Curcumin as an In Vivo Selective Intestinal Breast Cancer Resistance Protein Inhibitor in Cynomolgus Monkeys

Enhanced in-vitro bioavailability of curcumin, lutein and isoflavones through interaction with spearmint (Mentha spicata) via its bioactive component (R)-(-)-carvone

Numerous dietary phytochemicals such as curcumin, lutein and isoflavones are associated with health beneficial activities, however their application is often limited by their low bioavailability. Therefore, bioenhancers represent a feasible approach to increase the absorption efficiency of bioactive compounds. Here, we combined uptake and transport studies in differentiated Caco-2 cells with high resolution analytics and fractionation to evaluate the impact of spearmint (Mentha spicata) on the cellular uptake of curcumin. Additionally, we utilized mechanistic studies in native and overexpressing cell systems to assess P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) efflux transporter activity as well as in-silico molecular docking simulations. We found significantly elevated intracellular curcuminoid levels mediated by spearmint. Fractionation and functional assays identified (R)-(-)-carvone as a putative candidate for the biologically active compound mediating increased curcumin uptake via BCRP inhibition. Inhibition of P-gp-mediated efflux might additionally be involved. Molecular docking simulations suggest a common binding site of curcumin and (R)-(-)-carvone in BCRP. Further, spearmint significantly increased cellular uptake of lutein and transintestinal transport of isoflavones in-vitro. In summary, spearmint was identified as a novel bioenhancer for curcumin, lutein and isoflavones. Our findings suggest that spearmint increases bioavailability of a wide range of nutrients and drugs at least partially due to interference with BCRP via its active compound (R)-(-)-carvone.

Contribution of Japanese scientists to drug metabolism and disposition

Japanese researchers have played a pivotal role in advancing the field of drug metabolism and disposition, as demonstrated by their substantial contributions to the journal Drug Metabolism and Disposition (DMD) over the past 5 decades. This review highlights the historical and ongoing impact of Japanese scientists on DMD, celebrating their achievements in elucidating drug metabolism, membrane transport, pharmacokinetics, and toxicology. From the discovery of cytochrome P450 by Tsuneo Omura and Ryo Sato in 1962 to subsequent advances in drug transport research, Japan has maintained a leading position in the field. A geographical analysis of DMD publications reveals a notable increase in contributions from Japan during the 1980s, ranking second globally and maintaining this position through the 2000s. However, recent years have seen a slight decline in output, likely influenced by the COVID-19 pandemic and increased online journals as well as structural changes within academia and industry. Importantly, this trend is not unique to Japan. To sustain excellence and innovation in this field, it is crucial to strengthen funding for absorption, distribution, metabolism, excretion, and toxicity research and promote collaborations between academia, industry, and regulatory agencies. By prioritizing the translation of fundamental discoveries into drug development and clinical applications, scientists in this area can further advance global efforts toward achieving optimal drug efficacy and safety. This review underscores the enduring contributions of Japanese researchers to DMD and calls for renewed efforts to drive innovation and progress in this vital area of science. SIGNIFICANCE STATEMENT: Over the past 5 decades, Japanese scientists have made significant contributions to Drug Metabolism and Disposition through groundbreaking discoveries and advancements in the study of drug-metabolizing enzymes, transporters, pharmacokinetics analysis, and related areas. These contributions continue to shape the field, offering a foundation for future innovation in this area. We hope that the next generation of Japanese scientists will further solidify their global leadership in this area to advance drug development and proper pharmacotherapy.

A comprehensive review on pharmacokinetic mechanism of herb-herb/drug interactions in Chinese herbal formula

Oral administration of Chinese Herbal Medicine (CHM) faces various challenges in reaching the target organs including absorption and conversion in the gastrointestinal tract, hepatic metabolism via the portal vein, and eventual systemic circulation. During this process, factors such as gut microbes, physical or chemical barriers, metabolic enzymes, and transporters play crucial roles. Particularly, interactions between different herbs in CHM have been observed both in vitro and in vivo. In vitro, interactions typically manifest as detectable physical or chemical changes, such as facilitating solubilization or producing precipitates when decoctions of multiple herbs are administered. In vivo, such interactions cause alterations in the ADME (absorption, distribution, metabolism, and excretion) profile on metabolic enzymes or transporters in the body, leading to competition, antagonism, inhibition, or activation. These interactions ultimately contribute to differences in the therapeutic and pharmacological effects of multi-herb formulas in CHM. Over the past two thousand years, China has cultivated profound expertise and solid theoretical frameworks over the scientific use of herbs. The combination of multiple herbs in one decoction has been frequently employed to synergistically enhance therapeutic efficacy or mitigate toxic and side effects in clinical settings. Additionally combining herbs with increased toxicity or decreased effect is also regarded as a remedy, a practice that should be approached with caution according to Traditional Chinese Medicine (TCM) physicians. Such historical records and practices serve as a foundation for predicting favorable multi-herb combinations and their potential risks. However, systematic data that are available to support the clinical practice and the exploration of novel herbal formulas remain limited. Therefore, this review aims to summarize the pharmacokinetic interactions and mechanisms of herb-herb or herb-drug combinations from existing works, and to offer guidance as well as evidence for optimizing CHM and developing new medicines with CHM characteristics.

Drug Interaction-Informed Approaches to Inflammatory Bowel Disease Management

Inflammatory bowel disease (IBD) is a complex and chronic condition that requires the use of various pharmacological agents for its management. Despite advancements in IBD research, the multifaceted mechanisms involved continue to pose significant challenges for strategic prevention. Therefore, it is crucial to prioritize safe and effective treatment strategies using the currently available pharmacological agents. Given that patients with IBD often require multiple medications due to combination therapy or other underlying conditions, a comprehensive understanding of drug interactions is essential for optimizing treatment regimens. In this review, we examined the pharmacological treatment options recommended in the current IBD management guidelines and provided a comprehensive analysis of the known pharmacokinetic interactions associated with these medications. In particular, this review includes recent research results for the impact of anti-drug antibodies (ADAs) on the concentrations of biological agents used in IBD treatment. By leveraging detailed interaction data and employing personalized dosing strategies, healthcare providers can improve therapeutic outcomes and minimize adverse effects, ultimately improving the quality of care for patients with IBD.

A Phase 1 Study to Assess the Pharmacokinetics, Food Effect, Safety, and Tolerability of Sepiapterin in Healthy Japanese and Non-Japanese Participants

BACKGROUND

Sepiapterin is a natural precursor of tetrahydrobiopterin (BH4), a key cofactor for phenylalanine hydroxylase. It is being developed for the treatment of patients with phenylketonuria. In this study, the ethnic differences in pharmacokinetics and safety of sepiapterin in Japanese and non-Japanese participants and food effects were evaluated.

METHODS

Healthy participants (n = 60) received a single oral dose of sepiapterin at either 20, 40, or 60 mg/kg with a low-fat diet. The Japanese participants received two doses at 40 mg/kg, either under fasted conditions or with a low-fat diet with a 3-day washout period in between.

RESULTS

Sepiapterin was well tolerated in all participants, with no serious adverse events. Sepiapterin was quickly absorbed (Tmax 1.4-4.5 h) and rapidly and extensively converted to BH4 (Tmax ~4 h). Exposures to sepiapterin were <1% of BH4. BH4 exposures were essentially dose-independent between 20 and 60 mg/kg. A low-fat diet increased BH4 exposures in Japanese participants by 1.7-fold compared with fasted conditions.

CONCLUSIONS

BH4 exposures (Cmax and AUC0-last) in Japanese participants were 10-30% higher than in non-Japanese participants, which is deemed not clinically relevant; no dose adjustment is warranted. The slightly higher BH4 exposures in Japanese participants are likely due to the higher frequency of ABCG2 c.421C>A mutation in the Japanese population.

Enhanced absorption of prenylated cinnamic acid derivatives from Brazilian green propolis by turmeric in humans and rats

Prenylated cinnamic acid derivatives are the bioactive components of Brazilian green propolis (BGP). The effect of other botanical components on the pharmacokinetic profiles of these derivatives remains relatively unexplored. In the present study, we investigated the influence of several herbal extracts (turmeric, ginkgo leaf, coffee fruit, soybean, and gotu kola) on the plasma concentrations of cinnamic acid derivatives after BGP consumption. When the herbal extracts were co-administered with BGP in the clinical study, the area under the curve (AUC) values of artepillin C and drupanin, the major BGP components in plasma, were significantly increased by 1.7- and 1.5-fold, respectively, compared to those after BGP administration alone. Among the herbal extracts administered to rats, turmeric extract increased the AUC. Furthermore, a bidirectional transport assay suggested that artepillin C and drupanin are substrates of breast cancer resistance protein (BCRP), a drug elimination transporter. These results suggest that curcumin-containing turmeric extract may increase the plasma concentrations of artepillin C and drupanin via BCRP. Our findings enabled us to estimate the food-herb and herb-herb interactions in vivo in foods and herbal medicines containing cinnamic acid derivatives and prenylated compounds.

Dual strategy to improve the oral bioavailability of efavirenz employing nanomicelles and curcumin as a bio-enhancer

The present investigation was focused on the development of Soluplus®-based nanomicelles (NMs) (10 % w/v) loaded with Efavirenz (EFV) (5 mg/mL) and Curcumin (natural bio-enhancer) (CUR) (5, 10 and 15 mg/mL) to improve the oral bioavalability of EFV. Micellar formulations were obtained employing an acetone-diffusion technique. Apparent aqueous solubility was increased up to ∼1250-fold and 25,000-fold for EFV and CUR, respectively. Drug-loaded nanoformulations showed an excellent colloidal stability with unimodal size distribution and PDI values < 0.30. In vitro drug release was 41.5 % (EFV) and 2.6 % (CUR) from EFV-CUR-NMs over 6 h in simulated gastrointestinal fluids. EFV-CUR-loaded NMs resulted as safe nanoformulations according to the in vitro cytocompatibility assays in Caco-2 cells. Furthermore, CUR bio-enhancer activity was demonstrated for those nanoformulations. A CUR concentration of 15 mg/mL produced a significant (p < 0.05) increment (2.64-fold) of relative EFV oral bioavailability. Finally, the active role of the lymphatic system in the absorption process of EFV, after its oral administration was assessed in a comparative pharmacokinetic study in presence and absence of cycloheximide, a lymphatic transport inhibitor. Overall our EFV-CUR-NMs denoted their potential as a novel nanotechnological platform, representing a step towards an optimized "nano-sized" therapy for AIDS patients.

Evaluation of Encequidar as An Intestinal P-gp and BCRP Specific Inhibitor to Assess the Role of Intestinal P-gp and BCRP in Drug-Drug Interactions

PURPOSE

The differences between intestinal and systemic (hepatic and renal) P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) roles in drug disposition are difficult to define. Accordingly, we characterized Encequidar (ECD) as an intestinal P-gp and BCRP specific inhibitor to evaluate their role in drug disposition.

METHODS

We assessed the in vitro and in vivo inhibition potential of ECD towards human and animal P-gp and BCRP.

RESULTS

ECD is a potent inhibitor with a high degree of selectivity in inhibiting human P-gp (hP-gp) over human BCRP (hBCRP) (IC50s of 0.0058 ± 0.0006 vs. > 10 µM, respectively). In contrast, ECD is a potent inhibitor of rat and cynomolgus monkey BCRP (IC50 ranged from 0.059 to 0.18 µM). While the AUC of IV paclitaxel (PTX) was significantly increased by elacridar (ELD) (P < 0.05) but not ECD in rats (15 mg/kg; PO) (2.55- vs. 0.93-fold), that of PO PTX was significantly elevated to a similar extent between the inhibitors (39.5- vs. 33.5-fold). Similarly, the AUC of PO sulfasalazine (SFZ) was dramatically increased by ELD and ECD (16.6- vs. 3.04-fold) although that of IV SFZ was not significantly affected by ELD and ECD in rats (1.18- vs. 1.06-fold). Finally, a comparable ECD-induced increase of the AUC of PO talinolol in cynomolgus monkeys was observed compared with ELD (2.14- vs. 2.12-fold).

CONCLUSIONS

ECD may allow an in-depth appraisal of the role of intestinal efflux transporter(s) in drug disposition in animals and humans through local intestinal drug interactions.

Metabolomic Profiling and Drug Interaction Characterization Reveal Riboflavin As a Breast Cancer Resistance Protein-Specific Endogenous Biomarker That Demonstrates Prediction of Transporter Activity In Vivo

Advancement of endogenous biomarkers for drug transporters as a tool for assessing drug-drug interactions (DDIs) depends on initial identification of biomarker candidates and relies heavily on biomarker validation and its response to reference inhibitors in vivo. To identify endogenous biomarkers of breast cancer resistance protein (BCRP), we applied metabolomic approaches to profile plasma from Bcrp-/-, multidrug resistance protein (Mdr)1a/1b-/-, and Bcrp/Mdr1a/1b-/- mice. Approximately 130 metabolites were significantly altered in Bcrp and P-glycoprotein (P-gp) knockout mice, indicating numerous metabolite-transporter interactions. We focused on BCRP-specific substrates and identified riboflavin, which was significantly elevated in the plasma of Bcrp single- and Bcrp/P-gp double- but not P-gp single-knockout mice. Dual BCRP/P-gp inhibitor elacridar caused a dose-dependent increase of the area under the plasma concentration-time curve (AUC) of riboflavin in mice (1.51- and 1.93-fold increases by 30 and 150 mg/kg elacridar, respectively). In three cynomolgus monkeys, we observed approximately 1.7-fold increases in the riboflavin concentrations caused by ML753286 (10 mg/kg), which correlated well with the increase of sulfasalazine, a known BCRP probe in monkeys. However, the BCRP inhibitor had no effect on isobutyryl carnitine, arginine, or 2-arachidonoyl glycerol levels. Additionally, clinical studies on healthy volunteers indicated low intrasubject and intermeal variability of plasma riboflavin concentrations. In vitro experiments using membrane vesicles demonstrated riboflavin as a select substrate of monkey and human BCRP over P-gp. Collectively, this proof-of-principle study indicates that riboflavin is a suitable endogenous probe for BCRP activity in mice and monkeys and that future investigation of riboflavin as a blood-based biomarker of human BCRP is warranted. SIGNIFICANCE STATEMENT: Our results identified riboflavin as an endogenous biomarker candidate of BCRP. Its selectivity, sensitivity, and predictivity regarding BCRP inhibition have been explored. The findings of this study highlight riboflavin as an informative BCRP plasma biomarker in animal models. The utility of this biomarker requires further validation by evaluating the effects of BCRP inhibitors of different potencies on riboflavin plasma concentrations in humans. Ultimately, riboflavin may shed light on the risk assessment of BCRP DDIs in early clinical trials.

O-Sulfation disposition of curcumin and quercetin in SULT1A3 overexpressing HEK293 cells: the role of arylsulfatase B in cellular O-sulfation regulated by transporters

Extensive phase II metabolic reactions (i.e., glucuronidation and sulfation) have resulted in low bioavailability and decreased biological effects of curcumin and quercetin. Compared to glucuronidation, information on the sulfation disposition of curcumin and quercetin is limited. In this study, we identified that BCRP and MRP4 played a critical role in the cellular excretion of curcumin-O-sulfate (C-O-S) and quercetin-O-sulfate (Q-O-S) by integrating chemical inhibition with transporter knock-down experiments. Inhibited excretion of sulfate (C-O-S and Q-O-S) caused significant reductions in cellular O-sulfation of curcumin (a maximal 74.4% reduction) and quercetin (a maximal 76.9% reduction), revealing a strong interplay of sulfation with efflux transport. It was further identified that arylsulfatase B (ARSB) played a crucial role in the regulation of cellular O-sulfation by transporters. ARSB overexpression significantly enhanced the reduction effect of MK-571 on the cellular O-sulfation (f_met) of the model compound (38.8% reduction for curcumin and 44.2% reduction for quercetin). On the contrary, ARSB knockdown could reverse the effect of MK-571 on the O-sulfation disposition of the model compound (29.7% increase for curcumin and 47.3% increase for quercetin). Taken together, ARSB has been proven to be involved in cellular O-sulfation, accounting for transporter-dependent O-sulfation of curcumin and quercetin. A better understanding of the interplay beneath metabolism and transport will contribute to the exact prediction of in vivo drug disposition and drug-drug interactions.

Cynomolgus Monkey as an Emerging Animal Model to Study Drug Transporters: In Vitro, In Vivo, In Vitro-to-In Vivo Translation

Membrane transporters have been recognized as one of the key determinants of pharmacokinetics and are also known to affect the efficacy and toxicity of drugs. Both qualitatively and quantitatively, however, transporter studies conducted using human in vitro systems have not always been predictive. Consequently, researchers have used cynomolgus monkeys as a model to study drug transporters and anticipate their effects in humans. Burgeoning reports of data in the last few years necessitates a comprehensive review on the topic of drug transporters in cynomolgus monkeys that includes cell-based tools, sequence homology, tissue expression, in vitro studies, in vivo studies, and in vitro-to-in vivo extrapolation. This review highlights the state-of-the-art applications of monkey transporter models to support the evaluation of transporter-mediated drug-drug interactions, clearance predictions, and endogenous transporter biomarker identification and validation. The data demonstrate that cynomolgus monkey transporter models, when used appropriately, can be an invaluable tool to support drug discovery and development processes. Most importantly, they enable an early in vitro-to-in vivo extrapolation assessment, which provides additional context to human in vitro data. Additionally, comprehending species similarities and differences in transporter tissue expression and activity is crucial when translating monkey data to humans. The challenges and limitations when applying such models to inform decision-making must also be considered. SIGNIFICANCE STATEMENT: This paper presents a comprehensive review of currently available published reports describing cynomolgus monkey transporter models. The data indicate that Cynomolgus monkeys provide mechanistic insight regarding the role of intestinal, hepatic, and renal transporters in drug and biomarker disposition and drug interactions. The data generated with cynomolgus monkey models provide mechanistic insight into transporter-mediated drug absorption and disposition. They are valuable to human clearance prediction, drug drug interaction assessment, and endogenous biomarker development related to drug transporters.

Cloning and tissue expression of ATP-binding cassette transporters in cynomolgus macaques

Cynomolgus macaques are used in preclinical studies in part because of their evolutionary closeness to humans. However, drug transporters, including ATP-binding cassette (ABC) transporters, which are essential for the absorption and excretion of drugs, have not been fully investigated at the molecular level in cynomolgus macaques. In this study, ABCB4, ABCC3, ABCC4, and ABCG2 cDNAs were newly identified and characterized, along with ABCB1, ABCB11, and ABCC2 cDNAs previously identified, in cynomolgus macaques. All seven cynomolgus ABC transporters had high sequence identities (96-98%) with their human orthologs in terms of amino acid sequences and were also most closely clustered with their human orthologs by phylogenetic analysis. Furthermore, the gene structures and genomic organization were similar in cynomolgus macaques and humans. The mRNAs of these cynomolgus ABC transporters, as analyzed using the quantitative polymerase chain reaction, showed distinct tissue expression patterns. Among the ten tissues, ABCB1, ABCC2, ABCC3, and ABCG2 mRNAs were most abundantly expressed in jejunum; ABCB4 and ABCB11 in liver; and ABCC4 in kidney, which are similar to the expression patterns of human ABC transporters. These results suggest molecular similarities of the ABC transporters in cynomolgus macaques and humans.

Acute regulation of apical ABC transporters in the gut. Potential influence on drug bioavailability

The extensive intestinal surface offers an advantage regarding nutrient, ion and water absorptive capacity but also brings along a high exposition to xenobiotics, including drugs of therapeutic use and food contaminants. After absorption of these compounds by the enterocytes, apical ABC transporters play a key role in secreting them back to the intestinal lumen, hence acting as a transcellular barrier. Rapid and reversible modulation of their activity is a subject of increasing interest for pharmacologists. On the one hand, a decrease in transporter activity may result in increased absorption of therapeutic agents given orally. On the other hand, an increase in transporter activity would decrease their absorption and therapeutic efficacy. Although of less relevance, apical ABC transporters also contribute to disposition of drugs systemically administered. This review article summarizes the present knowledge on the mechanisms aimed to rapidly regulate the activity of the main apical ABC transporters of the gut: multidrug resistance protein 1 (MDR1), multidrug resistance-associated protein 2 (MRP2) and breast cancer resistance protein (BCRP). Regulation of these mechanisms by drugs, drug delivery systems, drug excipients and nutritional components are particularly considered. This information could provide the basis for controlled regulation of bioavailability of therapeutic agents and at the same time would help to prevent potential drug-drug interactions.

Multidrug Resistance-Associated Protein 3 Is Responsible for the Efflux Transport of Curcumin Glucuronide from Hepatocytes to the Blood

Curcumin, a major polyphenol present in turmeric, is predominantly converted to curcumin-O-glucuronide (COG) in enterocytes and hepatocytes via glucuronidation. COG is a principal metabolite of curcumin in plasma and feces. It appears that the efflux transport of the glucuronide conjugates of many compounds is mediated largely by multidrug resistance-associated protein (MRP) 3, the gene product of the ATP-binding cassette, subfamily C, member 3. However, it is currently unknown whether this was the case with COG. In this study, Mrp3 knockout (KO) and wild-type (WT) mice were used to evaluate the pharmacokinetics profiles of COG, the liver-to-plasma ratio of COG, and the COG-to-curcumin ratio in plasma, respectively. The ATP-dependent uptake of COG into recombinant human MRP3 inside-out membrane vesicles was measured for further identification, with estradiol-17β-d-glucuronide used in parallel as the positive control. Results showed that plasma COG concentrations were extremely low in KO mice compared with WT mice, that the liver-to-plasma ratios of COG were 8-fold greater in KO mice than in WT mice, and that the ATP-dependent uptake of COG at 1 or 10 μM was 5.0- and 3.1-fold greater in the presence of ATP than in the presence of AMP, respectively. No significant differences in the Abcc2 and Abcg2 mRNA expression levels were seen between Mrp3 KO and WT mice. We conclude that Mrp3 is identified to be the main efflux transporter responsible for the transport of COG from hepatocytes into the blood. SIGNIFICANCE STATEMENT: This study was designed to determine whether multidrug resistance-associated protein (Mrp) 3 could be responsible for the efflux transport of curcumin-O-glucuronide (COG), a major metabolite of curcumin present in plasma and feces, from hepatocytes into the blood using Mrp3 knockout mice. In this study, COG was identified as a typical Mrp3 substrate. Results suggest that herb-drug interactions would occur in patients concomitantly taking curcumin and either an MRP3 substrate/inhibitor or a drug that is predominantly glucuronidated by UDP-glucuronosyltransferases.

Nutrigenomics-Associated Impacts of Nutrients on Genes and Enzymes With Special Consideration of Aromatase

Interactions are occurring in the course of liberation, absorption, distribution, metabolism, and excretion of active ingredients, or at the target receptors. They are causing therapy failures and undesirable events. Forty-seven of fifty-seven human hepatic isoenzymes are specific and relevant in hormone and vitamin metabolism and biosynthesis. Aromatase (syn. CYP19A1) is one of the specific CYP450 isoenzymes so far not elucidated in detail. As aromatase-inhibiting phytochemicals are currently recommended for breast cancer prevention and as add-on accompanying aromatase-inhibitor pharmacotherapy, it was the aim of this literature review to assess whether a common interpretation on genetic and -omics basis could be found. Articles retrieved showed that traditional antioxidation diet is one of the most approved explanations of inhibition of aromatase by phytonutrients of flavonoid derivatives. Flavonoids compete for the oxygen provided by the heme moiety of aromatase in the course of aromatase-catalyzed conversion of steroid precursors to estrogens. Flavonoids are therefore promoted for breast cancer prevention. A further explanation of flavonoids' mechanism of action proposed was related to enzymatic histone deacetylation. By keeping DNA-structure wide through a high acetylation degree, acetylated histones favor transcription and replication. This mechanism corresponds to a procedure of switching genes on. Inhibiting acetylation and therefore switching genes off might be an important regulation of repressing cancer genes. Aromatase expression depends on the genotype and phenotype of a person. Aromatase itself depends on the expression of the heme moiety encoded in the genotype. Biosynthesis of porphyrins in turn depends on the substrates succinate and glycine, as well as on a series of further enzymes, with ALA synthetase as the rate-limiting step. The effect of the heme moiety as prosthetic group of aromatase further depends on the absorption of iron as a function of pH and redox state. To assess the function of aromatase precisely, multiple underlying biochemical pathways need to be evaluated. As a conclusion, the genetic regulation of metabolism is a complex procedure affecting multiple pathways. To understand a metabolic step, multiple underlying individually performing reactions need to be considered if personalized (nutritional) medicine should bring an advantage for a patient. Nutrition sciences need to consider the genome of an individual to truly find answers to nutrition-derived non-communicable diseases. With current GWAS (genome-wide association study) approaches, inherited errors of metabolism are identified and ideally treated effectively. It is much more difficult to get a precise genetic profile for non-communicable diseases stemming from multifactorial causes. Polygenic risks evaluation is feasible but diagnostic tools are not yet available in a desired extent. Neither flavonoid researchers nor providers of genetic testing kits are going into the details needed for a truly personalized nutritional medicine. The next step with profiling the exome and then the whole genome is on the threshold of becoming routine diagnosis and of bringing the desired details.

Interactions of Oral Molecular Excipients with Breast Cancer Resistance Protein, BCRP

Mechanistic-understanding-based selection of excipients may improve formulation development strategies for generic drug products and potentially accelerate their approval. Our study aimed at investigating the effects of molecular excipients present in orally administered FDA-approved drug products on the intestinal efflux transporter, BCRP (ABCG2), which plays a critical role in drug absorption with potential implications on drug safety and efficacy. We determined the interactions of 136 oral molecular excipients with BCRP in isolated membrane vesicles and identified 26 excipients as BCRP inhibitors with IC₅₀ values less than 5 μM using ³H-cholecystokinin octapeptide (³H-CCK8). These BCRP inhibitors belonged to three functional categories of excipients: dyes, surfactants, and flavoring agents. Compared with noninhibitors, BCRP inhibitors had significantly higher molecular weights and SLogP values. The inhibitory effects of excipients identified in membrane vesicles were also evaluated in BCRP-overexpressing HEK293 cells at similar concentrations. Only 1 of the 26 inhibitors of BCRP identified in vesicles inhibited BCRP-mediated ³H-oxypurinol uptake by more than 50%, consistent with the notion that BCRP inhibition depends on transmembrane or intracellular availability of the inhibitors. Collectively, the results of this study provide new information on excipient selection during the development of drug products with active pharmaceutical ingredients that are BCRP substrates.

Current trends in drug metabolism and pharmacokinetics

Pharmacokinetics (PK) is the study of the absorption, distribution, metabolism, and excretion (ADME) processes of a drug. Understanding PK properties is essential for drug development and precision medication. In this review we provided an overview of recent research on PK with focus on the following aspects: (1) an update on drug-metabolizing enzymes and transporters in the determination of PK, as well as advances in xenobiotic receptors and noncoding RNAs (ncRNAs) in the modulation of PK, providing new understanding of the transcriptional and posttranscriptional regulatory mechanisms that result in inter-individual variations in pharmacotherapy; (2) current status and trends in assessing drug-drug interactions, especially interactions between drugs and herbs, between drugs and therapeutic biologics, and microbiota-mediated interactions; (3) advances in understanding the effects of diseases on PK, particularly changes in metabolizing enzymes and transporters with disease progression; (4) trends in mathematical modeling including physiologically-based PK modeling and novel animal models such as CRISPR/Cas9-based animal models for DMPK studies; (5) emerging non-classical xenobiotic metabolic pathways and the involvement of novel metabolic enzymes, especially non-P450s. Existing challenges and perspectives on future directions are discussed, and may stimulate the development of new research models, technologies, and strategies towards the development of better drugs and improved clinical practice.

Mechanism of the efflux transport of demethoxycurcumin-O-glucuronides in HeLa cells stably transfected with UDP-glucuronosyltransferase 1A1

Demethoxycurcumin (DMC) is a safe and natural food-coloring additive, as well as an agent with several therapeutic properties. However, extensive glucuronidation in vivo has resulted in its poor bioavailability. In this study, we aimed to investigate the formation of DMC-O-glucuronides by uridine 5'-diphospho-glucuronosyltransferase 1A1 (UGT1A1) and its transport by breast cancer resistance protein (BCRP) and multidrug resistance-associated proteins (MRPs) in HeLa cells stably transfected with UGT1A1 (named HeLa1A1 cells). The chemical inhibitors Ko143 (a selective BCRP inhibitor) and MK571 (a pan-MRP inhibitor) both induced an obvious decrease in the excretion rate of DMC-O-glucuronides and a significant increase in intracellular DMC-O-glucuronide concentrations. Furthermore, BCRP knock-down resulted in a marked reduction in the level of excreted DMC-O-glucuronides (maximal 55.6%), whereas MRP1 and MRP4 silencing significantly decreased the levels of excreted DMC-O-glucuronides (a maximum of 42.9% for MRP1 and a maximum of 29.9% for MRP3), respectively. In contrast, neither the levels of excreted DMC-O-glucuronides nor the accumulation of DMC-O-glucuronides were significantly altered in the MRP4 knock-down HeLa cells. The BCRP, MRP1 and MRP3 transporters were identified as the most important contributors to the excretion of DMC-O-glucuronides. These results may significantly contribute to improving our understanding of mechanisms underlying the cellular disposition of DMC via UGT-mediated metabolism.

ABCG2/BCRP: variants, transporter interaction profile of substrates and inhibitors

INTRODUCTION

ABCG2 has a broad substrate specificity and is one of the most important efflux proteins modulating pharmacokinetics of drugs, nutrients and toxicokinetics of toxicants. ABCG2 is an important player in transporter-mediated drug-drug interactions (tDDI). Areas covered: The aims of the review are i) to cover transporter interaction profile of substrates and inhibitors that can be utilized to test interaction of drug candidates with ABCG2, ii) to highlight main characteristics of in vitro testing and iii) to describe the structural basis of the broad substrate specificity of the protein. Preclinical data utilizing Abcg2/Bcrp1 knockouts and clinical studies showing effect of ABCG2 c.421C>A polymorphism on pharmacokinetics of drugs have provided evidence for a broad array of drug substrates and support drug - ABCG2 interaction testing. A consensus on using rosuvastatin and sulfasalazine as intestinal substrates for clinical studies is in the formation. Other substrates relevant to the therapeutic area can be considered. Monolayer efflux assays and vesicular transport assays have been extensively utilized in vitro. Expert opinion: Clinical substrates display complex pharmacokinetics due to broad interaction profiles with multiple transporters and metabolic enzymes. Substrate-dependent inhibition has been observed for several inhibitors. Harmonization of in vitro and in vivo testing makes sense. However, rosuvastatin and sulfasalazine are not efficiently transported in either MDCKII or LLC-PK1-based monolayers. Caco-2 monolayer assays and vesicular transport assays are potential alternatives.

The Antimicrobials Anacardic Acid and Curcumin Are Not-Competitive Inhibitors of Gram-Positive Bacterial Pathogenic Glyceraldehyde-3-Phosphate Dehydrogenase by a Mechanism Unrelated to Human C5a Anaphylatoxin Binding

The ubiquitous and highly abundant glycolytic enzyme D-glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is pivotal for the energy and carbon metabolism of most organisms, including human pathogenic bacteria. For bacteria that depend mostly on glycolysis for survival, GAPDH is an attractive target for inhibitor discovery. The availability of high-resolution structures of GAPDH from various pathogenic bacteria is central to the discovery of new antibacterial compounds. We have determined the X-ray crystal structures of two new GAPDH enzymes from Gram-positive bacterial pathogens, Streptococcus pyogenes and Clostridium perfringens. These two structures, and the recent structure of Atopobium vaginae GAPDH, reveal details in the active site that can be exploited for the design of novel inhibitors based on naturally occurring molecules. Two such molecules, anacardic acid and curcumin, have been found to counter bacterial infection in clinical settings, although the cellular targets responsible for their antimicrobial properties remain unknown. We show that both anacardic acid and curcumin inhibit GAPDH from two bacterial pathogens through uncompetitive and non-competitive mechanisms, suggesting GAPDH as a relevant pharmaceutical target for antibacterial development. Inhibition of GAPDH by anacardic acid and curcumin seems to be unrelated to the immune evasion function of pathogenic bacterial GAPDH, since neither natural compound interfere with binding to the human C5a anaphylatoxin.

Efflux excretion of bisdemethoxycurcumin-O-glucuronide in UGT1A1-overexpressing HeLa cells: Identification of breast cancer resistance protein (BCRP) and multidrug resistance-associated proteins 1 (MRP1) as the glucuronide transporters

Bisdemethoxycurcumin (BDMC) was a natural curcuminoid with many bioactivities present in turmeric (Curcuma longa L.). However, the disposition mechanisms of BDMC via uridine 5'-diphospho-glucuronosyltransferase (UGT) metabolism still remain unclear. Therefore, we aimed to determine the potential efflux transporters for the excretion of BDMC-O-glucuronide. Herein, chemical inhibition assays (Ko143, MK571, dipyridamole, and leukotriene C4) and biological inhibition experiments including stable knocked-down of breast cancer resistance protein (BCRP), multidrug resistance-associated proteins (MRPs) transporters were both performed in a HeLa cell line stably overexpressing UGT1A1 established previously. The results indicated that Ko143 (5 and 20 μM) caused a marked reduction in excretion rate (18.4-55.6%) and elevation of intracellular BDMC-O-glucuronide (28.8-48.1%), whereas MK-571 (5 and 20 μM) resulted in a significant decrease in excretion rate (6.2-61.6%) and increase of intracellular BDMC-O-glucuronide (maximal 27.1-32.6%). Furthermore, shRNA-mediated silencing of BCRP transporter led to a marked reduction in the excretion rate (21.1-36.9%) and an obvious elevation of intracellular glucuronide (24.9%). Similar results were observed when MRP1 was partially silenced. In addition, MRP3 and MRP4 silencing both displayed no obvious changes on the excretion rate and intracellular levels of glucuronide. In conclusion, chemical inhibition and gene silencing results both indicated that generated BDMC-O-glucoside were excreted primarily by the BCRP and MRP1 transporters. © 2018 BioFactors, 44(6):558-569, 2018.

Simultaneous Assessment of Transporter-Mediated Drug-Drug Interactions Using a Probe Drug Cocktail in Cynomolgus Monkey

We aim to establish an in vivo preclinical model to enable simultaneous assessment of inhibition potential of an investigational drug on clinically relevant drug transporters, organic anion-transporting polypeptide (OATP)1B, breast cancer resistance protein (BCRP), P-glycoprotein (P-gp), and organic anion transporter (OAT)3. Pharmacokinetics of substrate cocktail consisting of pitavastatin (OATP1B substrate), rosuvastatin (OATP1B/BCRP/OAT3), sulfasalazine (BCRP), and talinolol (P-gp) were obtained in cynomolgus monkey-alone or in combination with transporter inhibitors. Single-dose rifampicin (30 mg/kg) significantly (P < 0.01) increased the plasma exposure of all four drugs, with a marked effect on pitavastatin and rosuvastatin [area under the plasma concentration-time curve (AUC) ratio ∼21-39]. Elacridar, BCRP/P-gp inhibitor, increased the AUC of sulfasalazine, talinolol, as well as rosuvastatin and pitavastatin. An OAT1/3 inhibitor (probenecid) significantly (P < 0.05) impacted the renal clearance of rosuvastatin (∼8-fold). In vitro, rifampicin (10 µM) inhibited uptake of pitavastatin, rosuvastatin, and sulfasalazine by monkey and human primary hepatocytes. Transport studies using membrane vesicles suggested that all probe substrates, except talinolol, are transported by cynoBCRP, whereas talinolol is a cynoP-gp substrate. Elacridar and rifampicin inhibited both cynoBCRP and cynoP-gp in vitro, indicating potential for in vivo intestinal efflux inhibition. In conclusion, a probe substrate cocktail was validated to simultaneously evaluate perpetrator impact on multiple clinically relevant transporters using the cynomolgus monkey. The results support the use of the cynomolgus monkey as a model that could enable drug-drug interaction risk assessment, before advancing a new molecular entity into clinical development, as well as providing mechanistic insights on transporter-mediated interactions.

Drug Transporters in Xenobiotic Disposition and Pharmacokinetic Prediction

Drug transporters are widely expressed in organs and tissue barriers throughout human and animal bodies. Studies over the last two decades have identified various ATP-binding cassette and solute carrier transporters that play critical roles in the absorption, distribution, metabolism, and elimination of drugs and xenobiotics. This special section contains more than 20 original manuscripts and reviews that cover the most recent advances in the areas of drug transporter research, including the basic biology and function of transporters, expression of drug transporters in organ and tissue barriers, the mechanisms underlying regulation of transporter expression, transporter-mediated drug disposition in animal models, and the development and utilization of new technologies in drug transporter study, as well as pharmacokinetic modeling and simulation to assess transporter involvement in drug disposition and drug-drug interactions. We believe that the topics covered in this special section will advance our understanding of the roles of transporters in drug disposition, efficacy, and safety.