The 2-aminoethyl diphenylborinate-based fluorescent method identifies quercetin and luteolin metabolites as substrates of Organic anion transporting polypeptides, OATP1B1 and OATP2B1.

Organic anion transporting polypeptides (OATPs), OATP1B1 and OATP2B1 are membrane proteins mediating the cellular uptake of chemically diverse organic compounds. OATP1B1 is exclusively expressed in hepatocytes and plays a key role in hepatic detoxification. The ubiquitously expressed OATP2B1 promotes the intestinal absorption of orally administered drugs.

Interaction of mycotoxins zearalenone, α-zearalenol, and β-zearalenol with cytochrome P450 (CYP1A2, 2C9, 2C19, 2D6, and 3A4) enzymes and organic anion transporting polypeptides (OATP1A2, OATP1B1, OATP1B3, and OATP2B1).

Zearalenone (ZEN) is a mycoestrogen produced by Fusarium fungi. ZEN is a frequent contaminant in cereal-based products, representing significant health threat. The major reduced metabolites of ZEN are α-zearalenol (α-ZEL) and β-zearalenol (β-ZEL).

The fluorescence-based competitive counterflow assay developed for organic anion transporting polypeptides 1A2, 1B1, 1B3 and 2B1 identifies pentamidine as a selective OATP1A2 substrate.

Organic anion transporting polypeptides OATP1A2, OATP1B1, OATP1B3 and OATP2B1 are Na - and ATP-independent exchangers of large, organic compounds, encompassing structurally diverse xenobiotics, including various drugs. These OATPs influence intestinal absorption (OATP2B1), hepatic clearance (OATP1B1/3) and blood to brain penetration (OATP1A2, OATP2B1) of their drug substrates. Consequently, OATP-mediated drug or food interactions may lead to altered pharmacokinetics and toxicity.

Interactions of the Anti-SARS-CoV-2 Agents Molnupiravir and Nirmatrelvir/Paxlovid with Human Drug Transporters.

Orally administered small molecules may have important therapeutic potential in treating COVID-19 disease. The recently developed antiviral agents, Molnupiravir and Nirmatrelvir, have been reported to be efficient treatments, with only moderate side effects, especially when applied in the early phases of this disease. However, drug-drug and drug-transporter interactions have already been noted by the drug development companies and in the application notes.

Synthesis and photodynamic activity of aza-BODIPY-based photosensitizers.

Aza-BODIPY dyes have recently come to attention owing to their excellent chemical and photophysical properties. In particular, their absorption and emission maxima can efficiently be shifted to the red or even to the NIR spectral region. On this basis, aza-BODIPY derivatives are widely investigated as fluorescent probes or phototherapeutic agents.

Organic Anion Transporting Polypeptide 3A1 (OATP3A1)-Gated Bio-Orthogonal Labeling of Intracellular Proteins.

Organic anion transporting polypeptides (OATPs) were found to readily deliver membrane impermeable, tetrazine bearing fluorescent probes into cells. This feature was explored in OATP3A1 conditioned bio-orthogonal labeling schemes of various intracellular proteins in live cells. Confocal microscopy and super-resolution microscopy (STED) studies have shown that highly specific and efficient staining of the selected intracellular proteins can be achieved with the otherwise non-permeable probes when OATP3A1 is present in the cell membrane of cells.

Fluorescence-based methods for studying activity and drug-drug interactions of hepatic solute carrier and ATP binding cassette proteins involved in ADME-Tox.

In humans, approximately 70% of drugs are eliminated through the liver. This process is governed by the concerted action of membrane transporters and metabolic enzymes. Transporters mediating hepatocellular uptake of drugs belong to the SLC (Solute carrier) superfamily of transporters.

Interaction of luteolin, naringenin, and their sulfate and glucuronide conjugates with human serum albumin, cytochrome P450 (CYP2C9, CYP2C19, and CYP3A4) enzymes and organic anion transporting polypeptide (OATP1B1 and OATP2B1) transporters.

Luteolin and naringenin are flavonoids found in various foods/beverages and present in certain dietary supplements. After a high intake of these flavonoids, their sulfate and glucuronide conjugates reach micromolar concentrations in the bloodstream. Some pharmacokinetic interactions of luteolin and naringenin have been investigated in previous studies; however, only limited data are available in regard to their metabolites.

Cloning and characterization of a novel functional organic anion transporting polypeptide 3A1 isoform highly expressed in the human brain and testis.

Organic anion transporting polypeptide 3A1 (OATP3A1, encoded by the gene) is a prostaglandin, oligopeptide, and steroid/thyroid hormone transporter with wide tissue distribution, expressed, e.g., in the human brain and testis.

Interactions of anti-COVID-19 drug candidates with hepatic transporters may cause liver toxicity and affect pharmacokinetics.

Transporters in the human liver play a major role in the clearance of endo- and xenobiotics. Apical (canalicular) transporters extrude compounds to the bile, while basolateral hepatocyte transporters promote the uptake of, or expel, various compounds from/into the venous blood stream. In the present work we have examined the in vitro interactions of some key repurposed drugs advocated to treat COVID-19 (lopinavir, ritonavir, ivermectin, remdesivir and favipiravir), with the key drug transporters of hepatocytes.

Selective antiproliferative effect of C-2 halogenated 13α-estrones on cells expressing Organic anion-transporting polypeptide 2B1 (OATP2B1).

Organic anion-transporting polypeptide 2B1 (OATP2B1) is a multispecific transporter mediating the cellular uptake of steroids and numerous drugs. OATP2B1 is abundantly expressed in the intestine and is also present in various tumors. Increased steroid hormone uptake by OATP2B1 has been suggested to promote progression of hormone dependent tumors.

8-acetoxy-trisulfopyrene as the first activatable fluorogenic probe for add-and-read assessment of Organic anion-transporting polypeptides, OATP1B1, OATP1B3, and OATP2B1.

Organic anion-transporting polypeptides, OATP1B1, OATP1B3, and OATP2B1 are multispecific membrane proteins mediating the hepatocellular uptake of structurally diverse endo- and exogenous compounds, including various kinds of drugs. Co-administration of OATP1B/2B1 substrates may lead to altered pharmacokinetics or even toxicity. Therefore, the study of the interaction with these OATPs is essential in drug development and is recommended by international regulatory agencies, the FDA, EMA, and PMDA.

Interactions of Potential Anti-COVID-19 Compounds with Multispecific ABC and OATP Drug Transporters.

During the COVID-19 pandemic, several repurposed drugs have been proposed to alleviate the major health effects of the disease. These drugs are often applied with analgesics or non-steroid anti-inflammatory compounds, and co-morbid patients may also be treated with anticancer, cholesterol-lowering, or antidiabetic agents. Since drug ADME-tox properties may be significantly affected by multispecific transporters, in this study, we examined the interactions of the repurposed drugs with the key human multidrug transporters present in the major tissue barriers and strongly affecting the pharmacokinetics.

Creation of the first monoclonal antibody recognizing an extracellular epitope of hABCC6.

Mutations in the ABCC6 gene result in calcification diseases such as pseudoxanthoma elasticum or Generalized Arterial Calcification of Infancy. Generation of antibodies recognizing an extracellular (EC) epitope of ABCC6 has been hampered by the short EC segments of the protein. To overcome this limitation, we immunized bovine FcRn transgenic mice exhibiting an augmented humoral immune response with Human Embryonic Kidney 293 cells cells expressing human ABCC6 (hABCC6).

Synergistic transport of a fluorescent coumarin probe marks coumarins as pharmacological modulators of Organic anion-transporting polypeptide, OATP3A1.

Organic anion-transporting polypeptide 3A1 (OATP3A1) is a membrane transporter mediating the cellular uptake of various hormones such as estrone-3-sulfate, prostaglandins E1 and E2 and thyroxine. OATP3A1 is widely expressed in the human body and its presence in tissue-blood barriers, neurons and muscle cells marks it as a potential pharmacological target. Herein we demonstrate that an otherwise membrane impermeant, zwitterionic fluorescent coumarin probe, bearing a sulfonate function is a potent substrate of human OATP3A1, thus readily transported into HEK-293-OATP3A1 cells allowing functional investigation and the screen of drug interactions of the OATP3A1 transporter.

Interplay of drug transporters P-glycoprotein (MDR1), MRP1, OATP1A2 and OATP1B3 in passage of maraviroc across human placenta.

Special attention is required when pharmacological treatment is indicated for a pregnant woman. P-glycoprotein (MDR1) is a well-known transporter localized in the maternal blood-facing apical membrane of placental syncytiotrophoblast and is considered to play an important role in protecting the developing fetus. Maraviroc, a MDR1 substrate that is registered for treatment of HIV infection, shows a low toxicity profile, suggesting favorable tolerability also if administered to pregnant women.

Effects of Chrysin and Its Major Conjugated Metabolites Chrysin-7-Sulfate and Chrysin-7-Glucuronide on Cytochrome P450 Enzymes and on OATP, P-gp, BCRP, and MRP2 Transporters.

Chrysin is an abundant flavonoid in nature, and it is also contained by several dietary supplements. Chrysin is highly biotransformed in the body, during which conjugated metabolites chrysin-7-sulfate and chrysin-7-glucuronide are formed. These conjugates appear at considerably higher concentrations in the circulation than the parent compound.

Fluorescent probes for the dual investigation of MRP2 and OATP1B1 function and drug interactions.

Detoxification in hepatocytes is a strictly controlled process, in which the governed action of membrane transporters involved in the uptake and efflux of potentially dangerous molecules has a crucial role. Major transporters of hepatic clearance belong to the ABC (ATP Binding Cassette) and Solute Carrier (SLC) protein families. Organic anion-transporting polypeptide OATP1B1 (encoded by the SLCO1B1 gene) is exclusively expressed in the sinusoidal membrane of hepatocytes, where it mediates the cellular uptake of bile acids, bilirubin, and also that of various drugs.

A novel fluorescence-based functional assay for human OATP1A2 and OATP1C1 identifies interaction between third-generation P-gp inhibitors and OATP1A2.

Organic anion-transporting polypeptide 1A2 (OATP1A2), expressed in the human blood-brain barrier, promotes drug uptake from the blood and hence can be exploited for central nervous system-targeted drug delivery. The thyroid transporter OATP1C1, expressed in the choroid plexus and in astrocytes, is also a potential pharmacological target. Based on their established pharmacological relevance, screening the drug interaction profile of OATP1A2 and OATP1C1 is highly desirable.

Identification of novel cell-impermeant fluorescent substrates for testing the function and drug interaction of Organic Anion-Transporting Polypeptides, OATP1B1/1B3 and 2B1.

Organic Anion-Transporting Polypeptides are multispecific membrane proteins that regulate the passage of crucial endobiotics and drugs across pharmacological barriers. OATP1B1 and OATP1B3 have been described to play a major role in the hepatic uptake of statins, antivirals and various chemotherapeutics; whereas the pharmacological role of the ubiquitously expressed OATP2B1 is less well characterized. According to current industry standards, in vitro testing for susceptibility to OATP1B1 and 1B3 mediated transport is recommended for drug candidates that are eliminated in part via the liver.

Influence of OATPs on Hepatic Disposition of Erlotinib Measured With Positron Emission Tomography.

To assess the hepatic disposition of erlotinib, we performed positron emission tomography (PET) scans with [ C]erlotinib in healthy volunteers without and with oral pretreatment with a therapeutic erlotinib dose (300 mg). Erlotinib pretreatment significantly decreased the liver exposure to [ C]erlotinib with a concomitant increase in blood exposure, pointing to the involvement of a carrier-mediated hepatic uptake mechanism. Using cell lines overexpressing human organic anion-transporting polypeptides (OATPs) 1B1, 1B3, or 2B1, we show that [ C]erlotinib is selectively transported by OATP2B1.

The high turnover Drosophila multidrug resistance-associated protein shares the biochemical features of its human orthologues.

DMRP, an ABC transporter encoded by the dMRP/CG6214 gene, is the Drosophila melanogaster orthologue of the "long" human multidrug resistance-associated proteins (MRP1/ABCC1, MRP2/ABCC2, MRP3/ABCC3, MRP6/ABCC6, and MRP7/ABCC10). In order to provide a detailed biochemical characterisation we expressed DMRP in Sf9 insect cell membranes. We demonstrated DMRP as a functional orthologue of its human counterparts capable of transporting several human MRP substrates like beta-estradiol 17-beta-D-glucuronide, leukotriene C4, calcein, fluo3 and carboxydichlorofluorescein.

State-dependent inhibition of cystic fibrosis transmembrane conductance regulator chloride channels by a novel peptide toxin.

Peptide toxins from animal venom have been used for many years for the identification and study of cation-permeable ion channels. However, no peptide toxins have been identified that interact with known anion-selective channels, including cystic fibrosis transmembrane conductance regulator (CFTR), the protein defective in cystic fibrosis and a member of the ABC transporter superfamily. Here, we describe the identification and initial characterization of a novel 3.