Transporter modulation by Chinese herbal medicines and its mediated pharmacokinetic herb–drug interactions

Mechanisms of intestinal pharmacokinetic natural product-drug interactions

The growing co-consumption of botanical natural products with conventional medications has intensified the need to understand potential effects on drug safety and efficacy. This review delves into the intricacies of intestinal pharmacokinetic interactions between botanical natural products and drugs, such as alterations in drug solubility, permeability, transporter activity, and enzyme-mediated metabolism. It emphasizes the importance of understanding how drug solubility, dissolution, and osmolality interplay with botanical constituents in the gastrointestinal tract, potentially altering drug absorption and systemic exposure. Unlike reviews that focus primarily on enzyme and transporter mechanisms, this article highlights the lesser known but equally important mechanisms of interaction. Applying the Biopharmaceutics Drug Disposition Classification System (BDDCS) can serve as a framework for predicting and understanding these interactions. Through a comprehensive examination of specific botanical natural products such as byakkokaninjinto, green tea catechins, goldenseal, spinach extract, and quercetin, we illustrate the diversity of these interactions and their dependence on the physicochemical properties of the drug and the botanical constituents involved. This understanding is vital for healthcare professionals to effectively anticipate and manage potential natural product-drug interactions, ensuring optimal patient therapeutic outcomes. By exploring these emerging mechanisms, we aim to broaden the scope of natural product-drug interaction research and encourage comprehensive studies to better elucidate complex mechanisms.

Herb-drug interactions between Panax notoginseng or its biologically active compounds and therapeutic drugs: A comprehensive pharmacodynamic and pharmacokinetic review

ETHNOPHARMACOLOGICAL RELEVANCE

Herbs, along with the use of herb-drug interactions (HDIs) to combat diseases, are increasing in popularity worldwide. HDIs have two effects: favorable interactions that tend to improve therapeutic outcomes and/or minimize the toxic effects of drugs, and unfavorable interactions aggravating the condition of patients. Panax notoginseng (Burk.) F.H. Chen is a medicinal plant that has long been commonly used in traditional Chinese medicine to reduce swelling, relieve pain, clear blood stasis, and stop bleeding. Numerous studies have demonstrated the existence of intricate pharmacodynamic (PD) and pharmacokinetic (PK) interactions between P. notoginseng and conventional drugs. However, these HDIs have not been systematically summarized.

AIM OF THE REVIEW

To collect the available literature on the combined applications of P. notoginseng and drugs published from 2005 to 2022 and summarize the molecular mechanisms of interactions to circumvent the potential risks of combination therapy.

MATERIALS AND METHODS

This work was conducted by searching PubMed, Scopus, Web of Science, and CNKI databases. The search terms included "notoginseng", "Sanqi", "drug interaction," "synergy/synergistic", "combination/combine", "enzyme", "CYP", and "transporter".

RESULTS

P. notoginseng and its bioactive ingredients interact synergistically with numerous drugs, including anticancer, antiplatelet, and antimicrobial agents, to surmount drug resistance and side effects. This review elaborates on the molecular mechanisms of the PD processed involved. P. notoginseng shapes the PK processes of the absorption, distribution, metabolism, and excretion of other drugs by regulating metabolic enzymes and transporters, mainly cytochrome P450 enzymes and P-glycoprotein. This effect is a red flag for drugs with a narrow therapeutic window. Notably, amphipathic saponins in P. notoginseng act as auxiliary materials in drug delivery systems to enhance drug solubility and absorption and represent a new entry point for studying interactions.

CONCLUSION

This article provides a comprehensive overview of HDIs by analyzing the results of the in vivo and in vitro studies on P. notoginseng and its bioactive components. The knowledge presented here offers a scientific guideline for investigating the clinical importance of combination therapies. Physicians and patients need information on possible interactions between P. notoginseng and other drugs, and this review can help them make scientific predictions regarding the consequences of combination treatments.

Genetic analysis of Vibrio alginolyticus challenged by Fructus schisandrae reveals the mechanism of virulence genes

Due to the abusive use of antibiotics, bacterial resistance has become a global problem and poses severe threats to aquaculture. The drug-resistant diseases caused by Vibrio alginolyticus have caused significant economic losses to cultured marine fish. Fructus schisandrae is used to treat inflammatory diseases in China and Japan. There have been no reports of bacterial molecular mechanisms associated with F. schisandrae stress. In this study, the inhibiting effect of F. schisandrae on the growth of V. alginolyticus was detected to understand response mechanisms at the molecular level. The antibacterial tests were analyzed via next-generation deep sequencing technology (RNA sequencing, RNA-seq). Wild V. alginolyticus (CK) was compared with V. alginolyticus, F. schisandrae incubated for 2 h, and V. alginolyticus, F. schisandrae incubated for 4 h. Our results revealed that there were 582 genes (236 upregulated and 346 downregulated) and 1068 genes (376 upregulated and 692 downregulated), respectively. Differentially expressed genes (DEGs) were involved in the following functional categories: metabolic process, single-organism process, catalytic activity, cellular process, binding, membrane, cell part, cell, and localization. FS_2 h was compared with FS_4 h, and 21 genes (14 upregulated and 7 downregulated) were obtained. The RNA-seq results were validated by detecting the expression levels of 13 genes using quantitative real-time polymerase chain reaction (qRT-PCR). The qRT-PCR results matched those of the sequencing, which reinforced the reliability of the RNA-seq. The results revealed the transcriptional response of V. alginolyticus to F. schisandrae, which will provide new ideas for studying V. alginolyticus' complex virulence molecular mechanism and the possibility of developing Schisandra to prevent and treat drug-resistant diseases.

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.

Interaction of the main active components in Shengmai formula mediated by organic anion transporter 1 (OAT1)

ETHNOPHARMACOLOGICAL RELEVANCE

Shengmai formula (SMF) is a classical traditional Chinese medicine prescription, which is widely used in the treatment of cardiovascular and cerebrovascular diseases. Our previous studies have demonstrated that some components in SMF can interact with each other through breast cancer resistance protein, sodium taurocholate co-transporting polypeptide, organic anion transporting polypeptide 1B1 and 1B3. Organic anion transporter 1 (OAT1) is highly expressed in kidney, mediating the elimination of many endogenous and exogenous substances. However, the interaction between the main active components in SMF and OAT1 is not clear.

AIM OF THE STUDY

This study aimed to investigate the interactions of the major bioactive components in SMF mediated by OAT1.

MATERIALS AND METHODS

Four main fractions, namely, ginseng total saponins (GTS), ophiopogon total saponins (OTS), ophiopogon total flavonoids (OTF), fructus schisandrae total lignans (STL), and 12 active components, namely, ginsenoside Rg1, Re, Rd and Rb1, ophiopogonin D and D', methylophiopogonanone A and B, schizandrol A and B, schizandrin A and B, were selected to explore the interactions of SMF with OAT1 using cell and rat models.

RESULTS

The above four main fractions in SMF all exhibited inhibitory effects on the uptake of 6-carboxyfluorescein (6-CF), a classic substrate of OAT1. Among the 12 main effective components, only ginsenoside Re, Rd, and methylophiopogonanone A showed inhibition of 6-CF uptake. Additionally, we found that schizandrin B was transported by HEK293-OAT1 cells, and schizandrin B uptake was markedly inhibited by GTS, OTS, OTF, ginsenoside Re, Rd, and methylophiopogonanone A. In rats, ginsenoside Re, Rd, and methylophiopogonanone A jointly increased the AUC_(0-t), AUC_(0-∞), and C_max of schizandrin B, but they decreased its clearance in plasma and excretion in urine.

CONCLUSIONS

Ginsenoside Re, Rd, and methylophiopogonanone A were the potential inhibitors of OAT1, and may interact with some drugs serving as OAT1 substrates clinically. Schizandrin B was a potential OAT1 substrate, and its OAT1-mediated transport was inhibited by ginsenoside Re, Rd, and methylophiopogonanone A. OAT1-mediated interactions of the main active components in SMF can be regarded as one of the important compatibility mechanisms of traditional Chinese medicine preparations.

Advances in Pharmacokinetic Mechanisms of Transporter-Mediated Herb-Drug Interactions

As the use of herbs has become more popular worldwide, there are increasing reports of herb-drug interactions (HDIs) following the combination of herbs and drugs. The active components of herbs are complex and have a variety of pharmacological activities, which inevitably affect changes in the pharmacokinetics of chemical drugs in vivo. The absorption, distribution, metabolism, and excretion of drugs in vivo are closely related to the expression of drug transporters. When the active components of herbs inhibit or induce the expression of transporters, this can cause changes in substrate pharmacokinetics, resulting in changes in the efficacy and toxicity of drugs. In this article, the tissue distribution and physiological functions of drug transporters are summarized through literature retrieval, and the effects of herbs on drug transporters and the possible mechanism of HDIs are analyzed and discussed in order to provide ideas and a reference for further guiding of safe clinical drug use.

Effect of major components of Tripterygium wilfordii Hook. f on the uptake function of organic anion transporting polypeptide 1B1

Organic anion transporting polypeptide 1B1 (OATP1B1), which is specifically expressed at the basolateral membrane of human hepatocytes, is well recognized as the key determinant in the pharmacokinetics of a wide variety of drugs and considered as an important drug-drug interaction (DDI) site. Triptergium wilfordii Hook. f. (TWHF) is a traditional Chinese medicine that has a long history in treating diseases and more pharmacological effects were demonstrated recently. Components of TWHF mainly belong to the groups of alkaloids, diterpenoids, and triterpenoids. However, whether TWHF constituents are involved in herb-drug interaction (HDI) remains largely unknown. In the present study, we investigated the effect of four major components of TWHF, i.e. Triptolide (TPL), Celastrol (CL), and two alkaloids Wilforine (WFR) and Wilforgine (WFG) on the function of OATP1B1. It was found that co-incubation of these compounds greatly inhibited the uptake function of OATP1B1, with WFG (IC₅₀ = 3.63 ± 0.61 μM) and WFR (IC₅₀ = 3.91 ± 0.30 μM) showing higher inhibitory potency than TPL (IC₅₀ = 184 ± 36 μM) and CL (IC₅₀ = 448 ± 81 μM). Kinetic analysis revealed that co-incubation of WFG or WFR led to the reduction of both Km and Vmax of the DCF uptake. On the other hand, pre-incubation of WFG or WFR increased Km value of OATP1B1; while CL affected both Km and Vmax. In conclusion, co- and pre-incubation of the tested TWHF components inhibited OATP1B1 activity in different manners. Although co-incubation of WFG and WFR did not seem to directly compete with the substrates, pre-incubation of these alkaloids may alter the substrate-transporter interaction.

Pharmacokinetics and tissue distribution study of 18 bioactive components in healthy and chronic heart failure rats after oral administration of Qi-Shen-Ke-Li formula using ultra-high-performance liquid chromatography/triple quadrupole mass spectrometry

RATIONALE

Qi-Shen-Ke-Li (QSKL) is a traditional Chinese formula used in clinical practice to treat chronic heart failure (CHF) in humans. To rationalize the use of this formula in clinical practice, the pharmacokinetics and tissue distribution in rats after oral administration of QSKL were investigated using ultra-high-performance liquid chromatography/triple quadrupole mass spectrometry (UHPLC/TQ-MS).

METHODS

The CHF model was induced by intraperitoneal injection of isoprenaline (ISO; also known as isoproterenol) and evaluated by HE staining and brain natriuretic peptide (BNP) measurement. The UHPLC/TQ-MS method was then applied to determine the concentrations of 18 bioactive components in rat plasma and tissues of heathy and CHF rats after oral administration of QSKL. This was followed by investigating the pharmacokinetics and tissue distribution profiles of these bioactive compounds in the heathy and CHF rats.

RESULTS

The pharmacokinetics results showed that the duration time of two compounds was prolonged, the absorption rate of four compounds was accelerated, and the bioavailability of four compounds was increased in the CHF rats compared with the healthy rats. Meanwhile, the tissue distribution results showed that the QSKL formula could be distributed rapidly and widely in different rat tissues. The bioavailability of eight compounds in the liver was enhanced in CHF rats. This suggested that the drug/toxic effects should be considered in clinical practice, as drug-drug interactions might occur in liver metabolism during the drug combination.

CONCLUSIONS

The pharmacokinetic profiles and tissue distribution of 18 bioactive compounds in QSKL are altered by the CHF status. This study provides insight for better clinical applications of this formula in the future and lays the foundation for the development of a new drug for chronic heart failure based on the QSKL formula.

Impacts of Drug Interactions on Pharmacokinetics and the Brain Transporters: A Recent Review of Natural Compound-Drug Interactions in Brain Disorders

Natural compounds such as herbal medicines and/or phyto-compounds from foods, have frequently been used to exert synergistic therapeutic effects with anti-brain disorder drugs, supplement the effects of nutrients, and boost the immune system. However, co-administration of natural compounds with the drugs can cause synergistic toxicity or impeditive drug interactions due to changes in pharmacokinetic properties (e.g., absorption, metabolism, and excretion) and various drug transporters, particularly brain transporters. In this review, natural compound–drug interactions (NDIs), which can occur during the treatment of brain disorders, are emphasized from the perspective of pharmacokinetics and cellular transport. In addition, the challenges emanating from NDIs and recent approaches are discussed.

Evaluation of inhibitors of intestinal UDP-glucuronosyltransferases 1A8 and 1A10 using raloxifene as a substrate in Caco-2 cells: Studies with four flavonoids of Scutellaria baicalensis

UDP glucuronosyltransferases (UGTs) of the gastrointestinal tract play a crucial role in protection against the toxic effects of xenobiotics in the environment. UGTs such as UGT1A8 and UGT1A10 are predominantly expressed in gastrointestinal tissues. In this study, we examined the phase II metabolism of raloxifene in differentiated Caco-2 monolayers by inducing UGT1A8 and UGT1A10 expression in these cells. The present study evaluated the following four flavonoids of Scutellaria baicalensis as model herbal compounds: scutellarein, salvigenin, baicalein, and wogonin. All test compounds, endpoint substrates, and their metabolites were quantified using liquid chromatography and high-resolution mass spectrometry. The transepithelial electrical resistance values for the individual compounds were comparable regardless of whether they were measured individually. Salvigenin significantly inhibited UGT1A8 and UGT1A10 activities in a concentration-dependent manner. All individual compounds except scutellarein inhibited UGT1A8 and UGT1A10 activity at a concentration of 100 μM. In addition, all individual flavonoids at 100 μM, except wogonin, significantly increased the amount of raloxifene in the basolateral chambers. The positive control, canagliflozin, significantly inhibited both UGT1A8 and UGT1A10 activities. These findings suggest that the Caco-2 assay can be utilized for identifying UGT1A8 and UGT1A10 inhibitors and indicate the potential of salvigenin for enhancing the pharmacological effects of UGT substrate drugs.

Chemical molecular-based approach to overcome multidrug resistance in cancer by targeting P-glycoprotein (P-gp)

Multidrug resistance (MDR) remains one of the major impediments for efficacious cancer chemotherapy. Increased efflux of multiple chemotherapeutic drugs by transmembrane ATP-binding cassette (ABC) transporter superfamily is considered one of the primary causes for cancer MDR, in which the role of P-glycoprotein (P-gp/ABCB1) has been most well-established. The clinical co-administration of P-gp drug efflux inhibitors, in combination with anticancer drugs which are P-gp transport substrates, was considered to be a treatment modality to surmount MDR in anticancer therapy by blocking P-gp-mediated multidrug efflux. Extensive attempts have been carried out to screen for sets of nontoxic, selective, and efficacious P-gp efflux inhibitors. In this review, we highlight the recent achievements in drug design, characterization, structure-activity relationship (SAR) studies, and mechanisms of action of the newly synthetic, potent small molecules P-gp inhibitors in the past 5 years. The development of P-gp inhibitors will increase our knowledge of the mechanisms and functions of P-gp-mediated drug efflux which will benefit drug discovery and clinical cancer therapeutics where P-gp transporter overexpression has been implicated in MDR.

The Development and Validation of a Novel "Dual Cocktail" Probe for Cytochrome P450s and Transporter Functions to Evaluate Pharmacokinetic Drug-Drug and Herb-Drug Interactions

This study was designed to develop and validate a 10 probe drug cocktail named "Dual Cocktail", composed of caffeine (Cyp1a2 in rat and CYP1A2 in human, 1 mg/kg), diclofenac (Cyp2c11 in rat and CYP2C9 in human, 2 mg/kg), omeprazole (Cyp2c11 in rat and CYP2C19 in human, 2 mg/kg), dextromethorphan (Cyp2d2 in rat and CYP2D6 in human, 10 mg/kg), nifedipine (Cyp3a1 in rat and CYP3A4 in human, 0.5 mg/kg), metformin (Oct1/2 in rat and OCT1/2 in human, 0.5 mg/kg), furosemide (Oat1/3 in rat and OAT1/3 in human, 0.1 mg/kg), valsartan (Oatp2 in rat and OATP1B1/1B3 in human, 0.2 mg/kg), digoxin (P-gp in rat and human, 2 mg/kg), and methotrexate (Mrp2 in rat and MRP2 in human, 0.5 mg/kg), for the evaluation of pharmacokinetic drug-drug and herb-drug interactions through the modulation of a representative panel of CYP enzymes or transporters in rats. To ensure no interaction among the ten probe substrates, we developed a 2-step evaluation protocol. In the first step, the pharmacokinetic properties of five individual CYP probe substrates and five individual transporter substrates were compared with the pharmacokinetics of five CYP cocktail or five transporters cocktails in two groups of randomly assigned rats. Next, a pharmacokinetic comparison was conducted between the CYP or transporter cocktail group and the dual cocktail group, respectively. None of the ten comparison groups was found to be statistically significant, indicating the CYP and transporter substrate sets or dual cocktail set could be concomitantly administered in rats. The "Dual Cocktail" was further validated by assessing the metabolism of nifedipine and omeprazole, which was significantly reduced by a single oral dose of ketoconazole (10 mg/kg); however, no changes were observed in the pharmacokinetic parameters of other probe substrates. Additionally, multiple oral doses of rifampin (20 mg/kg) reduced the plasma concentrations of nifedipine and digoxin, although not any of the other substrates. In conclusion, the dual cocktail can be used to characterize potential pharmacokinetic drug-drug interactions by simultaneously monitoring the activity of multiple CYP isoforms and transporters.

Impact of quercetin on pharmacokinetics of quetiapine: insights from in-vivo studies in wistar rats

Quercetin (QCN) is commonly used in high doses as a dietary supplement for weight loss. Psychotic patients are at greater risk of developing obesity than the general population. The present study was designed to understand the impact of QCN on the exposure of quetiapine (QTE), an anti-psychotic drug with narrow therapeutic index and brain penetrating capability. The content of QTE in rat plasma was analyzed through liquid chromatography-tandem mass spectrometry. The results showed a significant (p < 0.05) increase in exposure of QTE (peroral dosed) in the animals pre-treated with QCN as compared to the control group. All the animals pre-treated with QCN, succumbed to death within 3-5 min of intravenous dosing of QTE (1 mg/kg). The studies in rat liver S9 fraction indicated that QCN could increase the metabolic stability of QTE by inhibiting the activity of CYP enzymes. The brain to plasma ratio of QTE increased upon QCN pre-treatment (2.6 vs 7.7), which could be attributed to P-glycoprotein inhibition at the blood-brain barrier by QCN. The current set of studies indicated that serious herb-drug interaction between QCN and QTE might occur when they are co-administered. Caution is advised for concomitant use of QCN rich dietary supplements with QTE.

Herb-Drug Interaction of Red Ginseng Extract and Ginsenoside Rc with Valsartan in Rats

The purpose of this study was to investigate the herb-drug interactions involving red ginseng extract (RGE) or ginsenoside Rc with valsartan, a substrate for organic anion transporting polypeptide (OATP/Oatp) transporters. In HEK293 cells overexpressing drug transporters, the protopanaxadiol (PPD)-type ginsenosides- Rb1, Rb2, Rc, Rd, Rg3, compound K, and Rh2-inhibited human OATP1B1 and OATP1B3 transporters (IC50 values of 7.99-68.2 µM for OATP1B1; 1.36-30.8 µM for OATP1B3), suggesting the herb-drug interaction of PPD-type ginsenosides involving OATPs. Protopanaxatriol (PPT)-type ginsenosides-Re, Rg1, and Rh1-did not inhibit OATP1B1 and OATP1B3 and all ginsenosides tested didn't inhibit OCT and OAT transporters. However, in rats, neither RGE nor Rc, a potent OATP inhibitor among PPD-type ginsenoside, changed in vivo pharmacokinetics of valsartan following repeated oral administration of RGE (1.5 g/kg/day for 7 days) or repeated intravenous injection of Rc (3 mg/kg for 5 days). The lack of in vivo herb-drug interaction between orally administered RGE and valsartan could be attributed to the low plasma concentration of PPD-type ginsenosides (5.3-48.4 nM). Even high plasma concentration of Rc did not effectively alter the pharmacokinetics of valsartan because of high protein binding and the limited liver distribution of Rc. The results, in conclusion, would provide useful information for herb-drug interaction between RGE or PPD-type ginsenosides and Oatp substrate drugs.

Interactions of ginseng with therapeutic drugs

Ginseng is the most frequently used herbal medicine for immune system stimulation and as an adjuvant with prescribed drugs owing to its numerous pharmacologic activities. It is important to investigate the beneficial effects and interaction of ginseng with therapeutic drugs. This review comprehensively discusses drug metabolizing enzyme- and transporter-mediated ginseng-drug interaction by analyzing in vitro and clinical results with a focus on ginsenoside, a pharmacologically active marker of ginseng. Impact of ginseng therapy or ginseng combination therapy on diabetic patients and of ginseng interaction with antiplatelets and anticoagulants were evaluated based on ginseng origin and ginsenoside content. Daily administration of Korean red ginseng (0.5-3 g extract; dried ginseng > 60%) did not cause significant herb-drug interaction with drug metabolizing enzymes and transporters. Among various therapeutic drugs administered in combination with ginseng, adjuvant chemotherapy, comprising ginseng (1-3 g extract) and anticancer drugs, was effective for reducing cancer-related fatigue and improving the quality of life and emotional scores. Limited information regarding ginsenoside content in each ginseng product and plasma ginsenoside concentration among patients necessitates standardization of ginseng product and establishment of pharmacokinetic-pharmacodynamic correlation to further understand beneficial effects of ginseng-therapeutic drug interactions in future clinical studies.

Rhinacanthin-C Mediated Herb-Drug Interactions with Drug Transporters and Phase I Drug-Metabolizing Enzymes

Rhinacanthin-C is a major active constituent in Rhinacanthus nasutus (L.) Kurz, a plant widely used in herbal remedies. Its potential for pharmacokinetic herb-drug interaction may exist with drug transporters and drug metabolizing enzymes. This study assessed the possibility for rhinacanthin-C-mediated drug interaction by determining its inhibitory effects against major human efflux and influx drug transporters as well as various human cytochrome P450(CYP) isoforms. Rhinacanthin-C demonstrated a moderate permeability through the Caco-2 monolayers [P_{app (AP-to-BL)} = 1.26 × 10^-6 cm/s]. It significantly inhibited transport mediated by both P-glycoprotein (P-gp) (IC₅₀ = 5.20 µM) and breast cancer resistance protein (BCRP) (IC₅₀ = 0.83 µM) across Caco-2 and BCRP-overexpressing Madin-Darby canine kidney II cells (MDCKII) cells. This compound also strongly inhibited uptake mediated by organic anion-transporting polypeptide 1B1 (OATP1B1) (IC₅₀ = 0.70 µM) and OATP1B3 (IC₅₀ = 3.95 µM) in OATP1B-overexpressing HEK cells. In addition to its inhibitory effect on these drug transporters, rhinacanthin-C significantly inhibited multiple human CYP isoforms including CYP2C8 (IC₅₀ = 4.56 µM), 2C9 (IC₅₀ = 1.52 µM), 2C19 (IC₅₀ = 28.40 µM), and 3A4/5 (IC₅₀ = 53 µM for midazolam and IC₅₀ = 81.20 µM for testosterone), but not CYP1A2, 2A6, 2B6, 2D6, and 2E1. These results strongly support a high propensity for rhinacanthin-C as a perpetrator of clinical herb-drug interaction via inhibiting various influx and efflux drug transporters (i.e., P-gp, BCRP, OATP1B1, and OATP1B3) and CYP isoforms (i.e., CYP2C8, CYP2C9, and CYP2C19). Thus, the potential for significant pharmacokinetic herb-drug interaction should be addressed when herbal products containing rhinacanthin-C are to be used in conjunction with other prescription drugs.

A Danshensu-Tetramethylpyrazine Conjugate DT-010 Overcomes Multidrug Resistance in Human Breast Cancer

Background: We previously demonstrated that a Danshensu-Tetramethylpyrazine conjugate DT-010 enhanced anticancer effect of doxorubicin (Dox) in Dox-sensitive human breast cancer cells, and protected against Dox-induced cardiotoxicity. This work was designed to see whether DT-010 overcomes Dox resistance in resistant human breast cancer cells.

Methods: The effects of DT-010, Dox or their combination on cell viability of Dox-resistant human breast cancer MCF-7/ADR cells were conducted using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Apoptosis was examined by flow cytometry after Annexin V-FITC/PI co-staining. Dox accumulation in MCF-7/ADR cells was detected by flow cytometry and fluorescence microscopy. A fluorometric multidrug resistance (MDR) assay kit was used to evaluate the effect of DT-010 on MDR transporter activity. P-glycoprotein (P-gp) expression and activity were analyzed by Western blot and rhodamine 123 (Rh123) efflux assay, respectively. The effects of DT-010 on glycolysis and mitochondrial stress were detected using an Extracellular Flux Analyzer. A Succinate Dehydrogenase Activity Assay kit was used to measure mitochondrial complex II activity.

Results: At non-cytotoxic concentrations, DT-010 in combination with Dox led to a significant growth inhibition of MCF-7/ADR cells, suggesting a synergy between DT-010 and Dox to reverse Dox resistance. DT-010 restored Dox-mediated apoptosis and p53 induction in MCF-7/ADR cells. DT-010 increased Dox accumulation in MCF-7/ADR cells via inhibiting P-gp activity, but without changing P-gp expression. Further studies showed that DT-010 significantly inhibited glycolysis and mitochondrial function of MCF-7/ADR cells. Mitochondrial complex II activity was inhibited by DT-010 or DT-010/Dox combination, but not by Dox. The DT-010-mediated suppression of metabolic process may render cells more vulnerable to Dox treatment and thus result in enhanced efficacy.

Conclusions: The results indicate that DT-010 overcomes Dox resistance in human breast cancer cells through a dual action via simultaneously inhibiting P-gp-mediated drug efflux and influencing metabolic process.

Multiple circulating saponins from intravenous ShenMai inhibit OATP1Bs in vitro: potential joint precipitants of drug interactions

ShenMai, an intravenous injection prepared from steamed Panax ginseng roots (Hongshen) and Ophiopogon japonicus roots (Maidong), is used as an add-on therapy for coronary artery disease and cancer; saponins are its bioactive constituents. Since many saponins inhibit human organic anion-transporting polypeptides (OATP)1B, this investigation determined the inhibition potencies of circulating ShenMai saponins on the transporters and the joint potential of these compounds for ShenMai-drug interaction. Circulating saponins and their pharmacokinetics were characterized in rats receiving a 30-min infusion of ShenMai at 10 mL/kg. Inhibition of human OATP1B1/1B3 and rat Oatp1b2 by the individual saponins was investigated in vitro; the compounds' joint inhibition was also assessed in vitro and the data was processed using the Chou-Talalay method. Plasma protein binding was assessed by equilibrium dialysis. Altogether, 49 saponins in ShenMai were characterized and graded into: 10-100 μmol/day (compound doses from ShenMai; 7 compounds), 1-10 μmol/day (17 compounds), and <1 μmol/day (25 compounds, including Maidong ophiopogonins). After dosing, circulating saponins were protopanaxadiol-type ginsenosides Rb₁, Rb₂, Rc, Rd, Ra₁, Rg₃, Ra₂, and Ra₃, protopanaxatriol-type ginsenosides Rg₁, Re, Rg₂, and Rf, and ginsenoside Ro. The protopanaxadiol-type ginsenosides exhibited maximum plasma concentrations of 2.1-46.6 μmol/L, plasma unbound fractions of 0.4-1.0% and terminal half-lives of 15.6-28.5 h (ginsenoside Rg₃, 1.9 h), while the other ginsenosides exhibited 0.1-7.7 μmol/L, 20.8-99.2%, and 0.2-0.5 h, respectively. The protopanaxadiol-type ginsenosides, ginsenosides without any sugar attachment at C-20 (except ginsenoside Rf), and ginsenoside Ro inhibited OATP1B3 more potently (IC₅₀, 0.2-3.5 µmol/L) than the other ginsenosides (≥22.6 µmol/L). Inhibition of OATP1B1 by ginsenosides was less potent than OATP1B3 inhibition. Ginsenosides Rb₁, Rb₂, Rc, Rd, Ro, Ra₁, Re, and Rg₂ likely contribute the major part of OATP1B3-mediated ShenMai-drug interaction potential, in an additive and time-related manner.

Combination of shikonin with paclitaxel overcomes multidrug resistance in human ovarian carcinoma cells in a P-gp-independent manner through enhanced ROS generation

Background

Shikonin (SKN), a naphthoquinone compound, is isolated from Chinese herbal medicine Lithospermum root and has been studied as an anticancer drug candidate in human tumor models. This study is designed to investigate whether SKN can sensitize the therapeutic effect of paclitaxel (PTX) in drug-resistant human ovarian carcinoma cells.

Methods

Human ovarian carcinoma A2780 cell along with the paired PTX-resistant A2780/PTX cells were used. The effects of SKN, PTX or their combination on cell viability were conducted using Sulforhodamine B assay. P-glycoprotein (P-gp) expression was analyzed by flow cytometry after staining with P-gp-FITC anti-body. P-gp activity was determined by a fluorometric MDR assay kit or a rhodamine 123-based efflux assay, respectively. Apoptosis was evaluated by flow cytometry after Annexin V-FITC/PI co-staining. The effect of SKN, PTX or their combination on reactive oxygen species (ROS) generation and expression of pyruvate kinase M2 (PKM2) were investigated using flow cytometry or western blotting, respectively. PKM2 activity was detected by a Pyruvate Kinase Assay Kit.

Results

SKN/PTX co-treatment led to synergistically enhanced cytotoxicity and apoptosis in PTX-resistant ovarian cancer cells, indicating the circumvention of multidrug resistance (MDR) of PTX by SKN. Further study indicated that the MDR reversal effect of SKN was independent of inhibiting activity of the efflux transporter P-gp. Notably, SKN/PTX significantly increased the generation of intracellular ROS in A2780/PTX cells, and scavenging intracellular ROS blocked the sensitizing effects of SKN in PTX-induced cytotoxicity and apoptosis in A2780/PTX cells, but not in A2780 cells. Furthermore, SKN/PTX-induced downregulation of PKM2 (a key enzyme in glycolysis) and the suppression of its activity were inhibited by a ROS scavenger N-acetyl cysteine (NAC), suggesting that the synergy of the SKN/PTX combination may be not rely on PKM2 suppression.

Conclusions

These results reveal a P-gp-independent mechanism through ROS generation for the SKN/PTX combination to overcome MDR in ovarian cancer.

Electronic supplementary material

The online version of this article (10.1186/s13020-019-0231-3) contains supplementary material, which is available to authorized users.

Glycyrrhizin has a high likelihood to be a victim of drug-drug interactions mediated by hepatic organic anion-transporting polypeptide 1B1/1B3

BACKGROUND AND PURPOSE

Intravenous glycyrrhizin, having anti-inflammatory and hepatoprotective properties, is incorporated into the management of liver diseases in China. This investigation was designed to elucidate the molecular mechanism underlying hepatobiliary excretion of glycyrrhizin and to investigate its potential for drug-drug interactions on organic anion-transporting polypeptide (OATP)1B.

EXPERIMENTAL APPROACH

Human transporters mediating hepatobiliary excretion of glycyrrhizin were characterized at the cellular and vesicular levels and compared with rat hepatic transporters. The role of Oatp1b2 in glycyrrhizin's elimination and pharmacokinetics was evaluated in rats using the inhibitor rifampin. A physiologically based pharmacokinetic (PBPK) model for glycyrrhizin, incorporating transporter-mediated hepatobiliary excretion, was established and applied to predict potential drug-drug interactions related to glycyrrhizin in humans.

KEY RESULTS

Hepatobiliary excretion of glycyrrhizin involved human OATP1B1/1B3 (Oatp1b2 in rats)-mediated hepatic uptake from blood and human multidrug resistance-associated protein (MRP)2/breast cancer resistance protein (ABCP)/bile salt export pump (BSEP)/multidrug resistance protein 1 (Mrp2/Abcp/Bsep in rats)-mediated hepatic efflux into bile. In rats, rifampin impaired hepatic uptake of glycyrrhizin significantly increasing its systemic exposure. Glomerular-filtration-based renal excretion of glycyrrhizin was slow due to extensive protein binding in plasma. Quantitative analysis using the PBPK model demonstrated that OATP1B1/1B3 have critical roles in the pharmacokinetics of glycyrrhizin, which is highly likely to be a victim of drug-drug interactions when co-administered with potent dual inhibitors of these transporters.

CONCLUSIONS AND IMPLICATIONS

Transporter-mediated hepatobiliary excretion governs glycyrrhizin's elimination and pharmacokinetics. Understanding glycyrrhizin's potential drug-drug interactions on OATP1B1/1B3 should enhance the therapeutic outcome of glycyrrhizin-containing drug combinations on liver diseases.

Transporter-mediated natural product-drug interactions for the treatment of cardiovascular diseases

The growing use of natural products in cardiovascular (CV) patients has been greatly raising the concerns about potential natural product–CV drug interactions. Some of these may lead to unexpected cardiovascular adverse effects and it is, therefore, essential to identify or predict potential natural product–CV drug interactions, and to understand the underlying mechanisms. Drug transporters are important determinants for the pharmacokinetics of drugs and alterations of drug transport has been recognized as one of the major causes of natural product–drug interactions. In last two decades, many CV drugs (e.g., angiotensin II receptor blockers, beta-blockers and statins) have been identified to be substrates and inhibitors of the solute carrier (SLC) transporters and the ATP-binding cassette (ABC) transporters, which are two major transporter superfamilies. Meanwhile, in vitro and in vivo studies indicate that a growing number of natural products showed cardioprotective effects (e.g., gingko biloba, danshen and their active ingredients) are also substrates and inhibitors of drug transporters. Thus, to understand transporter-mediated natural product–CV drug interactions is important and some transporter-mediated interactions have already shown to have clinical relevance. In this review, we review the current knowledge on the role of ABC and SLC transporters in CV therapy, as well as transporter modulation by natural products used in CV diseases and their induced natural product–CV drug interactions through alterations of drug transport. We hope our review will aid in a comprehensive summary of transporter-mediated natural product–CV drug interactions and help public and physicians understand these type of interactions.

Apigenin, a novel candidate involving herb-drug interaction (HDI), interacts with organic anion transporter 1 (OAT1)

BACKGROUND

Apigenin is a flavonoid compound, widely distributed in natural plants. Various studies have suggested that apigenin has inhibitory effects towards several drug transporters, such as the organic anion transporting (OAT) polypeptides, 1B1 and 1B3 (OATP1B1 and OATP1B3). However, the mechanism by which apigenin interacts with OAT1 has not been well studied.

METHODS

MDCK cells stably-expressing OAT1 were used to examine the inhibitory effects of apigenin on OAT1. UPLC-MS/MS was used to evaluate the in vitro and in vivo effects of apigenin on the uptake of acyclovir by OAT1. Cytotoxicity was determined by the cell viability, MTT assays.

RESULTS

Apigenin effectively inhibited the activity of OAT1 in a dose-dependent manner with an IC50 value of 0.737μM. Pre-incubation of cells with apigenin caused a time-dependent inhibition (TDI) of OAT1. Additionally, we examined the interactions between apigenin and acyclovir or adefovir. Data showed that apigenin (1μM) significantly blocked the uptake of acyclovir by OAT1 in vitro with an inhibition rate of 55%. In vivo, apigenin could increase the concentration of acyclovir in plasma when co-administered with acyclovir. Importantly, the MTT assays showed that, at a dose of 50μM, apigenin significantly reduced the cytotoxicity of adefovir and substantially increased cell viability from 50.6% to 112.62%.

CONCLUSION

Our results demonstrate that apigenin regulates OAT1, and can cause TDI or herb-drug interaction (HDI) when used in combination with acyclovir or adefovir. Therefore, apigenin could be used as a nephroprotective agent when used in combination with the substrates of OAT1.

Mechanism Underlying the Reversal of Drug Resistance in P-Glycoprotein-Expressing Leukemia Cells by Pinoresinol and the Study of a Derivative

P-glycoprotein (P-gp) is a membrane protein associated with multidrug resistance (MDR) due to its key role in mediating the traffic of chemotherapeutic drugs outside cancer cells, leading to a cellular response that hinders efforts toward successful therapy. With the aim of finding agents that circumvent the MDR phenotype mediated by P-gp, 15 compounds isolated from native and naturalized plants of Argentina were screened. Among these, the non-cytotoxic lignan (±) pinoresinol successfully restored sensitivity to doxorubicin from 7 μM in the P-gp overexpressed human myelogenous leukemia cells, Lucena 1. This resistance-reversing effect was confirmed by competitively increasing the intracellular doxorubicin accumulation and by significantly inhibiting the efflux of doxorubicin and, to a lesser extent, that of rhodamine 123. The activity obtained was similar to that observed with verapamil. No such results were observed in the sensitive parental K562 cell line. To gain deeper insight into the mode of action of pinoresinol, its effect on P-gp function and expression was examined. The docking simulations indicated that the lignan bound to P-gp at the apex of the V-shaped transmembrane cavity, involving transmembrane helices 4, 5, and 6, and partially overlapped the binding region of tariquidar, which was used as a positive control. These results would shed some light on the nature of its interaction with P-gp at molecular level and merit further mechanistic and kinetic studies. In addition, it showed a maximum 29% activation of ATP hydrolysis and antagonized verapamil-stimulated ATPase activity with an IC₅₀ of 20.9 μM. On the other hand, pinoresinol decreased the presence of P-gp in the cell surface. Derivatives of pinoresinol with improved activity were identified by docking studies. The most promising one, the non-cytotoxic 1-acetoxypinoresinol, caused a reversion of doxorubicin resistance from 0.11 μM and thus higher activity than the lead compound. It also caused a significant increase in doxorubicin accumulation. Results were similar to those observed with verapamil. The results obtained positioned these compounds as potential candidates for effective agents to overcome P-gp-mediated MDR, leading to better outcomes for leukemia chemotherapy.

Herb-Drug Interactions of Commonly Used Chinese Medicinal Herbs

With more and more popular use of traditional herbal medicines, in particular Chinese herbal medicines, herb-drug interactions have become a more and more important safety issue in the clinical applications of the conventional drugs. Researches in this area are increasing very rapidly. Herb-drug interactions are complicated due to the fact that multiple chemical components are involved, and these compounds may possess diverse pharmacological activities. Interactions can be in both pharmacokinetics and pharmacodynamics. Abundant studies focused on pharmacokinetic interactions of herbs and drugs. Herbs may affect the behavior of the concomitantly used drugs by changing their absorption, distribution, metabolism, and excretion. Studies on pharmacodynamics interactions of herbs and drugs are still very limited. Herb-drug interactions are potentially causing changes in drug levels and drug activities and leading to either therapeutic failure or toxicities. Sometime it can be fatal. The exposures to drugs, lacking of knowledge in the potential adverse herb-drug interactions, will put big risk to patients' safety in medical services. On the contrary, some interactions may be therapeutically beneficial. It may be used to help develop new therapeutic strategies in the future. This chapter is trying to review the development in the area of herb-drug interactions based on the recently published research findings. Information on the potential interactions among the commonly used Chinese medicinal herbs and conventional drugs is summarized in this chapter.

Salvia miltiorrhiza Roots against Cardiovascular Disease: Consideration of Herb-Drug Interactions

Salvia miltiorrhiza root (Danshen) is widely used in Asia for its cardiovascular benefits and contains both hydrophilic phenolic acids and lipophilic tanshinones, which are believed to be responsible for its therapeutic efficacy. This review summarized the effects of these bioactive components from S. miltiorrhiza roots on pharmacokinetics of comedicated drugs with mechanic insights regarding alterations of protein binding, enzyme activity, and transporter activity based on the published data stemming from both in vitro and in vivo human studies. In vitro studies indicated that cytochrome P450 (CYP450), carboxylesterase enzyme, catechol-O-methyltransferase, organic anion transporter 1 (OAT1) and OAT3, and P-glycoprotein were the major targets involved in S. miltiorrhiza-drug interactions. Lipophilic tanshinones had much more potent inhibitory effects towards CYPs activities compared to hydrophilic phenolic acids, evidenced by much lower K_i values of the former. Clinical S. miltiorrhiza-drug interaction studies were mainly conducted using CYP1A2 and CYP3A4 probe substrates. In addition, the effects of coexisting components on the pharmacokinetic behaviors of those noted bioactive compounds were also included herein.