Quercetin-3-rhamnoglucoside (rutin) stimulates transport of organic anion compounds mediated by organic anion transporting polypeptide 2B1

Intestinal absorption mechanism and nutritional synergy promotion strategy of dietary flavonoids: transintestinal epithelial pathway mediated by intestinal transport proteins

Dietary flavonoids exhibit a variety of physiological functions in regulating glucose and lipid metabolism, improving cardiovascular function, and enhancing stress resistance. However, poor intestinal absorption limits their health benefits. Previous studies on improving the absorption efficiency of flavonoids have focused on targeted release, enhanced gastrointestinal stability and prolonged retention time in digestive tract. But less attention has been paid to promoting the uptake and transport of flavonoids by intestinal epithelial cells through modulation of transporter protein-mediated pathways. Interestingly, some dietary nutrients have been found to modulate the expression or function of transporter proteins, thereby synergistically or antagonistically affecting flavonoid absorption. Therefore, this paper proposed an innovative regulatory strategy known as the "intestinal transport protein-mediated pathway" to promote intestinal absorption of dietary flavonoids. The flavonoid absorption mechanism in the intestinal epithelium, mediated by intestinal transport proteins, was summarized. The functional differences between the uptake transporter and efflux transporters during flavonoid trans-intestinal cellular transport were discussed. Finally, from the perspective of nutritional synergy promotion of absorption, the feasibility of promoting flavonoid intestinal absorption by regulating the expression/function of transport proteins through dietary nutrients was emphasized. This review provides a new perspective and developing precise dietary nutrient combinations for efficient dietary flavonoid absorption.

Potential Herb-Drug Interactions in the Management of Age-Related Cognitive Dysfunction

Late-life mild cognitive impairment and dementia represent a significant burden on healthcare systems and a unique challenge to medicine due to the currently limited treatment options. Plant phytochemicals have been considered in alternative, or complementary, prevention and treatment strategies. Herbals are consumed as such, or as food supplements, whose consumption has recently increased. However, these products are not exempt from adverse effects and pharmacological interactions, presenting a special risk in aged, polymedicated individuals. Understanding pharmacokinetic and pharmacodynamic interactions is warranted to avoid undesirable adverse drug reactions, which may result in unwanted side-effects or therapeutic failure. The present study reviews the potential interactions between selected bioactive compounds (170) used by seniors for cognitive enhancement and representative drugs of 10 pharmacotherapeutic classes commonly prescribed to the middle-aged adults, often multimorbid and polymedicated, to anticipate and prevent risks arising from their co-administration. A literature review was conducted to identify mutual targets affected (inhibition/induction/substrate), the frequency of which was taken as a measure of potential interaction. Although a limited number of drugs were studied, from this work, interaction with other drugs affecting the same targets may be anticipated and prevented, constituting a valuable tool for healthcare professionals in clinical practice.

The involvement of human organic anion transporting polypeptides (OATPs) in drug-herb/food interactions

Organic anion transporting polypeptides (OATPs) are important transporter proteins that are expressed at the plasma membrane of cells, where they mediate the influx of endogenous and exogenous substances including hormones, natural compounds and many clinically important drugs. OATP1A2, OATP2B1, OATP1B1 and OATP1B3 are the most important OATP isoforms and influence the pharmacokinetic performance of drugs. These OATPs are highly expressed in the kidney, intestine and liver, where they determine the distribution of drugs to these tissues. Herbal medicines are increasingly popular for their potential health benefits. Humans are also exposed to many natural compounds in fruits, vegetables and other food sources. In consequence, the consumption of herbal medicines or food sources together with a range of important drugs can result in drug-herb/food interactions via competing specific OATPs. Such interactions may lead to adverse clinical outcomes and unexpected toxicities of drug therapies. This review summarises the drug-herb/food interactions of drugs and chemicals that are present in herbal medicines and/or food in relation to human OATPs. This information can contribute to improving clinical outcomes and avoiding unexpected toxicities of drug therapies in patients.

Differential interactions of carbamate pesticides with drug transporters

Pesticides are now recognised to interact with drug transporters, but only few data are available on this issue for carbamate pesticides, a widely used class of agrochemicals, to which humans are highly exposed. The present study was therefore designed to determine whether four representative carbamate pesticides, i.e. the insecticides aminocarb and carbofuran, the herbicide chlorpropham and the fungicide propamocarb, may impair activities of main drug transporters implicated in pharmacokinetics. The interactions of carbamates with solute carrier and ATP-binding cassette transporters were investigated using cultured transporter-overexpressing cells, reference substrates and spectrofluorimetry-, liquid chomatography/tandem mass spectrometry- or radioactivity-based methods. Aminocarb and carbofuran exerted no or minimal effects on transporter activities, whereas chlorpropham inhibited BCRP and OAT3 activities and propamocarb decreased those of OCT1 and OCT2, but cis-stimulated that of MATE2-K. Such alterations of transporters however required chlorpropham/propamocarb concentrations in the 5-50 µM range, likely not relevant to environmental exposure. Trans-stimulation assays and propamocarb accumulation experiments additionally suggested that propamocarb is not a substrate for OCT1, OCT2 and MATE2-K. These data indicate that some carbamate pesticides can interact in vitro with some drug transporters, but only when used at concentrations higher than those expected to occur in environmentally exposed humans.

Investigation of Fluorescent Substrates and Substrate-Dependent Interactions of a Drug Transporter Organic Anion Transporting Polypeptide 2B1 (OATP2B1)

PURPOSE

In this study, we investigated organic anion transporting polypeptide 2B1 (OATP2B1)-mediated uptake of fluorescent anions to better identify fluorescent substrates for in vitro OATP2B1 assays. The OATP2B1 is involved in the intestinal absorption and one of the pharmacokinetic determinants of orally administered drugs.

METHODS

A microplate reader was used to determine the cellular accumulation of the fluorescent compounds into the OATP2B1 or the empty vector-transfected HEK293 cells.

RESULTS

Two types of derivatives were found to be OATP2B1 substrates: heavy halogenated derivatives, such as 4',5'-dibromofluorescein (DBF), and carboxylated derivatives, such as 5-carboxyfluorescein (5-CF). The DBF and 5-CF were transported in a time and concentration-dependent manner. The DBF was transported at a broad pH (pH 6.5-8.0) while 5-CF was transported at an acidic pH (pH 5.5-6.5). The K_m values were 0.818 ± 0.067 μM at pH 7.4 for DBF and 8.56 ± 0.41 μM at pH 5.5 for 5-CF. The OATP2B1 inhibitors, including atorvastatin, bromosulfophthalein, glibenclamide, sulfasalazine, talinolol, and estrone 3-sulfate, inhibited the DBF and the 5-CF transport. Contrastively, testosterone, dehydroepiandrosterone sulfate, and progesterone inhibited the DBF transport but stimulated the 5-CF transport. Natural flavonoid aglycones, such as naringenin and baicalein, also exhibited substrate-dependent effects in this manner.

CONCLUSION

We found two fluorescein analogs, DBF and 5-CF as the OATP2B1 substrates that exhibited substrate-dependent interactions.

Stimulatory effect on the transport mediated by organic anion transporting polypeptide 2B1

Drug-drug interaction (DDI) is one of causes of adverse drug events and can result in life-threatening consequences. Organic anion-transporting polypeptide (OATP) 2B1 is a major uptake transporter in the intestine and contributes to transport various clinically used therapeutic agents. The intestine has a high risk of DDI, because it has a special propensity to be exposed to a high concentration of drugs. Thus, understanding drug interaction mediated by OATP2B1 in the absorption process is important for the prevention of adverse drug events, including decrease in the therapeutic effect of co-administered drugs. Acute drug interaction occurs through the direct inhibitory effect on transporters, including OATP2B1. Moreover, some compounds such as clinically used drugs and food components have an acute stimulatory effect on transport of co-administered drugs by OATP2B1. This review summarizes the acute stimulatory effect on the transport mediated by OATP2B1 and discusses the mechanisms of the acute stimulatory effects of compounds. There are two types of acute stimulatory effects, substrate-independent and -dependent interactions on OATP2B1 function. The facilitating translocation of OATP2B1 to the plasma membrane is one of causes for the substrate-independent acute stimulatory effect. On the contrary, the substrate-dependent effect is based on the direct binding to the substrate-binding site or allosteric progesterone-binding site of OATP2B1.

Black tea extract and theaflavin derivatives affect the pharmacokinetics of rosuvastatin by modulating organic anion transporting polypeptide (OATP) 2B1 activity

Theaflavins (TFs) are derived from black tea, an important source of dietary polyphenols. Although the potential interactions between dietary polyphenols and drugs have been demonstrated through in vitro and in vivo studies, little information is available concerning the influence of TFs on drug disposition. Organic anion transporting polypeptide 2B1 (OATP2B1) is expressed in human enterocytes and plays a role in the intestinal absorption of numerous drugs. The current study evaluated the effects of black tea extracts on the pharmacokinetics of rosuvastatin in rats, and investigated the effect of four major TFs (theaflavin, theaflavin-3-gallate, theaflavin-3'-gallate and theaflavin-3,3'-digallate) on the transport activity of OATP2B1. Black tea extracts significantly decreased the maximum plasma concentration (C_max ) and area under the plasma concentration-time curve (AUC₀ -₈ ) of rosuvastatin by 48% and 37%, respectively (p < 0.001 and p < 0.01, respectively). Moreover, OATP2B1-mediated rosuvastatin and estrone-3-sulfate uptake was significantly reduced in the presence of TFs. A kinetic study revealed that the uptake efficiency (in terms of V_max /K_m ) of rosuvastatin was decreased following treatment with TFs. Black tea extracts also reduced OATP2B1-mediated rosuvastatin uptake. These results suggest that black tea reduces the plasma concentrations of rosuvastatin by inhibiting the intestinal OATP2B1-mediated transport of rosuvastatin.

Uremic solutes modulate hepatic bile acid handling and induce mitochondrial toxicity

Chronic kidney disease (CKD) is accompanied by accumulating levels of uremic solutes in the circulation. Changes in the size and composition of the bile acid pool have also been observed. We investigated via which mechanisms uremic solutes may interfere with hepatocyte function and thus contribute to altered bile acid handling. We studied interference on the level of bile acid synthesis by cytochrome P450 7A1 (CYP7A1), explored effects on hepatic bile acid transporters, and investigated effects on mitochondrial function. In HEK293 cells overexpressing bile salt transporters, we observed that p-cresyl sulfate inhibited Na⁺-taurocholate cotransporting polypeptide (NTCP)-mediated uptake of taurocholic acid (TCA), whereas organic anion-transporting polypeptide 1B1 (OATP1B1)-mediated TCA uptake was increased. Assays in transporter-overexpressing membrane vesicles revealed that kynurenic acid inhibited TCA transport via the bile salt efflux pump (BSEP), whereas p-cresyl glucuronide and hippuric acid increased TCA efflux via multidrug resistance-associated protein 3 (MRP3). Moreover, indoxyl sulfate decreased mRNA expression of NTCP, OATP1B3 and CYP7A1 in primary human hepatocytes. Transport studies confirmed a decreased TCA uptake in indoxyl sulfate-exposed hepatocytes. Decreased hepatocyte viability was found for all seven uremic solutes tested, whereas five out of seven also decreased intracellular ATP levels and mitochondrial membrane potential. In conclusion, uremic solutes affect hepatic bile acid transport and mitochondrial function. This can contribute to the altered bile acid homeostasis observed in CKD patients.

Interactions between crude drug extracts used in Japanese traditional Kampo medicines and organic anion-transporting polypeptide 2B1

ETHNOPHARMACOLOGICAL RELEVANCE

The use of herbal medicines has become popular worldwide, and the information on drug interactions between herbal medicines and chemical drugs is needed.

AIM OF THE STUDY

We screened the inhibitory effects of crude drugs used in Kampo medicines used in Japan on organic anion-transporting polypeptide (OATP) 2B1 to predict potential interactions between Kampo medicines and chemical drugs used together.

MATERIALS AND METHODS

We chose 98 kinds of crude drugs frequently used as ingredients of Kampo formulations in Japan and prepared their boiling water extracts. We then screened their inhibitory effects on OATP2B1 by measuring the uptake of estrone 3-sulphate (E3S) by HEK293 cells stably expressing OATP2B1.

RESULTS

At the concentration of 100µg/ml, the extracts prepared from 12 kinds of crude drugs, Scuteralliae Radix, Arecae Semen, Aurantii Fructus Immaturus, Perillae Herba, Panacis Japonici Rhizoma, Moutan Cortex, Polygalae Radix, Rhei Rhizoma, Cannabis Fructus, Chrysanthemi Flos, Eriobotryae Folium, and Querci Cortex, suppressed the function of OATP2B1 by less than 20%. The extract of bofutsushosan, a representative Kampo formulation, inhibited OATP2B1 function with sufficient levels to suppress absorption of OATP2B1 substrates in clinics. We further evaluated the inhibitory effects of several ingredients containing Rhei Rhizoma, Perillae Herba, and Moutan Cortex on OATP2B1.

CONCLUSIONS

Because of crude drugs used in Kampo medicines might suppress absorption of OATP2B1 substrates, these results may contribute to the safe and effective use of Kampo medicine in clinics. A list of abbreviations: EC, (-)-epicatechin; ECG, epicatechin gallate; EGC, epigallocatechin; EGCG, Epigallocatechin gallate; FBS, fetal bovine serum; grapefruit juice; HEK293, Human embryonic kidney; IC_50, The half inhibitory concentration; OATP, organic anion-transporting polypeptide; β-PGG, penta-O-galloyl-β-D-glucose; t.i.d, 3 times a day.

Interactions of crizotinib and gefitinib with organic anion-transporting polypeptides (OATP)1B1, OATP1B3 and OATP2B1: gefitinib shows contradictory interaction with OATP1B3

1. The drug-drug interaction (DDI) mediated by organic anion-transporting polypeptide (OATP)1B1, OATP1B3 and OATP2B1 has a major impact on the hepatic clearance of drugs. The effects of tyrosine kinase inhibitors (TKIs) on OATPs have not been well studied. In the present study, we evaluated the contribution of OATPs to the hepatic uptake of crizotinib and gefitinib and the interaction of those TKIs with OATPs to estimate DDIs. 2. To clarify whether crizotinib and gefitinib were substrates for OATPs, we performed uptake studies. We examined the effects of the TKIs on uptake of typical substrates and fluvastatin via OATPs. IC₅₀ and EC₅₀ values of the TKIs were calculated. 3. OATP1B3- and OATP2B1-mediated crizotinib uptake and OATP2B1-mediated gefitinib uptake were observed. Gefitinib accelerated OATP1B3-mediated [³H]TCA uptake and inhibited OATP2B1-mediated [³H]E₃S uptake. On the other hand, gefitinib inhibited OATP1B1- and OATP2B1-mediated fluvastatin uptake. 4. We provided basic information to estimate the DDI on OATPs caused by TKIs. The DDI on OATPs caused by gefitinib could occur in a normal clinical situation. And the uptake of crizotinib into the intrahepatocellular environment via OATPs may induce DDI and liver damage. We therefore emphasize the necessity of careful use of TKIs.

Co-administration of paroxetine increased the systemic exposure of pravastatin in diabetic rats due to the decrease in liver distribution

1. Liver distribution and systemic exposure of pravastatin were the determinant factors of efficacy and toxicity of pravastatin. Aim of the present study was to investigate the effect of paroxetine on the liver distribution and systemic exposure of pravastatin in diabetic rats induced by combining high fat diet (HFD) and low-dose streptozotocin (STZ). 2. Plasma concentrations and liver distribution of pravastatin were measured in the presence of paroxetine. Effect of paroxetine on pravastatin excretion via bile, intestine, feces and urine, as well as pravastatin absorption via intestine was documented. Freshly isolated hepatocytes and Caco-2 cells were used to investigate the effect of paroxetine on pravastatin transport. 3. Paroxetine increased the systemic exposure of pravastatin and decreased hepatic distribution of pravastatin in diabetic rats. In vitro, paroxetine inhibited the hepatic uptake of pravastatin and promoted the efflux of pravastatin in freshly isolated hepatocytes, which may partly explain the decreased hepatic distribution of pravastatin by paroxetine. It was also observed that paroxetine promoted the absorption of pravastatin via jejunum and the uptake of pravastatin in Caco-2 cells. 4. We concluded that paroxetine increased the systemic exposure of pravastatin partly via promoting absorption via jejunum and inhibiting hepatic uptake of pravastatin.

Identification of natural products as modulators of OATP2B1 using LC-MS/MS to quantify OATP-mediated uptake

CONTEXT

Organic anion-transporting polypeptide 2B1 (OATP2B1) which is highly expressed in enterocytes and hepatocytes could be a key determinant for the intestinal absorption and hepatic uptake of its substrate drugs. Natural products are commonly used in traditional Chinese medicine, foods, and beverages.

OBJECTIVE

The objective of this study is to determine the OATP2B1-mediated drug interactions that could occur between natural products and OATP2B1 substrate drugs.

MATERIALS AND METHODS

Human OATP2B1 was transiently expressed in human embryonic kidney (HEK293) cells and characterized by immunofluorescence, Western blot, and uptake assay. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods for detecting OATP2B1 substrates estrone-3-sulfate (E3S) and three statins had been developed and were employed to investigate the effects of 27 frequently used natural products on the function of OATP2B1. Uptake of 5 μM E3S and 1 μM statins in the absence or presence of natural products was measured at 37 °C for 2 min with empty vector- and OATP2B1-transfected HEK293 cells. The IC50 values of inhibitors for OATP2B1-mediated 5 μM E3S uptake were determined.

RESULTS

Our results showed that mulberrin, scutellarin, quercetin, and glycyrrhetinic acid were strong inhibitors of OATP2B1-mediate E3S uptake with IC50 values being 1.8, 2.0, 7.5, and 13.0 μM, which were comparable with their plasma concentrations in clinical trials. They also inhibited OATP-mediated uptake of atorvastatin, fluvastatin, and rosuvastatin. These results indicated that clinically relevant drug interactions could occur between these natural compounds and OATP2B1 substrate drugs.

DISCUSSION AND CONCLUSION

The information obtained from this study might be helpful to predict and to avoid potential OATP2B1-mediated drug interactions.