversity and MDR activity by combinatorial modification of lathyrane nucleus and ester side chain: A case study of Euphorbia Factor L1 and Euphorbia Factor L3.

The chemical transformation of lathyrane nucleus through reduction and oxidation reactions using Euphorbia Factor L1 (EFL1) and Euphorbia Factor L1 (EFL3) as examples were investigated, along with a co-modification strategy of lathyrane nucleus and its side ester chain. A total of 38 lathyrane derivatives (5-42) including 34 new compounds were obtained, which greatly enriched the structural diversity of the lathyrane-type diterpenoids. Cytotoxicity against drug-sensitive and drug (adriamycin, ADM) resistant MCF-7 cells showed that 23 out of 38 transformed derivatives possessed obvious cytotoxic activity with IC50 values ranging from 7.0 to 41.1 µM and 3.2 to 45.5 µM, respectively, against both cells, compared to the noncytotoxic EFL1 and EFL3. The multidrug resistance (MDR) reversing activities of these lathyrane derivatives were further evaluated in MCF-7/ADM. Three transformed compounds (reversal fold, RF = 151.33, 62.94 and 47.3 for 27, 37 and 42) showed markedly higher activity than EFL1 (RF = 32.92) and EFL3 (RF = 39.68). Structure-activity relationship study revealed an essential role of C-6/17 and C-12/13 double bonds on lathyrane nucleus for exerting MDR reversal activity. Western blotting analysis showed that 42 could reduce the expression level of P-glycoprotein (P-gp) in MCF-7/ADM cells; however, the most active compound 27 with an unnatural 5/7/7/4 fused-ring diterpenoid skeleton, had no inhibitory effect on P-gp expression.

Elucidation the mechanism of the active ingredient imperatorin promoting drug absorption in cell model.

Imperatorin (IMP) is the main bioactive furanocoumarin of Angelicae dahuricae radix, which is a well-known traditional Chinese medicine. The purpose of this study was to elucidate the role of IMP in promoting absorption and the possible mechanism on the compatible drugs of Angelicae dahuricae radix. The influence of IMP on drugs' intestinal absorption was conducted by the Caco-2 cell model. The mechanism was studied by investigating the transcellular transport mode of IMP and its influence on P-glycoprotein (P-gp)-mediated efflux, protein expression of P-gp and tight junction, and cell membrane potential. The result showed IMP promoted the uptake of osthole, daidzein, ferulic acid, and puerarin and improved the transport of ferulic acid and puerarin in Caco-2 cells. The absorption-promoting mechanism of IMP might involve the reduction of the cell membrane potential, decrease of P-gp-mediated drug efflux and inhibition of the P-gp expression level in the cellular pathway, and the loosening of the tight junction protein by the downregulation of the expression levels of occludin and claudin-1 in the paracellular pathway. This study provides new insights into the understanding of the improved bioavailability of Angelicae dahuricae radix with its compatible drugs.

Mosloflavone from Fissistigma petelotii ameliorates oncogenic multidrug resistance by STAT3 signaling modulation and P-glycoprotein blockade.

BACKGROUND: Oncogenic multidrug resistance (MDR) is a tough question in cancer therapy. However, no effective medications targeting oncogenic MDR are currently available. Studies have demonstrated that mosloflavone exerts anti-inflammatory effects, yet, its potential to ameliorate MDR remains unclear. PURPOSE: This study aimed to access the capability and elucidate molecular mechanisms of mosloflavone as a MDR resensitizing candidate. METHODS: We investigated the ability of mosloflavone to reverse oncogenic MDR and investigated its underlying mechanisms through cytotoxicity assay, cell cycle assay, apoptosis assay, and zebrafish xenograft model. The modulatory interplay between mosloflavone and P-gp was investigated through analysis of calcein-AM uptake, substrate efflux, ATPase assays, and molecular docking simulation. RESULTS: Mosloflavone inhibited P-gp efflux function in an uncompetitive manner without altering ABCB1 gene expression. In addition, it stimulated P-gp ATPase activity by binding to an active site distinct from that of verapamil. Regarding MDR reversal potential, mosloflavone resensitized MDR cancer cells to chemotherapies by arresting cell cycle and triggering apoptosis, possibly by enhancing reactive oxygen species accumulation and reducing phospho-STAT3. Moreover, in the zebrafish xenograft model, mosloflavone significantly potentiated the antitumor effect of paclitaxel. CONCLUSION: Our findings underscore the potential of mosloflavone as a novel dual modulator of STAT3 and P-gp, indicating it is a promising candidate for overcoming MDR in cancer treatment.

Overcoming multi drug resistance mediated by ABC transporters by a novel acetogenin- annonacin from Annona muricata L.

ETHNOPHARMACOLOGICAL RELEVANCE: Multi-Drug Resistance (MDR), mediated by P-glycoprotein (P-gp) is one of the barriers to successful chemotherapy in colon cancer patients. Annona muricata L. (A.muricata), commonly known as soursop/Graviola, is a medicinal plant that has been traditionally used in treating diverse diseases including cancer. Phytochemicals of A.muricata (Annonaceous Acetogenins-AGEs) have been well-reported for their anti-cancer effects on various cancers. AIM OF THE STUDY: The study aimed to examine the effect of AGEs in reversing MDR in colorectal cancer cells. METHODS: Based on molecular docking and molecular dynamic simulation, the stability of annonacin upon P-gp was investigated. Further in vitro studies were carried in oxaliplatin-resistant human colon cancer cells (SW480R) to study the biological effect of annonacin, in reversing drug resistance in these cells. RESULTS: Molecular docking and simulation studies have indicated that annonacin stably interacted at the drug binding site of P-gp. In vitro analysis showed that annonacin was able to significantly reduce the expression of P-gp by 2.56 folds. It also induced apoptosis in the drug-resistant colon cancer cells. Moreover, the intracellular accumulation of P-gp substrate (calcein-AM) was observed to increase in resistant cells upon treatment with annonacin. CONCLUSION: Our findings suggest that annonacin could inhibit the efflux of chemotherapeutic drugs mediated by P-gp and thereby help in reversing MDR in colon cancer cells. Further in vivo studies are required to decipher the underlying mechanism of annonacin in treating MDR cancers.

Study on the reversal of epileptic drug resistance by tetramethylpyrazine in combination with carbamazepine through modulation of P-Glycoprotein expression in rat brain microvessel endothelial cell.

The purpose of this study was to detect the changes of P-Glycoprotein (P-GP) expression in rat brain microvessel endothelial cell line RBE4 after the action of Tetramethylpyrazine (TMP) on Carbamazepine (CBZ), so as to clarify the potential mechanism of TMP combined with CBZ against intractable epilepsy drug resistance. The RBE4 cell line was utilized for in vitro analysis. Cells were divided into control, CBZ, and CBZ-TMP group. The expression of P-GP was assessed using Western blot and reverse transcription polymerase chain reaction (RT-PCR). Intracellular concentration of CBZ was measured through high-performance liquid chromatography (HPLC). The differential expression of mRNA was evaluated by RNA sequencing. The intracellular concentration of CBZ in the CBZ-TMP group was significantly higher than that in other groups. The expression of P-GP in the CBZ group was significantly higher than that in the control group, while in the CBZ&TMP group, it was significantly lower than that in the other groups. Comparative analysis also revealed some differentially expressed genes. Compared with the CBZ group, FAM106A, SLC3A2, TENM2, etc. were upregulated most significantly in the CBZ&TMP group. ZBTB10, WDR7, STARD13, etc. were downregulated most significantly. Results suggest that TMP increases the intracellular concentration of CBZ, downregulates the expression of P-GP increased by CBZ, and modulates related cellular metabolism and signaling pathways, thus reversing the drug resistance mechanism of intractable epilepsy, providing a theoretical basis for the combination of traditional Chinese medicine and antiepileptic drugs.

Metformin alleviates adriamycin resistance of osteosarcoma by declining YY1 to inhibit MDR1 transcriptional activity.

Chemotherapy resistance hinders the successful treatment of osteosarcoma (OS) to some extent. Previous studies have confirmed that metformin (Met) enhances apoptosis induced by chemotherapeutic drugs, but the underlying mechanism remains unclear. To establish adriamycin (ADM)-resistant MG-63 (MG-63/ADM) cells, the dosage of ADM was progressively increased. The results of qRT-PCR and Western blotting demonstrated that the expression level of Yin Yang 1 (YY1) and multi-drug resistance-1 (MDR1) in MG-63/ADM cells were remarkably increased compared with those in MG-63 cells. Met dramatically enhanced ADM cytotoxicity and accelerated apoptosis of MG-63/ADM cells. Moreover, Met suppressed the expressions of YY1 and MDR1 in MG-63/ADM cells. YY1 promoted its transcriptional expression by directly binding to the MDR1 promoter. Furthermore, the effects of Met on ADM sensitivity in MG-63/ADM cells was reversed due to overexpression of YY1 or MDR1. Collectively, these findings suggested that Met inhibited YY1/MDR1 pathway to reverse ADM resistance in OS, providing a new insight into the mechanism of Met in ADM resistance of OS.

Mechanism of Quercetin as a Multidrug-resistant Reversing Compound in Oxaliplatin-resistant Gastric-cancer Cell Lines.

Context: Treatment failure due to multidrug resistance (MDR) is a crucial hurdle during chemotherapy. MDR is generally correlated with an upregulation of adenosine triphosphate (ATP)-binding cassette (ABC) transport proteins. Also, aberrant activation of the phosphoinositide 3-kinase (PI3K)/ protein kinase B (Akt) pathway can counteract chemotherapeutic induction. Identification of safe and functioning MDR-reversing compounds is necessary in gastric-cancer therapy. Objective: The study intended to examine the role of Quercetin (Qur) in the mediation of osmotic glycoprotein (P-gp) expression and activity as an ABC transporter in the PI3K/Akt/ P-gp cascade in the oxaliplatin (OxR)-resistant, gastric-cancer cell line KATOIII/OxR. Design: The research team performed a laboratory study. Setting: The study took place at Nantong Haimen People's Hospital. Outcome Measures: The research team: (1) determined the impact of OxR on cell viability after treatment with Qur using trypan blue and "3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide" (MTT) assays; (2) employed a rhodamine 123 (Rh123) assay to detect the activity of P-gp; (3) used quantitative reverse transcription polymerase chain reaction (RT-qPCR) to measure mRNA expression of P-gp; and (4) detected apoptosis using an enzyme-linked immunoassay (ELISA) cell-death assay. Results: Qur: (1) increased the cytotoxicity of OxR; (2) downregulated the expression level and activity of P-gp and reversed MDR through the enhancement of the cytotoxicity of intracellular OxR in KATOIII/OxR cells; and (3) enhanced the apoptosis rate in KATOIII/OxR cells. Conclusions: Qur induced a dramatic reduction in the survival rate of KATOIII/OxR cells and may reverse OxR resistance through a decrease in P-gp expression and activity. These data imply that exposure of KATOIII/OxR cells in the dose-dependent manner to Qur can circumvent MDR by improving the intracellular accumulation of OxR. Qur might provide a new treatment strategy and improve patients' survival after chemotherapy for gastric cancer.

Black ginger extract and its active compound, 5,7-dimethoxyflavone, increase intestinal drug absorption via efflux drug transporter inhibitions.

Black ginger is used as an herbal medicine for self-care and health promotion. Black ginger extract has been shown to alter the function of transporters in several cell types. This study demonstrates the interaction between the extract and 5,7-dimethoxyflavone (DMF) on drug efflux mediated by breast cancer resistance proteins (BCRP) and P-glycoprotein (P-gp) in Caco-2 cells and heterologous cell systems [Madin-Darby canine kidney type II (MDCKII) stably transfected with human BCRP (MDCKII/BCRP) or human P-gp (MDCKII/P-gp)]. The transepithelial flux of 3H-Digoxin and 3H-Estrone sulfate, prototypic substrates of P-gp, and BCRP, respectively, across Caco-2 cell monolayers, MDCKII/BCRP, and MDCKII/P-gp cells were determined. The results demonstrate that black ginger extract (10 µg/ml) significantly increases 3H-Digoxin and 3H-Estrone sulfate transport from the apical to basolateral side while decreasing transport from the basolateral to apical side of Caco-2 cells and MDCKII cell overexpression of BCRP or P-gp. The effect of the extract on 3H-Digoxin and 3H-Estrone sulfate transport was related to a decrease in efflux ratio. Likewise, DMF (5 µM) significantly increased 3H-Digoxin and 3H-Estrone sulfate absorption with a decreased efflux ratio compared to the control. Interestingly, the extract also significantly increased absorption of paclitaxel, an anti-cancer drug, which has poor oral absorption. Taken together, co-administration of drugs as substrates of BCRP and P-gp, with the black ginger extract containing DMF, might alter the pharmacokinetic profiles of the medicine.

In Vivo Reversal of P-Glycoprotein-Mediated Drug Resistance in a Breast Cancer Xenograft and in Leukemia Models Using a Novel, Potent, and Nontoxic Epicatechin EC31.

The modulation of P-glycoprotein (P-gp, ABCB1) can reverse multidrug resistance (MDR) and potentiate the efficacy of anticancer drugs. Tea polyphenols, such as epigallocatechin gallate (EGCG), have low P-gp-modulating activity, with an EC50 over 10 µM. In this study, we optimized a series of tea polyphenol derivatives and demonstrated that epicatechin EC31 was a potent and nontoxic P-gp inhibitor. Its EC50 for reversing paclitaxel, doxorubicin, and vincristine resistance in three P-gp-overexpressing cell lines ranged from 37 to 249 nM. Mechanistic studies revealed that EC31 restored intracellular drug accumulation by inhibiting P-gp-mediated drug efflux. It did not downregulate the plasma membrane P-gp level nor inhibit P-gp ATPase. It was not a transport substrate of P-gp. A pharmacokinetic study revealed that the intraperitoneal administration of 30 mg/kg of EC31 could achieve a plasma concentration above its in vitro EC50 (94 nM) for more than 18 h. It did not affect the pharmacokinetic profile of coadministered paclitaxel. In the xenograft model of the P-gp-overexpressing LCC6MDR cell line, EC31 reversed P-gp-mediated paclitaxel resistance and inhibited tumor growth by 27.4 to 36.1% (p < 0.001). Moreover, it also increased the intratumor paclitaxel level in the LCC6MDR xenograft by 6 fold (p < 0.001). In both murine leukemia P388ADR and human leukemia K562/P-gp mice models, the cotreatment of EC31 and doxorubicin significantly prolonged the survival of the mice (p < 0.001 and p < 0.01) as compared to the doxorubicin alone group, respectively. Our results suggested that EC31 was a promising candidate for further investigation on combination therapy for treating P-gp-overexpressing cancers.

Effect of P-Glycoprotein on the Blood-Brain Barrier Transport of the Major Active Constituents of Salvia miltiorrhiza Based on the MDCK-MDR1 Cell Model.

Salvia miltiorrhiza Bunge (S. miltiorrhiza) is a traditional Chinese medicine that has been widely used in the treatment of various central nervous system (CNS) diseases. However, the mechanism of active components of S. miltiorrhiza crossing the blood-brain barrier (BBB) stays unclear. The purpose of this study was to clarify the mechanism of four ingredients of S. miltiorrhiza, i.e., cryptotanshinone (CTS), dihydrotanshinone I (DTS I), tanshinone IIA (TS IIA), and protocatechuic acid (PCTA) crossing the BBB using the in vitro model. The bidirectional transport of detectable components was tested using the MDCK-MDR1 monolayers. High performance liquid chromatography coupled to triple-quadrupole mass spectrometry (HPLC-QQQ/MS) was used to detect the content changes of S. miltiorrhiza monomer components transported through the BBB. Papp of CTS, DTS I, and TS IIA in the absorption direction were lower than 1.0 × 10-6 cm/s, suggesting that these components were poorly absorbed, while PCTA was moderately absorbed through the BBB. The efflux ratio (ER) of CTS, DTS I, TS IIA, and PCTA were 1.65, 0.92, 4.27, and 1.48, respectively. After treatment with P-gp inhibitor tariquidar, the efflux ratio (ER) of CTS, DTS I, and TS IIA significantly decreased from 1.65 to 1.27, 0.92 to 0.36, and 4.27 to 0.86 (P < 0.05), respectively, while the efflux ratio of PCTA decreased without significance from 1.48 to 0.80. This indicated that the transport of CTS, DTS I, and TS IIA might be related to P-gp. TS IIA and CTS were verified as the substrates of P-gp among the four components since the ER of TS IIA and CTS is greater than 1.5. For PCTA and DTS I, their transport mechanism may be related to other transport proteins or passive transport. The results were confirmed by molecular docking in our current work. In this study, an in vitro BBB model was established and applied to the trans-BBB study of active components in S. miltiorrhiza for the first time, which may provide a basis for further research on the mechanisms of other TCMs in treating CNS diseases and is of great significance in promoting the rational and effective use of TCMs.

Electrochemical immunosensor based on AuNPs/ERGO@CNT nanocomposites by one-step electrochemical co-reduction for sensitive detection of P-glycoprotein in serum.

P-glycoprotein (P-gp), a transmembrane glycoprotein widely expressed on the surface of various cells, is highly associated with multidrug resistance (MDR) that heralds the malignant progress of disease after drug treatment. Notably, there have been reported that serum P-gp is a potential marker for assessing the progression of disease resistance. Currently, there are few methods for point-of-care serum P-gp detection. In this study, we proposed a gold nanoparticles/electrochemically reduced graphene oxide@carbon nanotube (AuNPs/ERGO@CNT) modified immunosensor based on a one-step electrochemical co-reduction method. The limit of detection (LOD) of our constructed electrochemical immunosensor for P-gp detection reached 0.13 ng/mL, and the detection results in serum were consistent with ELISA. The developed immunosensor is expected to provide a scientific basis for the clinical application of serum P-gp monitoring and integrated medicine.

Transporter-mediated Natural Product-Drug Interactions.

The increasing use of natural products in clinical practice has raised great concerns about the potential natural product-drug interactions (NDIs). Drug transporters mediate the transmembrane passage of a broad range of drugs, and thus are important determinants for drug pharmacokinetics and pharmacodynamics. Generally, transporters can be divided into ATP binding cassette (ABC) family and solute carrier (SLC) family. Numerous natural products have been identified as inhibitors, substrates, inducers, and/or activators of drug transporters. This review article aims to provide a comprehensive summary of the recent progress on the research of NDIs, focusing on the main drug transporters, such as P-glycoprotein (P-gp), breast cancer resistance protein (BCRP), organic anion transporter 1 and 3 (OAT1/OAT3), organic anion-transporting polypeptide 1B1 and 1B3 (OATP1B1/OATP1B3), organic cation transporter 2 (OCT2), multidrug and toxin extrusion protein 1 and 2-K (MATE1/MATE2-K). Additionally, the challenges and strategies of studying NDIs are also discussed.

Effect of Oregon grape root extracts on P-glycoprotein mediated transport in in vitro cell lines.

Purpose: This study aims to investigate the potential of Oregon grape root extracts to modulate the activity of P-glycoprotein. Methods: We performed 3H-CsA or 3H-digoxin transport experiments in the absence or presence of two sources of Oregon grape root extracts (E1 and E2), berberine or berbamine in Caco-2 and MDCKII-MDR1 cells. In addition, real time quantitative polymerase chain reaction (RT-PCR) was performed in Caco-2 and LS-180 cells to investigate the mechanism of modulating P-glycoprotein. Results: Our results showed that in Caco-2 cells, Oregon grape root extracts (E1 and E2) (0.1-1 mg/mL) inhibited the efflux of CsA and digoxin in a dose-dependent manner. However, 0.05 mg/mL E1 significantly increased the absorption of digoxin. Ten µM berberine and 30 µM berbamine significantly reduced the efflux of CsA, while no measurable effect of berberine was observed with digoxin. In the MDCKII-MDR1 cells, 10 µM berberine and 30 µM berbamine inhibited the efflux of CsA and digoxin. Lastly, in real time RT-PCR study, Oregon grape root extract (0.1 mg/mL) up-regulated mRNA levels of human MDR1 in Caco-2 and LS-180 cells at 24 h. Conclusion: Our study showed that Oregon grape root extracts modulated P-glycoprotein, thereby may affect the bioavailability of drugs that are substrates of P-glycoprotein.

Vinegar-baked Radix Bupleuri enhances the liver-targeting effect of rhein on liver injury rats by regulating transporters.

OBJECTIVE: This study aimed to explore whether the liver-targeting enhancing effect of vinegar-baked Radix Bupleuri (VBRB) on rhein was achieved by affecting transporters, metabolism enzymes as well as hepatocyte nuclear factor 1α/4α (HNF1α/HNF4α) in liver injury. METHODS: The effect of VBRB on the efficacy of rhein was performed with the LPS-induced acute liver injury rat model. Aspartate aminotransferase (AST), alanine transaminase (ALT) and superoxide dismutase (SOD) levels were determined and histopathological examination was taken. Drug concentrations in tissues were determined by high performance liquid chromatography (HPLC). The protein expressions of drug transporters, metabolic enzymes and hepatic nuclear factors were determined by Western blotting and ELISA assays. KEY FINDING: VBRB improved the liver protecting effect of rhein, which was consistent with its promoting effect on targeted enrichment of rhein in the liver. VBRB or in combination with rhein inhibited P-glycoprotein (Pgp) and multi-resistance related protein 2 (MRP2), while increased organic anion transporting polypeptide 2 (OATP2), which might be the reason why VBRB promoted liver-targeting effect of rhein. CONCLUSION: VBRB enhances the liver-protecting effect of rhein by down-regulating Pgp, MRP2, and up-regulating OATP2.

Mahanimbine isolated from Murraya koenigii inhibits P-glycoprotein involved in lung cancer chemoresistance.

P-glycoprotein (P-gp), a transmembrane glycoprotein, is mainly involved in lung cancer multidrug resistance. Several P-gp inhibitors have been developed to enhance the efficacy of chemotherapeutics and overcome drug resistance. However, most of them failed in the clinical stages due to undesirable side effects. Therefore, there is a requirement to develop P-gp inhibitors from natural sources. Dietary spice bioactives have been well-known for their anticancer activities. However, their role in modulating the P-gp activity has not been well investigated. Therefore, we have screened for the potential bioactives from various spice plants with P-gp modulatory activity using computational molecular docking analysis. The computational analysis revealed several key bioactives from curry leaves, specifically mahanimbine, exhibited a strong binding affinity with P-gp. Unfortunately, mahanimbine is available with few commercial sources at very high prices. Therefore, we prepared a curry leaves extract and isolated mahanimbine by a novel, yet simple, extraction method that requires less time and causes minimum environmental hazards. After purification, structure, and mass were confirmed for the isolated compound by IR spectrum and LC-MS/MS analysis, respectively. In the mechanistic study, hydrolysis of ATP and substrate efflux by P-gp are coupled. Hence, ATP binding at the ATPase-binding site is one of the fundamental steps for the P-gp efflux cycle. We found that mahanimbine demonstrated to stimulate P-gp ATPase activity. Concurrently, it enhanced the intracellular accumulation of P-gp substrates Rhodamine 123 and Hoechst stain, which indicates that mahanimbine modulates the function of P-gp. In addition, we have analyzed the complementary effect of mahanimbine with the chemotherapeutic drug gefitinib. We found that mahanimbine synergistically enhanced gefitinib efficiency by increasing its intracellular accumulation in lung cancer cells. Overall, mahanimbine has been shown to be a potent P-gp modulator. Therefore, mahanimbine can be further developed as a potential candidate to overcome chemoresistance in lung cancer.

Methoxylated flavones with potential therapeutic and photo-protective attributes: Theoretical investigation of substitution effect.

The molecular and electronic structure of parent flavone and 49 (poly)methoxylated flavones (P)MFs were studied theoretically. Selected group of flavonoids consists of compounds naturally occurring in citrus plants or synthetic derivatives of flavone. These compounds exhibit several bioactivities in vitro and in vivo and can protect plants from solar ultraviolet (UV) radiation. Substitution induced structural changes in (P)MFs were correlated with published experimental values of P-glycoprotein inhibition effect. We have demonstrated that the C5-C10 bond length of 1-benzopyran-4-one moiety represents a suitable structural descriptor for this bioactivity. Obtained linear equations for the compounds with substituted and non-substituted C3 position enable the prediction of the potential anti-cancer chemo-preventive effect of the rest of studied (P)MFs. Consequently, potentially more effective substances were suggested. Optical properties of (P)MFs and their relationship with the molecular structure was examined in detail for methanol environment, as well. The multiple linear regression model was applied to assess the correlation between experimental absorption and fluorescence wavelengths with the theoretically predicted ones. The UV photo-protective potential of studied derivatives was estimated from the calculated optical properties.

The Prevention and Reversal of a Phenytoin-Resistant Model by N-acetylcysteine Therapy Involves the Nrf2/P-Glycoprotein Pathway at the Blood-Brain Barrier.

The transporter hypothesis is one of the most popular hypotheses of drug-resistant epilepsy (DRE). P-glycoprotein (P-gp), a channel protein at the blood-brain barrier (BBB), plays an important role in the transport of some anti-seizure drugs from brain tissue into vessels, which reduces drug concentrations and diminishes the effects of drug treatment. We performed this study to test whether P-gp is overexpressed in DRE and identify ways to prevent and reverse DRE. In this study, we established a phenytoin (PHT)-resistant mouse model and revealed that P-gp was overexpressed at the BBB in PHT-resistant mice. The P-gp inhibitor nimodipine decreased the resistance of phenytoin. Antioxidative preventive treatment with N-acetylcysteine (NAC) prevented the mice from entering a PHT-resistant state, and NAC therapy tended to reverse PHT resistance into sensitivity. We were also able to induce PHT resistance by activating the Nrf2/P-gp pathway, which indicates that oxidative stress plays an important role in drug resistance. Taken together, these findings suggest that antioxidative therapy may be a promising strategy for overcoming DRE.