Potential synergic mechanism of Wutou-Gancao herb-pair by inhibiting efflux transporter P-glycoprotein

Investigation of the attenuation effect of licorice on the toxicity of rhubarb using a P-gp lipid raft bioaffinity chromatography

ETHNOPHARMACOLOGICAL RELEVANCE

As a classic clinical drug pair that was first recorded in Shanghan Lun, the combination of rhubarb and licorice has been known to reduce the toxic side effects of rhubarb, while enhancing its therapeutic efficacy. Despite its benefits, the exact mechanism through which licorice mitigates toxicity requires further investigation.

AIM OF THE STUDY

This research seeks to explore the effect of main active components of licorice on absorption and transport of rhein and emodin as well as provide new insights into the detoxification properties of licorice.

MATERIALS AND METHODS

A P-glycoprotein (P-gp) lipid raft bioaffinity chromatography was developed to screen the main active components of licorice and rhubarb. Afterward, molecular docking was applied to study the interactions of these components with breast cancer resistance protein (BCRP), multidrug resistance-associated protein 2 (MRP2), and P-gp efflux proteins. Further experiments were conducted to investigate the effects of these components on efflux transporters and their impact on absorption and transport of rhein and emodin.

RESULTS

The P-gp lipid raft bioaffinity chromatography could effectively screen the active components in rhubarb and licorice that interacted with P-gp. Molecular docking, Western blot and real time-polymerase chain reaction (RT-PCR) experiments showed that glycyrrhizin (GL), glycyrrhetinic acid (GA), and liquiritin (LI) interacted with P-gp, BCRP, and MRP2, thereby promoting their efflux and increasing their expression. Additionally, GA reduced Claudin-1 protein expression with further studies confirming that these components enhanced the efflux of rhein and emodin.

CONCLUSION

This study found that GL and GA derived from licorice could reduce the toxicity of rhein and emodin in Caco-2 cells, enhance P-gp efflux, and provide new insights into detoxification mechanisms of licorice.

Insights on neuropharmacological benefits and risks: Aconitum carmichaelii Debx

Aconitum carmichaelii Debx., a traditional herb known for its potent bioactivities, has been widely used in Traditional Chinese Medicine, particularly in the forms of Chuanwu and Fuzi. Despite the therapeutic benefits of this plant, concerns have been raised regarding its neuropharmacological actions and potential neurotoxicity. This paper provides an in-depth analysis of the neuropharmacological effects, neurotoxicological mechanisms, and toxicity biomarkers of Aconitum roots. The neuropharmacological properties are linked to alterations in neurotransmitter synthesis and ion transport modulation, while the neurotoxic effects are primarily attributed to oxidative stress responses and the induction of mitochondrial apoptosis pathways. Through metabolomic profiling, we have identified several metabolic pathways affected by Aconitum roots, with a significant impact on tryptophan metabolism, which in turn influences cardiovascular and nervous system functions, liver detoxification, and energy metabolism. Furthermore, we discuss the modulation of ion channel protein activity, which is evidenced by recent studies, suggesting a critical role in the neurotoxic effects of Aconitum. An early detection strategy for toxicity biomarkers using metabonomics is proposed, emphasizing its crucial role in enhancing the diagnosis and treatment of Aconitum poisoning. It is recommended that regular monitoring of individuals at risk of Aconitum toxicity, including habitual consumers of TCM and accidental ingestion of the plant, be conducted in order to prevent toxic outcomes. This review emphasizes the importance of understanding the dual nature of Aconitum as both a therapeutic agent and a potential neurotoxin, aiming to optimize its clinical use and ensure patient safety.

Aconitine in Synergistic, Additive and Antagonistic Approaches

Aconitine is a highly poisonous C19-diterpenoid alkaloid identified and isolated from the species of the genus Aconitum. Aconitine is indicated in the treatment of cardiovascular diseases (CVDs) and, due to its neurotoxic effects, is a very effective drug in pain release. A total of 101 relevant scientific papers were manually searched on the Web of Science, Scopus, Science Direct, Google Scholar, PubMed and Dovepress databases and in the books available in the library of the Department of Natural Sciences, the National University of Science and Technology POLITEHNICA Bucharest, Pitesti University Centre, Romania. In combination treatments, aconitine shows antiarrhythmic and anti-inflammatory activity, a synergistic antiproliferative effect and decreased reactive oxygen species (ROS) generation, an improved biodistribution and bioavailability. Additionally, the entrapment of aconitine in engineered nanoparticles represents a promising method for reducing the toxicity of this alkaloid. This review provides, for the first time, a comprehensive picture of the knowledge and research on the synergistic, additive and antagonistic effects of aconitine in combination treatments applied in vivo or in vitro. The summarized studies represent important clues in addressing the multitude of knowledge, which can find their utility in practical and clinical applications.

Effects of schisandra lignans on the absorption of protopanaxadiol-type ginsenosides mediated by P-glycoprotein and protopanaxatriol-type ginsenosides mediated by CYP3A4

ETHNOPHARMACOLOGICAL RELEVANCE

Ginseng Radix et Rhizoma (GRR) and Schisandrae Chinensis Fructus (SCF) are frequently used as herb pairs in traditional herbal formulas especially for the synergetic beneficial effects on lung and heart. Shengmai-yin (SMY), a noted formula, was first published in the traditional Chinese medicine classic named Yixue Qiyuan written by Zhang Yuansu in the Jin Dynasty, and has been used for deficiency of both qi and yin, palpitation, shortness of breath and spontaneous sweating. In SMY, GRR, a sovereign herb, plays an essential role in tonifying lung and supplementing qi, and SCF as an adjuvant herb contributes to the effects of nourishing yin and promoting fluid production, both of which are traditionally used as invigorants in China, Korea, Japan, and Russia. However, the underlying compatibility mechanism of GRR-SCF has remained unknown.

AIM OF THE STUDY

In order to explore the impact and underlying mechanism of schisandra chinensis extract (SCE) on the absorption of ginsenosides Rb1, Rc, Rb2 and Rd belonging to protopanaxdiol (PPD)-type and ginsenosides Rg1 and Re belonging to protopanaxtriol (PPT)-type, pharmacokinetic studies, molecular docking technique and single-pass intestinal perfusion (SPIP) experiment were conducted.

MATERIAL AND METHODS

Preliminarily, pharmacokinetic characteristics of ginseng extract (GE) in the presence and absence of SCE were studied. Thereafter, molecular docking was used to predict whether ginsenosides were P-glycoprotein (P-gp) or cytochrome P450 isoenzyme 3A4 (CYP3A4) substrates. Finally, the effects and underlying mechanism of SCE on the absorption of GE were further investigated by in situ SPIP experiment.

RESULTS

Our findings indicated that SCE could increase exposure in vivo and the intestinal absorption of distinct ginsenosides. Additionally, we found that the PPD-type ginsenosides Rb1, Rc, Rb2, and Rd were substrates for P-gp, and the PPT-type ginsenosides Rg1 and Re were substrates for CYP3A4 rather than P-gp. SCE, which has been found with extensive inhibitory effects on P-gp and CYP3A4, could remarkably promote the intestinal absorption of ginsenosides Rg1, Re, Rb1, Rc, Rb2, and Rd, obtaining similar effects comparable with ketoconazole known as a classic dual inhibitor of P-gp and CYP3A4.

CONCLUSIONS

The study demonstrated that SCE could improve the absorption of GE, and revealed the underlying compatibility mechanism of GRR and SCF from the perspective of P-gp and CYP3A4-mediated interactions to some extent, which provided a certain scientific reference for the compatibility and clinical practice of GRR-SCF as common herb pairs in traditional prescriptions such as SMY. Moreover, this study also furnished a strategy for improving the oral bioavailability of different types of ginsenosides by drug combinations.

Development and Evaluation of a Novel Hyaluronic Acid and Chitosan-modified Phytosome for Co-delivery of Oxymatrine and Glycyrrhizin for Combination Therapy

BACKGROUND

Multidrug resistance (MDR) of cancer cells is a major obstacle to efficient cancer chemotherapy. Combination therapy is expected to enhance the anticancer effect and reverse MDR. Numerous patents involve different kinds of nanoparticles for the co-delivery of multiple chemotherapeutics, but the FDA has approved none.

OBJECTIVE

In this study, oxymatrine (OMT) and glycyrrhizin (GL) were co-loaded into phytosomes as the core of nanocarriers, and the shell was cross-linked with chitosan (CS) and hyaluronic acid (HA) with the capability for the controlled, sequential release and the targeted drug uptake.

METHODS

Phospholipid complexes of OMT and GL (OGPs) were prepared by a solvent evaporation technique and could self-assemble in an aqueous solution to form phytosomes. CS and HA were sequentially coated on the surface of OGPs via electrostatic interactions to obtain CS coated OGPs (CS-OGPs) and HA modified CS-OGPs (HA-CS-OGPs), respectively. The particle size and zeta potential were measured to optimize the formulations. In vitro cytotoxicity and cellular uptake experiments on HepG2 cells were performed to evaluate the anticancer activity.

RESULTS

OGPs were obtained with nano-size around 100 nm, and CS and HA coating on phytosomes could change the particle size and surface potential. The drug loading of OMT and GL showed that the nanocarriers could maintain a fixed ratio of 1:1. The in vitro release experiments indicated the release of OMT and GL was pH-dependent and sequential: the release of OMT from CS-OGPs and HA-CS-OGPs was significantly increased at pH 5.0 compared to the release at pH 7.4, while GL exhibited sustained released from CS-OGPs and HA-CS-OGPs at pH 5.0. Furthermore, in vitro cytotoxicity and cellular uptake experiments on HepG2 cells demonstrated that the co-delivery system based on phytosomes had significant synergistic anti-tumor activities, and the effects were enhanced by CS and HA modification.

CONCLUSION

The delivery of OMT and GL via HA-CS-OGPs might be a promising treatment to reverse MDR in cancer therapy.

Nanostructures in Chinese herbal medicines (CHMs) for potential therapy

With its long clinical history, traditional Chinese medicine (TCM) has gained acceptance for its specific efficacy and safety in the treatment of multiple diseases. Nano-sized materials study of Chinese herbal medicines (CHMs) leads to an increased understanding of assessing TCM therapies, which may be a promising way to illustrate the material basis of CHMs through their processing and extraction. In this review, we provide an overview of the nanostructures of natural and engineered CHMs, including extracted CHMs, polymer nanoparticles, liposomes, micelles, and nanofibers. Subsequently, the applications of these CHM-derived nanostructures to particular diseases are summarized and discussed. Additionally, we discuss the advantages of these nanostructures for studying the therapeutic efficacy of CHMs. Finally, the key challenges and opportunities for the development of these nanostructures are outlined.

Complex components of Shengmai formula interact with organic cation transporter 2 (OCT2) in MDCK cells

ETHNOPHARMACOLOGICAL RELEVANCE

Shengmai formula (SMF) is a well-known Chinese herbal compound preparation, which is utilized extensively for the treatment of myocardial ischemia, arrhythmia and other life-threatening conditions. Our previous researches have shown that some of the active ingredients in SMF can interact with organic anion transport polypeptide 1B1 (OATP1B1), breast cancer resistance protein (BCRP) and organic anion transporter 1 (OAT1), etc. Organic cation transporter 2 (OCT2) is a highly expressed uptake transporter in the kidney, and its interaction with the major active components in SMF remains unclear.

AIM OF THE STUDY

We purposed to explore OCT2-mediated interactions and compatibility mechanisms of the main active compounds in SMF.

MATERIALS AND METHODS

Fifteen active ingredients of SMF, including ginsenoside Rb1, Rd, Re, Rg1, Rf, Ro and Rc, methylophiopogonanone A and B, ophiopogonin D and D', schizandrin A and B, schizandrol A and B, were selected to investigate OCT2-mediated interactions in Madin-Darby cacine kidney (MDCK) cells stably expressing OCT2.

RESULTS

Among the above 15 main active components, only ginsenosides Rd, Re and schizandrin B could significantly inhibit the uptake of 4-(4-(dimethylamino)styryl)-N-methyl pyridiniumiodide (ASP⁺), a classical substrate of OCT2. Ginsenoside Rb1 and methylophiopogonanone A can be transported by MDCK-OCT2 cells, and their uptake was significantly reduced when OCT2 inhibitor decynium-22 was added. Ginsenoside Rd could remarkably reduce the uptake of methylophiopogonanone A and ginsenoside Rb1 by OCT2, ginsenoside Re only decreased the uptake of ginsenoside Rb1, while schizandrin B had no effect on the uptake of both.

CONCLUSIONS

OCT2 mediates the interaction of the major active components in SMF. Ginsenosides Rd, Re and schizandrin B are the potential inhibitors of OCT2, while ginsenosides Rb1 and methylophiopogonanone A are the potential substrates of OCT2. There is an OCT2-mediated compatibility mechanism among these active ingredients of SMF.

Effects of hypoxia on the expression and function of P-gp in Caco-2 cells

OBJECTIVES

Hypoxia can alter the oral bioavailability of drugs, including various substrates (drugs) of P-glycoprotein (P-gp), suggesting that hypoxia may affect the function of P-gp in intestinal epithelial cells. Currently, Caco-2 monolayer model is the classic model for studying the function of intestinal epithelial P-gp. This study combines the Caco-2 monolayer model with hypoxia to investigate the effects of hypoxia on the expression and function of P-gp in Caco-2 cells, which helps to elucidate the mechanism of changes in drug transport on intestinal epithelial cells in high-altitude hypoxia environment.

METHODS

Normally cultured Caco-2 cells were cultured in 1% oxygen concentration for 24, 48, and 72 h, respectively. After the extraction of the membrane proteins, the levels of P-gp were measured by Western blotting. The hypoxia time, with the most significant change of P-gp expression, was selected as the subsequent study condition. After culturing Caco-2 cells in transwell cells for 21 days and establishing a Caco-2 monolayer model, they were divided into a normoxic control group and a hypoxic group. The normoxic control group was continuously cultured in normal condition for 72 h, while the hypoxic group was incubated for 72 h in 1% oxygen concentration. The integrity and polarability of Caco-2 cells monolayer were evaluated by transepithelial electrical resistance (TEER), apparent permeability (Papp) of lucifer yellow, the activity of alkaline phosphatase (AKP), and microvilli morphology and tight junction structure under transmission electron microscope. Then, the Papp of rhodamine 123 (Rh123), a kind of P-gp specific substrate, was detected and the efflux rate was calculated. The Caco-2 cell monolayer, culturing at plastic flasks, was incubated for 72 h in 1% oxygen concentration, the expression level of P-gp was detected.

RESULTS

P-gp was decreased in Caco-2 cells with 1% oxygen concentration, especially the duration of 72 h (P<0.01). In hypoxic group, the TEER of monolayer was more than 400 Ω·cm2, the Papp of lucifer yellow was less than 5×10-7 cm/s, and the ratio of AKP activity between apical side and basal side was greater than 3. The establishment of Caco-2 monolayer model was successful, and hypoxia treatment did not affect the integrity and polarization state of the model. Compared with the normoxic control group, the efflux rate of Rh123 was significantly reduced in Caco-2 cell monolayer of the hypoxic group (P<0.01). Hypoxia reduced the expression of P-gp in Caco-2 cell monolayer (P<0.01).

CONCLUSIONS

Hypoxia inhibits P-gp function in Caco-2 cells, which may be related to the decreased P-gp level.

Detoxification mechanisms of ginseng to aconite: A review

ETHNOPHARMACOLOGICAL RELEVANCE

Aconite (Fuzi, FZ), the processed root tuber of Aconitum carmichaelii Debx., is utilized as a classic medicine to treat diseases of the cardiovascular system and immune system. Resulting from the narrow margin of safety between a therapeutic dose and a toxic dose, FZ often causes cardiotoxicity including hypotension, palpitation, and bradycardia. Contributing to the detoxification effects of the other famous herbal medicine ginseng (Renshen, RS), which is the dried root and rhizome of Panax ginseng C. A. Meyer, people broadly combine FZ and RS as compatibility more than 1800 years to attenuate the toxicity of FZ. However, the systematic detoxification mechanisms of RS to FZ have not been fully revealed.

AIM OF THE REVIEW

Aiming to provide a comprehensive interpretation of the attenuation processes of FZ via RS, this review summarizes the up-to-date information about regulatory mechanisms of RS to FZ to shed the light on the essence of detoxification.

MATERIALS AND METHODS

Literature was searched in electronic databases, including PubMed, Web of Science ScienceDirect, Google Scholar, CNKI and WanFang Data. Relevant studies on detoxification mechanisms were included while irrelevant and duplicate studies were excluded. According to the study design, subject, intervention regime, outcome, first author and year of publication of included data, detoxification mechanisms of RS to FZ were summarized and visualized.

RESULTS

A total of 144 studies were identified through databases from their inception up to Oct. 2022. Included information indicated that diester-diterpenoid alkaloids (DDAs) were the main toxic substances of FZ. The main mechanisms that RS attenuates the toxicity of FZ were transforming toxic compounds of FZ, affecting the absorption and metabolism of FZ as well as the FZ-induced cell toxicity alleviation.

CONCLUSION

FZ, as a famous traditional Chinese medicine, has good prospects for utilization. The narrow margin of safety between a therapeutic dose and a toxic dose of FZ limits its clinical effect and safety while RS is always combined with FZ to alleviate its toxicity. However, mechanisms responsible for the detoxification process have not been well identified. Therefore, detoxification mechanisms of RS to FZ are reviewed to ensure the safety and effectiveness of FZ.

Research progress of traditional Chinese medicine as sensitizer in reversing chemoresistance of colorectal cancer

In recent years, the incidences and mortalities from colorectal cancer (CRC) have been increasing; therefore, there is an urgent need to discover newer drugs that enhance drug sensitivity and reverse drug tolerance in CRC treatment. With this view, the current study focuses on understanding the mechanism of CRC chemoresistance to the drug as well as exploring the potential of different traditional Chinese medicine (TCM) in restoring the sensitivity of CRC to chemotherapeutic drugs. Moreover, the mechanism involved in restoring sensitivity, such as by acting on the target of traditional chemical drugs, assisting drug activation, increasing intracellular accumulation of anticancer drugs, improving tumor microenvironment, relieving immunosuppression, and erasing reversible modification like methylation, have been thoroughly discussed. Furthermore, the effect of TCM along with anticancer drugs in reducing toxicity, increasing efficiency, mediating new ways of cell death, and effectively blocking the drug resistance mechanism has been studied. We aimed to explore the potential of TCM as a sensitizer of anti-CRC drugs for the development of a new natural, less-toxic, and highly effective sensitizer to CRC chemoresistance.

Herb-drug interaction between Shaoyao-Gancao-Fuzi decoction and tofacitinib via CYP450 enzymes

ETHNOPHARMACOLOGY RELEVANCE

Shaoyao-Gancao-Fuzi decoction (SGFD), a well-known traditional Chinese medicine formula, was originally described in "Treatise on Febrile Diseases" and has been extensively used to dispel wind, eliminate dampness and treat paralysis. It is widely used for the treatment of rheumatoid arthritis in clinic. However, the effect of SGFD on the activity of cytochrome P450 enzymes (CYP450s) and the herb-drug interactions are rarely studied.

OBJECTIVE

The aim of this study was to investigate the effect of SGFD on the activity of CYP450s and evaluate the potential herb-drug interactions between SGFD and tofacitinib, commonly used disease-modifying antirheumatic drug in rheumatoid arthritis.

MATERIALS AND METHODS

The cocktail approach was employed to assess the effect of SGFD on the activity of CYP1A2, 3A4, 2A6, 2E1, and 2C9. The pharmacokinetic profile of oral administration of tofacitinib in rats after two weeks of treatment with SGFD was investigated. RT-qPCR and molecular docking were performed to unveil the underlying mechanism of the herb-drug interaction.

RESULTS

SGFD had no effect on the activities of CYP2E1 and 2C9, had a weak effect on CYP2A6, and had activatory effect on CYP1A2. However, it had a dramatically inhibitory effect on the activity of CYP3A4. Simultaneously, the values of C_max and AUC_0-∞ of tofacitinib were obviously increased after treatment with SGFD for 14 days. The mechanism study manifested that SGFD significantly reduced the gene transcription of CYP3A. Molecular docking work confirmed that the inhibitory activity of glycyrrhetinic acid, glycyrrhizic acid and liquiritin, the main ingredients of SGFD, occurred by occupying the active sites of CYP3A4 and by making favorable interactions with its key residues.

CONCLUSIONS

The system exposure of tofacitinib was increased by SGFD. SGFD could affect the activity and gene expression of the key metabolic enzyme CYP3A. These findings give a clear understanding to predict herb-drug interaction of SGFD for safe clinical use in future.

Advances on pharmacology and toxicology of aconitine

Aconitum alkaloids are considered to be the characteristic bioactive ingredients of Aconitum species, which are widely applied to the treatment of diverse diseases, and aconitine (AC) is found in most Aconitum plants. Research evidence shows that low-dose AC has a good therapeutic potential in heart failure, myocardial infarction, neuroinflammatory diseases, rheumatic diseases, and tumors, which has become one of the hotspots in global research in recent years. However, the cardiotoxicity and neurotoxicity of AC have also attracted extensive attention. Excessive use of AC always induces ventricular tachyarrhythmia and heart arrest, even can be potentially lethal. Therefore, AC cannot simply be regarded as a good medicine or a toxicant, but its underlying curative and toxic properties remained chaos. In order to dig the unique pharmacological value of AC while preventing its toxicity, the pharmacological activities and toxic effects of AC were summarized in this paper, providing new insight into the safe and effective use of AC in clinical practice.

Hematological and Histopathological Effects of Subacute Aconitine Poisoning in Mouse

Aconitine is the principal toxic ingredient of Aconitum, which can cause systemic poisoning involving multiple organs and systems after animal ingestion. The purpose of this study was to investigate the effects of aconitine on hematological indices and histological changes in mice. One hundred twenty mice were divided into a control group (normal saline), low-dose group (0.14 μmol/L), middle-dose group (0.28 μmol/L) and high-dose group (0.56 μmol/L), which were continuously lavaged for 30 days. The blood of 10 mice were collected randomly and analyzed by group at the 10th, 20th, and 30th days, and some tissues were collected and stained with hematoxylin-eosin to observe histological changes at the 30th day. Compared with the control group, the organ coefficient (%) of liver, spleen, lungs, and brain of the high-dose group were significantly increased (p < 0.05 or p < 0.01). WBC and Gran initially decreased and then increased in each poisoning group, with significant differences in the high-dose group (p < 0.05 or p < 0.01). RBC, HGB, HCT, and PLT decreased continuously in all groups except the low-dose group at the 20th and 30th days (p < 0.05 or p < 0.01). Moreover, BUN, ALT and AST increased in each poisoning group, in comparison with the control group, with significant differences except for the low-dose group (p < 0.05 or p < 0.01). CRE initially increased and then decreased, the TP and ALB decreased, with significant differences observed in the high-dose and middle-dose groups (p < 0.05). All the mice in the poison-treated groups showed varying degrees of histopathological changes such as degeneration and necrosis of tissues, especially heart and cerebellum. Our data suggest that different doses of aconitine have remarkable effects on hematological and histopathological changes in mice, in a significant time and dose-effect relationship.

Approaches to minimize the effects of P-glycoprotein in drug transport: A review

P-glycoprotein (P-gp) is a transporter protein that is come under the ATP binding cassette family of proteins. It is situated on the surface of the intestine epithelium, where P-gp substrate binds to the transporter and is pumped into the intestine lumen by the ATP-driven energy-dependent process. In this review, we summarize the role of the P-gp efflux transporter situated on the intestine, the clinical importance of P-gp related drug interactions, and approaches to minimize the effect of P-gp in drug transport. This review also focuses on the impact of P-gp on the bioavailability of the orally administered drug. Many drug's oral bioavailabilities can improve by concomitant use of P-gp inhibitors. Multidrug resistance are reduced by using some naturally occurring compounds obtained from plants and several synthetic P-gp inhibitors. Formulation strategies, one of the most important approaches to mimic the P-gp transporter's action, finally enhancing the oral bioavailability of the drug by inhibiting its P-gp efflux. Vitamin E TPGS, Gelucire 44/14 and other pharmaceutical/formulation excipients inhibit the P-gp efflux. A prodrug approach might be a useful strategy to overcome drug resistance. Prodrug helps to enhance the solubility or alter the pharmacokinetic properties but does not diminish the pharmacological action.

Aconitine induces cell apoptosis via mitochondria and death receptor signaling pathways in hippocampus cell line

Aconitine is a plant toxin derived from aconitum genus and well known for its neurological and vascular toxicity. However, the mechanism of toxicity on the growth and apoptosis of the neurological cells has not been well investigated. In this study, we used HT22 cell lines derived from hippocampus to explore the mechanism. We began with examination of the viability and DA (dopamine) contents of cells treated with different dose of aconitine. In this study, we investigated the role of apoptosis in AC-induced HT22 cells. Our results showed that aconitine inhibited HT22 cells growth and increased DA contents in a dose dependent manner. Aconitine treatment induced apoptosis in HT22 cells and we found aconitine induced apoptosis by upregulating the expression of Bax, Cyto c, Apaf-1, Caspase9, Fas, Fas-L, Fadd, Caspase8, Caspase3 with concomitant decreasing of Bcl-2 and Bid expression. Collectively, results suggest that aconitine induce apoptosis through mitochondrial-mediated and death receptor signaling pathways in HT22 cells.

Influence of verapamil on the pharmacokinetics of rotundic acid in rats and its potential mechanism

CONTEXT

Rotundic acid (RA), a plant-derived pentacyclic triterpene acid, has been reported to possess extensive pharmacological activities. The poor bioavailability limits its further development and potential clinic application.

OBJECTIVE

To clarify the potential mechanism for poor oral bioavailability.

MATERIALS AND METHODS

The single-dose pharmacokinetics of orally administered RA (10 mg/kg) in Sprague-Dawley rats without or with verapamil (25 or 50 mg/kg) were investigated. Additionally, MDCKII-MDR1 and Caco-2 cell monolayers, five recombinant human cytochrome P450 (rhCYP) enzymes (1A2, 2C8, 2C9, 2D6 and 3A4), and rat liver microsomes were also conducted to investigate its potential mechanism.

RESULTS

Verapamil could significantly affect the plasma concentration of RA. Co-administered verapamil at 25 and 50 mg/kg, the AUC_0-∞ increased from 432 ± 64.2 to 539 ± 53.6 and 836 ± 116 ng × h/mL, respectively, and the oral clearance decreased from 23.6 ± 3.50 to 18.7 ± 1.85 and 12.2 ± 1.85 L/h/kg, respectively. The MDCKII-MDR1 cell assay showed that RA might be a P-gp substrate. The rhCYPs experiments indicated that RA was mainly metabolized by CYP3A4. Additionally, verapamil could increase the absorption of RA by inhibiting the activity of P-gp, and slow down the intrinsic clearance of RA from 48.5 ± 3.18 to 12.0 ± 1.06 µL/min/mg protein.

DISCUSSION AND CONCLUSIONS

These findings indicated that verapamil could significantly affect the pharmacokinetic profiles of RA in rats. It was demonstrated that P-gp and CYP3A were involved in the transport and metabolism of RA, which might contribute to the low oral bioavailability of RA.

Absolute bioavailability, dose proportionality, and tissue distribution of rotundic acid in rats based on validated LC-QqQ-MS/MS method

Rotundic acid (RA), an ursane-type pentacyclic triterpene acid isolated from the dried barks of Ilex rotunda Thunb. (Aquifoliaceae), possesses diverse bioactivities. To further study its pharmacokinetics, a simple and sensitive liquid chromatography with triple quadrupole mass spectrometry (LC-QqQ-MS/MS) method was developed and validated to quantify RA concentration in rat plasma and tissue using etofesalamide as an internal standard (IS). Plasma and tissue samples were subjected to one-step protein precipitation. Chromatographic separation was achieved on a ZORBAX Eclipse XDB-C₁₈ column (4.6 mm × 50 mm, 5 μm) under gradient conditions with eluents of methanol:acetonitrile (1:1, V/V) and 5 mM ammonium formate:methanol (9:1, V/V) at 0.5 mL/min. Multiple reaction monitoring transitions were performed at m/z 487.30 → 437.30 for RA and m/z 256.10 → 227.10 for IS in the negative mode. The developed LC-QqQ-MS/MS method exhibited good linearity (2–500 ng/mL) and was fully validated in accordance with U.S. Food and Drug Administration bioanalytical guidelines. Dose proportionality and bioavailability in rats were determined by comparing pharmacokinetic data after single oral (10, 20, and 40 mg/kg) and intravenous (10 mg/kg) administration of RA. Tissue distribution was studied following oral administration at 20 mg/kg. The results showed that the absolute bioavailability of RA after administration at different doses ranged from 16.1% to 19.4%. RA showed good dose proportionality over a dose range of 10–40 mg/kg. RA was rapidly absorbed in a dose-dependent manner and highly distributed in the liver. In conclusion, this study is the first to systematically elucidate the absorption and distribution characteristics of RA in rats, which can provide additional information for further development and evaluation of RA in drug metabolism and pharmacokinetic studies.

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A simple, rapid, and sensitive LC-QqQ-MS/MS method was developed and validated for RA quantification in rat plasma and tissue.

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Absolute bioavailability of RA was calculated to range from 16.1% to 19.4%.

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Dose proportionality and tissue distribution of RA were assessed for in rats.

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RA showed good dose proportionality over a dose range of 10–40 mg/kg.

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RA was rapidly and extensively distributed and exhibited the highest concentration in the liver after oral administration.

Comparative HPLC-MS/MS-based pharmacokinetic studies of multiple diterpenoid alkaloids following the administration of Zhenwu Tang and Radix Aconiti Lateralis Praeparata extracts to rats

Abstracts Zhenwu Tang (ZWT) is a traditional Chinese medicine that is primarily composed of Radix Aconiti Lateralis Praeparata (FZ) and diterpenoid alkaloids are believed to be the pharmacologically active compounds of ZWT. In this study, the pharmacokinetic profiles of hypaconitine, mesaconitine, aconitine, benzoylmesaconitine, benzoylaconitine, and benzoylhypacoitine were assessed in rats following intragastric ZWT administration. Furthermore, differences in the pharmacokinetic profiles of these six alkaloids were assessed as a function of rat sex and the administration of ZWT or FZ extracts to these animals. Plasma levels of these alkaloids were quantified via HPLC-MS/MS. Significant differences in key pharmacokinetic parameters were observed when comparing rats administered FZ or ZWT. Relative to FZ extract treatment, ZWT administration was associated with C_max and AUC_0-∞ values of benzoylmesaconitine that were about 3.5 and 5.5 times higher. Considerable variations in hypaconitine pharmacokinetic parameters were also revealed between female and male rats. The C_max and AUC_0-∞ of hypaconitine were about 2.5- and 2.7-fold elevated in female rats in comparison with male rats. These results suggested that the other compounds within ZWT can enhance the absorption of benzoylmesaconitine, while hypaconitine exhibits higher bioavailability in female rats, as compared with male rats.

The Effects of Traditional Chinese Medicine on P-Glycoprotein-Mediated Multidrug Resistance and Approaches for Studying the Herb-P-Glycoprotein Interactions

As a member of the ATP-dependent membrane transport proteins, P-Glycoprotein (P-gp) is known to pump substrates out of cells using an ATP-dependent mechanism. The overexpression of P-gp in tumor cells reduces the intracellular drug concentrations, which decreases the efficacy of extensive antitumor drugs and leads to multidrug resistance (MDR) clinically. The combination of anticancer drugs with P-gp inhibitor has been an attractive and promising strategy to reverse MDR in cancer treatment. However, nonspecific or nonselective distribution of P-gp inhibitors to nontarget organs is one of the most fatal shortcomings in clinical application. Thus, there is an urgent need for effective and nontoxic MDR reversal agents, particularly in P-gp-mediated MDR. Traditional Chinese medicine (TCM) natural products may prove less toxic for use in P-gp inhibition to promote MDR reversal. P-gp modulatory effects have been previously demonstrated using selected TCM, including the flavonoid, alkaloid, terpenoid, coumarin, and quinonoid compounds, and some Chinese medicine extracts. Moreover, the approaches for screening active components from TCM are necessary, and these approaches face challenges. At present, the approaches to study the interaction between TCM and P-gp are divided into in vitro, in vivo, and in silico methods. This review will provide an overview and update on the role of TCM in overcoming P-gp-mediated MDR and the approaches to study the interaction between TCM and P-gp. SIGNIFICANCE STATEMENT: This review summarized some traditional Chinese medicines identified to have a modulatory effect on P-gp, including flavonoids, alkaloids, terpenoids, coumarins, quinonoid compounds, and some Chinese medicine extracts, and it introduced possible mechanisms. The approaches to study the interaction between TCM and P-gp are divided into in vitro, in vivo, and in silico methods.