P-glycoprotein: new insights into structure, physiological function, regulation and alterations in disease

Insights into interactions between taxanes and P-glycoprotein using biophysical and in silico methods

Multidrug resistance mediated by P-glycoprotein (Pgp) is a significant obstacle to cancer chemotherapy. Taxane drugs, including paclitaxel, docetaxel, and cabazitaxel, are used to treat multiple types of cancer. All taxane drugs are Pgp substrates, but cabazitaxel is also a Pgp inhibitor, indicating potential differential interactions between Pgp and different taxanes. Here, we showed for the first time that cabazitaxel had a partial inhibitory effect on the ATPase activity at concentrations higher than 10 µM. We found the KD of paclitaxel, docetaxel, and cabazitaxel to Pgp are 0.85 µM, 40.59 µM, and 13.53 µM, respectively. Based on acrylamide quenching, paclitaxel induced Pgp into a wide inward-facing open conformation at a high concentration but a slightly occluded conformation at lower concentrations. Both docetaxel and cabazitaxel shifted Pgp towards occluded states, each drug resulting in a unique degree of occlusion. Furthermore, molecular docking and energy calculations revealed that cabazitaxel binds with the "access tunnel" and blocks the subsequent nucleotide-binding domain dimerization. Our results indicate that the preference of taxanes for different binding sites on Pgp leads to distinct transport mechanisms. These results provide valuable insight into the interaction between taxanes and Pgp, which will enhance future drug development.

Molecular Docking Appraisal of Pleurotus ostreatus Phytochemicals as Potential Inhibitors of PI3K/Akt Pathway for Breast Cancer Treatment

Introduction

Breast cancer (BC) is a heterogeneous disease involving a network of numerous extracellular signal transduction pathways. The phosphoinositide 3-kinase (PI3K)/serine/threonine kinase (Akt)/mechanistic target of rapamycin (mTOR) pathway is crucial for understanding the BC development. Phosphoinositide 3-kinase, phosphatase and tensin homolog (PTEN), mTOR, Akt, 3-phosphoinositide-dependent kinase 1 (PDK1), FoxO1, glycogen synthase kinase 3 (GSK-3), mouse double minute 2 (MDM2), H-Ras, and proapoptotic B-cell lymphoma 2 (BCL-2) family protein (BAD) proteins are key drivers of this pathway and potential therapeutic targets. Pleurotus ostreatus is an edible mushroom that is rich in flavonoids and phenols that can serve as potential inhibitors of proteins in the PI3K/Akt/mTOR pathway.

Aim

This study evaluated the anticancer properties of P ostreatus through a structure-based virtual screening of 22 biologically active compounds present in the mushroom.

Method

Model optimization was carried out on PI3K, PTEN, mTOR, Akt, PDK1, FoxO1, GSK-3, MDM2, H-Ras, and BAD proteins in the PI3K/Akt/mTOR pathway and molecular docking of compounds/control inhibitors in the binding pocket were simulated AutoDock Vina in PyRx. The drug likeness, pharmacokinetic, and pharmacodynamic features of prospective docking leads were all anticipated.

Result

Several potent inhibitors of the selected key driver proteins in PI3K/Akt/mTOR pathway were identified from P ostreatus. Ellagic acid with binding affinities of -8.0, -8.0, -8.1, -8.2, -6.2, and -7.1 kcal/mol on PI3K, Akt, PDK1, GSK-3, MDM2, and BAD, respectively, had better binding affinity compared with their reference drugs. Likewise, apigenin (-7.8 kcal/mol), chrysin (-7.8 kcal/mol), quercetin (-6.4 kcal/mol), and chlorogenic acid (-6.2 kcal/mol) had better binding affinities to PTEN, mTOR, FoxO1, and H-Ras proteins, respectively.

Conclusion

Ellagic acid, apigenin, luteolin, quercetin, chlorogenic acid, chrysin, and naringenin phytochemicals are seen as the better lead molecules due to their ability to strongly bind to the proteins under study in this pathway. Analogs of these compounds can also be designed as potential drugs.

Improving Understanding of Fexofenadine Pharmacokinetics to Assess Pgp Phenotypic Activity in Older Adult Patients Using Population Pharmacokinetic Modeling

BACKGROUND AND OBJECTIVE

Fexofenadine is commonly used as a probe substrate to assess P-glycoprotein (Pgp) activity. While its use in healthy volunteers is well documented, data in older adult and polymorbid patients are lacking. Age- and disease-related physiological changes are expected to affect the pharmacokinetics of fexofenadine. This study aims to investigate the pharmacokinetics of fexofenadine in hospitalized older adult patients as a potential marker of Pgp activity, using data from the OptimAT study (ClinicalTrials.gov identifier: NCT03477331).

METHODS

Population pharmacokinetic (popPK) modeling was conducted using data from 449 hospitalized patients with a median age of 71 years (range: 25-97) and 10 healthy volunteers (median age: 23 years, range: 20-36). Fexofenadine plasma concentrations were analyzed using a refined two-compartment model with sequential zero/first-order absorption, while investigating the impact of covariates such as age, renal function, and Pgp inhibitors on fexofenadine pharmacokinetics.

RESULTS

Age, renal insufficiency, and Pgp inhibitors significantly influenced fexofenadine exposure. Renal function was a key factor, with AUC0-6 increasing by 79% in mild-to-moderate and by 154% in moderate-to-severe renal impairment compared with normal renal function. Co-administration of Pgp inhibitors led to a 35% increase in AUC0-6. Across chronic kidney disease (CKD) stages, age, and Pgp inhibitor status, fexofenadine AUC0-6 ratio ranged from 1.15 (stage 1, 20-30 years) to 4.59 (stage 5, 91-100 years, with Pgp inhibitors), relative to a reference subject of 20 years, normal renal function, and no Pgp inhibitors.

CONCLUSION

Clinicians should consider the risk of Pgp substrate accumulation in older adults, particularly those with advanced renal impairment. We propose typical values stratified by age and renal function to assist in interpreting Pgp phenotyping using fexofenadine exposure, thereby supporting drug optimization in this population. Further studies are needed to explore underlying mechanisms, such as reduced Pgp activity or expression.

Oral Administration of [18F]MC225 for Quantification of P-glycoprotein Function: A Feasibility Study

PURPOSE

This preclinical study explored the feasibility of assessing P-glycoprotein (P-gp) function in both brain and gastrointestinal (GI) tract of rats using positron emission tomography (PET) following oral administration of [18F]MC225. Different oral administration protocols were evaluated, and radioactivity uptake was compared with uptake following intravenous administration.

PROCEDURES

Twelve male Wistar rats were divided into four groups and subjected to intravenous or oral [18F]MC225 administration protocols: G1 (intravenous route), G2 (oral administration without fasting), G3 (oral administration with fasting), and G4 (oral administration with fasting following administration of the P-gp inhibitor tariquidar). Dynamic brain imaging, late abdominal imaging, ex vivo biodistribution, and metabolite analysis were conducted to assess tracer distribution.

RESULTS

In the brain, oral administration yielded lower values compared with intravenous administration, resulting in a reduction in the tissue-to-plasma ratio by approximately 51% for the cortex and 45% for the midbrain and cerebellum. Fasting improved radioactivity uptake, aiding brain visualization. Unexpectedly, administration of the P-gp inhibitor tariquidar did not increase brain concentration, suggesting a signal that was dominated by non-specific uptake, possibly due to instability of [18F]MC225 in the GI tract. Metabolite analysis in G4 indicated a significant presence of polar metabolites.

CONCLUSIONS

Oral administration of [18F]MC225 faces challenges and, at this stage, cannot be used to quantify P-gp function. Further research to assess tracer stability and metabolism in the stomach and intestine will be essential for advancing the feasibility of oral tracer administration.

Efficacy and in vitro pharmacological assessment of novel N-hydroxypyridinediones as hepatitis B virus ribonuclease H inhibitors

We previously reported N-hydroxypyridinedione (HPD) compounds with mid-nanomolar efficacy and selectivity indexes around 300 against hepatitis B virus (HBV) replication. However, they lack pharmacological evaluation. Here, we report in vitro anti-HBV efficacy, cytotoxicity, and pharmacological characterization of 29 novel HPDs within seven subgroups. The best two compounds had EC50s of 61 and 190 nM and selectivity indexes of 526 and 1,071. Compounds with one halogen on the major R group were most effective and compounds with large ether R groups were most cytotoxic. Compounds were not cytotoxic in primary human hepatocytes. All compounds were freely soluble in pHs reflecting plasma (7.4) and the gastrointestinal tract (5 and 6.5). Almost all highly soluble compounds were passively permeable at pH 5.0 and 7.4. Only 2 of 11 compounds tested were likely to be effluxed by p-glycoprotein. The most potent HPDs inhibited HBV replication over human ribonuclease H1 activity by 10-fold. Four of 19 compounds inhibited CYP2D6 >50%, but their CYP2D6 IC50s were >8× higher than their anti-HBV EC50. No compound substantially inhibited CYP3A4. Thirteen of 15 compounds had human microsomal half-lives >30 min with medium to low rates of intrinsic clearance. Eleven of 12 compounds bound plasma proteins by ≥80%; however, effects against HBV replication for only one would likely be physiologically relevant. These results identify two lead candidate HPDs with pharmacological characteristics resembling commercially available drugs that are suitable for in vivo pharmacological and efficacy studies.

Nanoparticle Interactions with the Blood Brain Barrier: Insights from Drosophila and Implications for Human Astrocyte Targeted Therapies

This review explores the intricate connections between Drosophila models and the human blood-brain barrier (BBB) with nanoparticle-based approaches for neurological treatment. Drosophila serves as a powerful model organism due to its evolutionary conservation of key biological processes, particularly in the context of the BBB, which is formed by glial cells that share structural and functional similarities with mammalian endothelial cells. Recent advancements in nanoparticle technology have highlighted their potential for effective drug delivery across the BBB, utilizing mechanisms such as passive diffusion, receptor-mediated transcytosis, and carrier-mediated transport. The ability to engineer nanoparticles with specific physicochemical properties-such as size, surface charge, and functionalization-enhances their targeting capabilities, particularly towards astrocytes, which play a crucial role in maintaining BBB integrity and responding to neuroinflammation. Insights gained from Drosophila studies have informed the design of personalized nanomedicine strategies aimed at treating neurodegenerative diseases, including Alzheimer's, Parkinson's disease etc. As research progresses, the integration of findings from Drosophila models with emerging humanized BBB systems will pave the way for innovative therapeutic approaches that improve drug delivery and patient outcomes in neurological disorders.

Ganoderma lucidum extract reverses multidrug resistance in breast cancer cells through inhibiting ATPase activity of the P-glycoprotein via MAPK/ERK signaling pathway

Breast cancer represents a persistent global health challenge, with multidrug resistance (MDR) posing a significant obstacle to effective treatment. In this study, we investigate the potential of Ganoderma lucidum extract (GLE) in reversing MDR in breast cancer and delve into the underlying mechanisms. We establish a robust in vitro 3D model of breast cancer with acquired MDR induced by paclitaxel. Utilizing the CCK-8 method, we assess the impact of GLE on cytotoxic drug sensitivity to determine its in vitro MDR reversal activity. Our results reveal that GLE enhances the toxicity of paclitaxel in breast cancer cells by inhibiting the ATPase activity of P-glycoprotein (P-gp) and increasing the intracellular and extracellular excretion of P-gp substrates, all without significantly altering P-gp protein expression. Additionally, GLE inhibits the phosphorylation of ERK1/2, suggesting that the enhanced sensitivity of breast cancer cells to paclitaxel by GLE is associated with the MAPK pathway. These findings indicate that GLE may inhibit P-gp-mediated drug efflux via the MAPK pathway, thus effectively overcoming paclitaxel resistance in breast cancer. This study provides valuable insights into the potential clinical applications of GLE in reversing multidrug resistance, offering hope for improved breast cancer treatment strategies.

Drug Screening of Flavonoids as Potential VEGF Inhibitors Through Computational Docking and Cell Models

Vascular endothelial growth factor (VEGF), also known as VEGF-A, has been linked to various diseases, such as wet age-related macular degeneration (wAMD) and cancer. Even though there are VEGF inhibitors that are currently commercially available in clinical applications, severe adverse effects have been associated with these treatments. There is still a need to develop novel VEGF-based therapeutics against these VEGF-related diseases. Here, we established a series of VEGF-based computational docking analyses and cell models, such as a wound healing assay in HaCaT cells and an evaluation of NF-κB performance in macrophages, to screen a large library of flavonoid-type phytochemicals. Three flavonoids, namely, farrerol, ononin and (-)-epicatechin, were shown to express binding affinities to VEGF protein and inhibit VEGF-mediated biological activities. The investigation evidently suggested that the three flavonoids above could be considered potential anti-VEGF agents for the following drug development against VEGF-mediated diseases.

Evaluation of the Alkaloids as Inhibitors of Human Acetylcholinesterase by Molecular Docking and ADME Prediction

BACKGROUND/AIM

Alzheimer's disease is a complex, incurable to date, multifactorial disease, which suggests the need for continued development of pharmacotherapy.

MATERIALS AND METHODS

A comprehensive literature search was conducted to identify known ligands with anticholinesterase activity, resulting in the discovery of over 100 alkaloids that are also available in the PubChem database. Subsequently, the ligands underwent molecular docking to evaluate their affinity for the target enzyme. The ligands with the greatest affinity were selected for ligand-based virtual screening.

RESULTS

Three potential compounds were identified for further investigation: ZINC000055042508, ZINC000096316348, and ZINC000067 446933. Computational models of absorption, distribution, metabolism, and excretion (ADME) properties prediction using SwissADME suggested that ZINC000055042508 and ZINC000067446933 can permeate the blood-brain barrier and exhibit non-substrate behavior with respect to P-glycoprotein. In contrast, the ProTox-III prediction indicated the potential for all three compounds to penetrate the blood-brain barrier.

CONCLUSION

These alkaloid derivatives warrant further investigation as potential acetylcholinesterase inhibitors for the treatment of Alzheimer's disease.

Antiparasitic Activity of Coumarin-Chalcone (3-Cinnamoyl-2H-Chromen-2-Ones) Hybrids

Coumarin-chalcone hybrids are promising compounds that could be used as lead structures in the fight against parasitic diseases. In this work, 16 hybrids of coumarin-chalcone (3-cinnamoyl-2H-chromen-2-ones) were synthesized, and their in vitro biological activity was evaluated against intracellular amastigotes of Leishmania braziliensis and Trypanosoma cruzi, as well as their cytotoxicity in the U-937 cell line. Compounds (E)-3-(3-(3-ethoxy-4-hydroxyphenyl)acryloyl)-7-methoxy-2H-chromen-2-one (H25) and (E)-7-(diethylamino)-3-(4-(methoxyphenyl)acryloyl)-2H-chromen-2-one (H12) showed the highest antileishmanial activity with EC50 values of 18.6 ± 3.5 and 25.6 ± 0.4 µM, respectively. In general, all 16 compounds exhibited moderate-to-high antitrypanosomal activity. The H25 hybrid also demonstrated the greatest antitrypanosomal activity, with an EC50 value of 13.2 ± 0.4 µM. Notably, the H25 hybrid displayed activity similar to that of benznidazole, which is known for its antiparasitic effects against T. cruzi. The results indicated that all compounds met the drug-like properties criteria. Taking into account the high antiparasitic activity of H25, a molecular docking study with the enzyme trypanothione reductase was performed. The substituent at C7 in the coumarinyl system is an important structural requirement for the antileishmanial and antitrypanosomal activities.

BH3-mimetics or DNA-damaging agents in combination with RG7388 overcome p53 mutation-induced resistance to MDM2 inhibition

The development of drug resistance reduces the efficacy of cancer therapy. Tumor cells can acquire resistance to MDM2 inhibitors, which are currently under clinical evaluation. We generated RG7388-resistant neuroblastoma cells, which became more proliferative and metabolically active and were less sensitive to DNA-damaging agents in vitro and in vivo, compared with wild-type cells. The resistance was associated with a mutation of the p53 protein (His193Arg). This mutation abated its transcriptional activity via destabilization of the tetrameric p53-DNA complex and was observed in many cancer types. Finally, we found that Cisplatin and various BH3-mimetics could enhance RG7388-mediated apoptosis in RG7388-resistant neuroblastoma cells, thereby partially overcoming resistance to MDM2 inhibition.

Isolation, Structure Elucidation, and Bioactivity Evaluation of Two Alkaloids From Piper chaba H. Stem: A Traditional Medicinal Spice and Its Chemico-Pharmacological Aspects

Bangladesh is endowed with an abundance of excellent medicinal plant resources. A well-known traditional medicinal plant Piper chaba H. from the Piperaceae family is rich in bioactive phytochemicals that have antidiarrheal, antimicrobial, analgesic, antioxidant, anticancer, and cytotoxic effects. This plant is locally known as "Chuijhal," and the stem is used as spices. In the current research program, the stems of the P. chaba plant were selected and its chemical and biological investigations such as antidiarrheal, antimicrobial, and analgesic effects were performed. Moreover, docking models were accomplished by exploiting PyRx-Virtual Screening software and implied that isolated compounds of P. chaba exert different pharmacological activity by inhibiting their targeted receptors. Phytochemical investigations revealed the isolation of Chingchengenamide A, a relatively rare alkaloid from the stems of P. chaba. Another alkaloid Chabamide I which is a piperine dimer was also isolated. Their structures were confirmed by comparing these compounds' spectral data (1H and 13C NMR) with their previously published spectral data. Antidiarrheal activity shows a percent reduction of diarrhea by 46.67% and 40%, respectively, for Chabamide I and Chingchengenamide A (at 20 mg/kg b.w.) compared with an 80% reduction by standard loperamide. Similarly, the percent reduction of writhing was 53.06% and 42.86%, respectively, for Chabamide I and Chingchengenamide A at similar doses compared with an 80% reduction by diclofenac sodium considered as standard. Both the alkaloids showed auspicious outcomes against test microorganisms during disk diffusion antimicrobial assay. Molecular docking and ADME/T analysis of the alkaloids also validate a potent pharmacological basis for the traditional utilization of P. chaba in treating diarrhea, pain, and microbial infection. These results emphasize the need to investigate P. chaba as a potential source of natural therapies for common health issues, laying the foundation for future research.

Investigating how HIV-1 antiretrovirals differentially behave as substrates and inhibitors of P-glycoprotein via molecular dynamics simulations

HIV-1 can rapidly infect the brain upon initial infection, establishing latent reservoirs that induce neuronal damage and/or death, resulting in HIV-Associated Neurocognitive Disorder. Though anti-HIV-1 antiretrovirals (ARVs) suppress viral load, the blood-brain barrier limits drug access to the brain, largely because of highly expressed efflux proteins like P-glycoprotein (P-gp). While no FDA-approved P-gp inhibitor currently exists, HIV-1 protease inhibitors show promise as partial P-gp inhibitors, potentially enhancing drug delivery to the brain. Herein, we employed docking and molecular dynamics simulations to elucidate key differences in P-gp's interactions with several antiretrovirals, including protease inhibitors, with known inhibitory or substrate-like behaviors towards P-gp. Our results led us to hypothesize new mechanistic details of small-molecule efflux by and inhibition of P-gp, where the "Lower Pocket" in P-gp's transmembrane domain serves as the primary initial site for small-molecule binding. Subsequently, this pocket merges with the more traditionally studied drug binding site-the "Upper Pocket"-thus funneling small-molecule drugs, such as ARVs, towards the Upper Pocket for efflux. Furthermore, our results reinforce the understanding that both binding energetics and changes in protein dynamics are crucial in discerning small molecules as non-substrates, substrates, or inhibitors of P-gp. Our findings indicate that interactions between P-gp and inhibitory ARVs induce bridging of transmembrane domain helices, impeding P-gp conformational changes and contributing to the inhibitory behavior of these ARVs. Overall, insights gained in this study could serve to guide the design of future P-gp-targeting therapeutics for a wide range of pathological conditions and diseases, including HIV-1.

Human Cytochrome P450 Cancer-Related Metabolic Activities and Gene Polymorphisms: A Review

BACKGROUND

Cytochromes P450 (CYPs) are heme-containing oxidoreductase enzymes with mono-oxygenase activity. Human CYPs catalyze the oxidation of a great variety of chemicals, including xenobiotics, steroid hormones, vitamins, bile acids, procarcinogens, and drugs.

FINDINGS

In our review article, we discuss recent data evidencing that the same CYP isoform can be involved in both bioactivation and detoxification reactions and convert the same substrate to different products. Conversely, different CYP isoforms can convert the same substrate, xenobiotic or procarcinogen, into either a more or less toxic product. These phenomena depend on the type of catalyzed reaction, substrate, tissue type, and biological species. Since the CYPs involved in bioactivation (CYP3A4, CYP1A1, CYP2D6, and CYP2C8) are primarily expressed in the liver, their metabolites can induce hepatotoxicity and hepatocarcinogenesis. Additionally, we discuss the role of drugs as CYP substrates, inducers, and inhibitors as well as the implication of nuclear receptors, efflux transporters, and drug-drug interactions in anticancer drug resistance. We highlight the molecular mechanisms underlying the development of hormone-sensitive cancers, including breast, ovarian, endometrial, and prostate cancers. Key players in these mechanisms are the 2,3- and 3,4-catechols of estrogens, which are formed by CYP1A1, CYP1A2, and CYP1B1. The catechols can also produce quinones, leading to the formation of toxic protein and DNA adducts that contribute to cancer progression. However, 2-hydroxy- and 4-hydroxy-estrogens and their O-methylated derivatives along with conjugated metabolites play cancer-protective roles. CYP17A1 and CYP11A1, which are involved in the biosynthesis of testosterone precursors, contribute to prostate cancer, whereas conversion of testosterone to 5α-dihydrotestosterone as well as sustained activation and mutation of the androgen receptor are implicated in metastatic castration-resistant prostate cancer (CRPC). CYP enzymatic activities are influenced by CYP gene polymorphisms, although a significant portion of them have no effects. However, CYP polymorphisms can determine poor, intermediate, rapid, and ultrarapid metabolizer genotypes, which can affect cancer and drug susceptibility. Despite limited statistically significant data, associations between CYP polymorphisms and cancer risk, tumor size, and metastatic status among various populations have been demonstrated.

CONCLUSIONS

The metabolic diversity and dual character of biological effects of CYPs underlie their implications in, preliminarily, hormone-sensitive cancers. Variations in CYP activities and CYP gene polymorphisms are implicated in the interindividual variability in cancer and drug susceptibility. The development of CYP inhibitors provides options for personalized anticancer therapy.

lncRNAs: New players of cancer drug resistance via targeting ABC transporters

Cancer drug resistance poses a significant obstacle to successful chemotherapy, primarily driven by the activity of ATP-binding cassette (ABC) transporters, which actively efflux chemotherapeutic agents from cancer cells, reducing their intracellular concentrations and therapeutic efficacy. Recent studies have highlighted the pivotal role of long noncoding RNAs (lncRNAs) in regulating this resistance, positioning them as crucial modulators of ABC transporter function. lncRNAs, once considered transcriptional noise, are now recognized for their complex regulatory capabilities at various cellular levels, including chromatin modification, transcription, and post-transcriptional processing. This review synthesizes current research demonstrating how lncRNAs influence cancer drug resistance by modulating the expression and activity of ABC transporters. lncRNAs can act as molecular sponges, sequestering microRNAs that would otherwise downregulate ABC transporter genes. Additionally, they can alter the epigenetic landscape of these genes, affecting their transcriptional activity. Mechanistic insights reveal that lncRNAs contribute to the activity of ABC transporters, thereby altering the efflux of chemotherapeutic drugs and promoting drug resistance. Understanding these interactions provides a new perspective on the molecular basis of chemoresistance, emphasizing the regulatory network of lncRNAs and ABC transporters. This knowledge not only deepens our understanding of the biological mechanisms underlying drug resistance but also suggests novel therapeutic strategies. In conclusion, the intricate interplay between lncRNAs and ABC transporters is crucial for developing innovative solutions to combat cancer drug resistance, underscoring the importance of continued research in this field.

Autocrine Motility Factor and Its Peptide Derivative Inhibit Triple-Negative Breast Cancer by Regulating Wound Repair, Survival, and Drug Efflux

Triple-negative breast cancer (TNBC) presents a significant challenge in oncology due to its aggressive nature and limited targeted therapeutic options. This study explores the potential of autocrine motility factor (AMF) and an AMF-derived peptide as novel treatments for TNBC. AMF, primarily secreted by neoplastic cells, plays a crucial role in cancer cell motility, metastasis, and proliferation. The research demonstrates that AMF and its derived peptide inhibit TNBC cell proliferation by modulating cellular migration, redox homeostasis, apoptotic pathways, and drug efflux mechanisms. Dose-dependent antiproliferative effects were observed across three TNBC cell lines, with higher concentrations impairing cellular migration. Mechanistic studies revealed decreased glucose-6-phosphate dehydrogenase expression and elevated reactive oxygen species production, suggesting redox imbalance as a primary mediator of apoptosis. Combination studies with conventional therapeutics showed near-complete eradication of resistant TNBC cells. The observed reduction in p53 levels and increased intranuclear doxorubicin accumulation highlight the AMF/AMF peptide's potential as multidrug resistance modulators. This study underscores the promise of using AMF/AMF peptide as a novel therapeutic approach for TNBC, addressing current treatment limitations and warranting further investigation.

Glyphosate and aminomethylphosphonic acid impact on redox status and biotransformation in fish and the mitigating effects of diet supplementation

Fish reared under seminatural conditions can be challenged by exposure to herbicides. Farming facilities relying on the surrounding area's water quality can be affected by glyphosate and aminomethylphosphonic acid (AMPA) contamination. This review summarizes findings on how glyphosate and AMPA in the amounts registered in surface waterbodies affect redox status and biotransformation in fish and covers the aspect of diet supplementation for oxidative stress relief. Environmentally relevant concentrations of glyphosate and AMPA can alter the transcription and catalytic activities of antioxidant enzymes, decrease the content of reduced glutathione, and increase the accumulation of lipid peroxidation products, all of which are signs of a redox imbalance. Glyphosate has been shown to affect complex I in the mitochondrial respiratory chain and dysregulate iron transport-related genes, causing redox disturbance. Relatively high but environmentally realistic glyphosate concentrations can initiate the induction of cytochrome P450 biotransformation enzymes, alter the regulation of ABC exporters, and cause the inhibition of the redox-sensitive Nrf2 signaling pathway. Studies on reducing herbicide toxicity through dietary supplementation are a promising area of research. Natural functional supplements have been proven to have great potential for mitigating glyphosate-induced oxidative stress and thereby improving fish health, which in turn means maintaining productivity in fish farms that use natural water. However, data on the effects of AMPA on fish are scarce, and studies on the alleviation of its toxicity in fish are lacking. Considering the variety of AMPA contamination routes, one cannot underestimate the need for further research.

Synthesis, Preclinical Toxicity, and Biodistribution of [18F]AVT-011 to Assess the P-Glycoprotein Function

Introduction: Many studies have reported the role of P-glycoprotein (Pgp) in chemoresistance in various pathological conditions such as cancer and neurodegenerative diseases, such as Alzheimer's. In this study, we are reporting the high-performance liquid chromatography (HPLC)-based purification of fluorine-18 [18F]AVT-011 and its preclinical evaluation. Methods: AVT-011 was labeled with 18F using the nucleophilic substitution method by heating the reaction mixture at 110°C for 10 min, followed by purification using preparative HPLC and C18ec cartridge. The in vitro cell uptake study was carried out in U87 cells with and without an inhibitor. The preclinical toxicity was carried out in CD1 mice in three groups, including control, AVT-011 treated, and [18F]AVT-011 treated. The biodistribution study was done in CD1 mice (n = 12) after intravenous injection of 4-6 MBq [18F]AVT-011, and mice were sacrificed at various time intervals. A dose of 3.7 ± 0.7 MBq of [18F]AVT-011 was injected intravenously in the healthy Swiss albino mice, and the whole-body micro-positron emission tomography was acquired at 0-, 30-, 60-, and 120-min postinjection. Results: The radiochemical purity of [18F]AVT-011 was 97 ± 1.5% as evaluated by radio-HPLC with a yield of 14 ± 2% and was stable up to 95% under in vitro conditions in blood and in vivo conditions up to 4 h. The in vitro cell uptake study showed a significant difference in control (27.4 ± 2.1%) and blocked U987 cells (73.2 ± 3.2%) after incubation of 120 min. The tissue distribution in mice showed the highest uptake in the liver (17.3 ± 2.4%), kidneys (16.6 ± 3.1%), lungs (10.4 ± 2.9%), and spleen (5.6 ± 0.8%) at 15 min, and the activity was washed out with time. The radioactivity cleared through the hepatorenal pathway. The animal imaging study also demonstrates a similar biodistribution pattern. Conclusions: [18F]AVT-011 showed higher specific activity than the cartridge-based method but showed similar biological activity.

Plant-Based Products Originating from Serbia That Affect P-glycoprotein Activity

Our review paper evaluates the impact of plant-based products, primarily derived from plants from Serbia, on P-glycoprotein (P-gp) activity and their potential in modulating drug resistance in cancer therapy. We focus on the role and regulation of P-gp in cellular physiology and its significance in addressing multidrug resistance in cancer therapy. Additionally, we discuss the modulation of P-gp activity by 55 natural product drugs, including derivatives for some of them, based on our team's research findings since 2011. Specifically, we prospect into sesquiterpenoids from the genera Artemisia, Curcuma, Ferula, Inula, Petasites, and Celastrus; diterpenoids from the genera Salvia and Euphorbia; chalcones from the genera Piper, Glycyrrhiza, Cullen, Artemisia, and Humulus; riccardins from the genera Lunularia, Monoclea, Dumortiera, Plagiochila, and Primula; and diarylheptanoids from the genera Alnus and Curcuma. Through comprehensive analysis, we aim to highlight the potential of natural products mainly identified in plants from Serbia in influencing P-gp activity and overcoming drug resistance in cancer therapy, while also providing insights into future perspectives in this field.

Comprehensive insights into herbal P-glycoprotein inhibitors and nanoformulations for improving anti-retroviral therapy efficacy

The worldwide HIV cases were 39.0 million (33.1-45.7 million) in 2022. Due to genetic variations, HIV-1 is more easily transmitted than HIV-2 and favours CD4 + T cells and macrophages, producing AIDS. Conventional HIV drug therapy has many drawbacks, including adherence issues leading to resistance, side effects that lower life quality, drug interactions, high costs limiting global access, inability to eliminate viral reservoirs, chronicity requiring lifelong treatment, emerging toxicities, and a focus on managing infections. Conventional dosage forms have bioavailability issues due to intestinal P-glycoprotein (P-gp) efflux, which can reduce anti-retroviral drug efficacy and lead to resistance. Use of phyto-constituents with P-gp regulating actions has great benefits for semi-synthetic modification to create formulations with greater bioavailability and reduced toxicity, which improves drug effectiveness. Lipid-based nanocarriers, solid lipid nanoparticles, nanostructured lipid carriers, polymer-based nanocarriers, and inorganic nanoparticles may inhibit P-gp efflux. Employing potent P-gp inhibitors within nanocarriers as a Trojan horse approach can enhance the intracellular accumulation of anti-retroviral drugs (ARDs), which are substrates for efflux transporters. This technique increases oral bioavailability and offers lower-dose options, boosting HIV patient compliance and lowering costs. Molecular docking of the inhibitor with P-gp may anticipate optimum binding and function, allowing drug efflux to be minimised.

P-glycoprotein inhibitors as an adjunct therapy for TB

The primary challenge in TB treatment is the emergence of multidrug-resistant TB (MDR-TB). One of the major factors responsible for MDR is the upregulation of efflux pumps. Permeation-glycoprotein (P-gp), an efflux pump, hinders the bioavailability of the administered drugs inside the infected cells. Simultaneously, angiogenesis, the formation of new blood vessels, contributes to drug delivery complexities. TB infection triggers a cascade of events that upregulates the expression of angiogenic factors and P-gp. The combined action of P-gp and angiogenesis foster the emergence of MDR-TB. Understanding these mechanisms is pivotal for developing targeted interventions to overcome MDR in TB. P-gp inhibitors, such as verapamil, and anti-angiogenic drugs, including bevacizumab, have shown improvement in TB drug delivery to granuloma. In this review, we discuss the potential of P-gp inhibitors as an adjunct therapy to shorten TB treatment.

Cyanine dyes in the mitochondria-targeting photodynamic and photothermal therapy

Mitochondrial dysregulation plays a significant role in the carcinogenesis. On the other hand, its destabilization strongly represses the viability and metastatic potential of cancer cells. Photodynamic and photothermal therapies (PDT and PTT) target mitochondria effectively, providing innovative and non-invasive anticancer therapeutic modalities. Cyanine dyes, with strong mitochondrial selectivity, show significant potential in enhancing PDT and PTT. The potential and limitations of cyanine dyes for mitochondrial PDT and PTT are discussed, along with their applications in combination therapies, theranostic techniques, and optimal delivery systems. Additionally, novel approaches for sonodynamic therapy using photoactive cyanine dyes are presented, highlighting advances in cancer treatment.

Effect of carvedilol on pharmacokinetics of sofosbuvir and its metabolite GS-331007: role of P-glycoprotein

Sofosbuvir (SOF) is a P-glycoprotein (P-gp) substrate, and carvedilol (CAR) is an inhibitor of P-gp, suggesting that it may affect the oral pharmacokinetics and safety of SOF. The current study investigated the pharmacokinetic interaction of CAR with SOF and its metabolite, GS-331007, and the possible consequent toxicities in rats. To assess the pharmacokinetics of SOF and GS-331007, rats were divided into three groups; all received a single oral dose of SOF preceded with saline (SAL), verapamil (VER) as a standard P-gp inhibitor, or CAR, respectively. The serosal, plasma, and hepatic tissue contents of SOF and GS-331007 were assessed using LC-MS/MS. Renal and hepatic toxicities were assessed using biochemical and histopathological tests. Serosal and plasma concentrations of SOF and GS-331007 were increased in the presence of CAR, suggesting a significant inhibitory effect of CAR on intestinal P-gp. Simultaneously, the pharmacokinetic profile of SOF showed a significant increase in the Cmax, AUC(0-t), AUC (0-∞), t1/2, and a reduction in its apparent oral clearance. While the pharmacokinetic profile of GS-331007 was not significantly affected. However, this notable elevation in drug oral bioavailability was corroborated by a significant alteration in renal functions. Hence, further clinical investigations are recommended to ensure the safety and dosing of CAR/SOF combination.

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.

Identification of DPP-IV inhibitory peptides derived from buffalo colostrum: Mining through bioinformatics, in silico and in vitro approaches

Bioactive peptides derived from foods provide physiological health benefits beyond nutrition. This study focused on profiling small peptide inhibitors against two key serine proteases, dipeptidyl peptidase-IV (DPP-IV) and prolyl oligopeptidase (POP). DPP-IV is a well-known protein involved in diverse pathways regulating inflammation, renal, cardiovascular physiology, and glucose homeostasis. POP is yet another key target protein for neurodegenerative disorders. The study evaluated peptide libraries of buffalo colostrum whey and fat globule membrane proteins derived from pepsin and pepsin-pancreatin digestion through in silico web tools and structure-based analysis by molecular docking and binding free-energy estimation, followed by in vitro assay for DPP-IV inhibition for the lead peptides. The bioinformatic study indicated 49 peptides presented motifs with DPP-IV inhibition while 5 peptides with sequences for POP inhibition. In the molecular docking interactions study, 22 peptides interacted with active site residues of DPP-IV and 3 peptides with that of POP. The synthesized peptides, SFVSEVPEL and LTFQHNF inhibited DPP-IV in vitro with an IC50 of 193.5 μM and 1.782 mM, respectively. The study revealed the key residues for inhibition of DPP-IV and POP thus affirming the DPP-IV inhibitory potential of milk-derived peptides.

Molecular docking of antidiabetic molecules of libas (Spondias pinnata) fruit and prediction of their pharmacokinetic properties

Diabetes mellitus is one of the chronic metabolic disorders that affects more than 16 million Filipinos. Proper education, medical intervention, and a good lifestyle can help individuals control and manage this disease. Spondias pinnata is one of the underutilized crops in the Philippines that is well-known for its satisfactory flavor and medicinal properties, including its antidiabetic activity. The quest for a natural and effective drug to manage diseases is a continuous work in progress. Drug discovery and design is a tedious and expensive process. Computer-aided drug design guides the design and makes the process more efficient and less costly. Molecular docking was used to determine the potential antidiabetic compounds from the 48 reported compounds found in S. pinnata fruit. Seven compounds namely squalene (-9.1 kcal/mol), rutin (-9 kcal/mol), catechin (-8.7 kcal/mol), quercetin (-8.5 kcal/mol), tocopherol (-8.4 kcal/mol), myricetin (-8.4 kcal/mol), and ellagic acid (-8.3 kcal/mol) showed binding affinities comparable to those of pioglitazone, a standard drug, with peroxisome proliferator-activated receptor gamma (PPARγ). Tocopherol and catechin showed good ADMET properties. Among the two compounds, catechin passed the four filters for drug-likeness. Thus, catechin could be a potential compound for the development of antidiabetic drugs.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40203-024-00230-3.

Fetus Exposure to Drugs and Chemicals: A Holistic Overview on the Assessment of Their Transport and Metabolism across the Human Placental Barrier

BACKGROUND

The placenta exerts a crucial role in fetus growth and development during gestation, protecting the fetus from maternal drugs and chemical exposure. However, diverse drugs and chemicals (xenobiotics) can penetrate the maternal placental barrier, leading to deleterious, adverse effects concerning fetus health. Moreover, placental enzymes can metabolize drugs and chemicals into more toxic compounds for the fetus. Thus, evaluating the molecular mechanisms through which drugs and chemicals transfer and undergo metabolism across the placental barrier is of vital importance. In this aspect, this comprehensive literature review aims to provide a holistic approach by critically summarizing and scrutinizing the potential molecular processes and mechanisms governing drugs and chemical transfer and metabolism across the placental barrier, which may lead to fetotoxicity effects, as well as analyzing the currently available experimental methodologies used to assess xenobiotics placental transfer and metabolism.

METHODS

A comprehensive and in-depth literature review was conducted in the most accurate scientific databases such as PubMed, Scopus, and Web of Science by using relevant and effective keywords related to xenobiotic placental transfer and metabolism, retrieving 8830 published articles until 5 February 2024. After applying several strict exclusion and inclusion criteria, a final number of 148 relevant published articles were included.

RESULTS

During pregnancy, several drugs and chemicals can be transferred from the mother to the fetus across the placental barrier by either passive diffusion or through placental transporters, resulting in fetus exposure and potential fetotoxicity effects. Some drugs and chemicals also appear to be metabolized across the placental barrier, leading to more toxic products for both the mother and the fetus. At present, there is increasing research development of diverse experimental methodologies to determine the potential molecular processes and mechanisms of drug and chemical placental transfer and metabolism. All the currently available methodologies have specific strengths and limitations, highlighting the strong demand to utilize an efficient combination of them to obtain reliable evidence concerning drug and chemical transfer and metabolism across the placental barrier. To derive the most consistent and safe evidence, in vitro studies, ex vivo perfusion methods, and in vivo animal and human studies can be applied together with the final aim to minimize potential fetotoxicity effects.

CONCLUSIONS

Research is being increasingly carried out to obtain an accurate and safe evaluation of drug and chemical transport and metabolism across the placental barrier, applying a combination of advanced techniques to avoid potential fetotoxic effects. The improvement of the currently available techniques and the development of novel experimental protocols and methodologies are of major importance to protect both the mother and the fetus from xenobiotic exposure, as well as to minimize potential fetotoxicity effects.

Tumor glucose metabolism and the T cell glycocalyx: implication for T cell function

The T cell is an immune cell subset highly effective in eliminating cancer cells. Cancer immunotherapy empowers T cells and occupies a solid position in cancer treatment. The response rate, however, remains relatively low (<30%). The efficacy of immunotherapy is highly dependent on T cell infiltration into the tumor microenvironment (TME) and the ability of these infiltrated T cells to sustain their function within the TME. A better understanding of the inhibitory impact of the TME on T cells is crucial to improve cancer immunotherapy. Tumor cells are well described for their switch into aerobic glycolysis (Warburg effect), resulting in high glucose consumption and a metabolically distinct TME. Conversely, glycosylation, a predominant posttranslational modification of proteins, also relies on glucose molecules. Proper glycosylation of T cell receptors influences the immunological synapse between T cells and tumor cells, thereby affecting T cell effector functions including their cytolytic and cytostatic activities. This review delves into the complex interplay between tumor glucose metabolism and the glycocalyx of T cells, shedding light on how the TME can induce alterations in the T cell glycocalyx, which can subsequently influence the T cell's ability to target and eliminate tumor cells.

Cellular and Mitochondrial Toxicity of Tolcapone, Entacapone, and New Nitrocatechol Derivatives

Nitrocatechols are the standard pharmacophore to develop potent tight-binding inhibitors of catechol O-methyltransferase (COMT), which can be used as coadjuvant drugs to manage Parkinson's disease. Tolcapone is the most potent drug of this class, but it has raised safety concerns due to its potential to induce liver damage. Tolcapone-induced hepatotoxicity has been attributed to the nitrocatechol moiety; however, other nitrocatechol-based COMT inhibitors, such as entacapone, are safe and do not damage the liver. There is a knowledge gap concerning which mechanisms and chemical properties govern the toxicity of nitrocatechol-based COMT inhibitors. Using a vast array of cell-based assays, we found that tolcapone-induced toxicity is caused by direct interference with mitochondria that does not depend on bioactivation by P450. Our findings also suggest that (a) lipophilicity is a key property in the toxic potential of nitrocatechols; (b) the presence of a carbonyl group directly attached to the nitrocatechol ring seems to increase the reactivity of the molecule, and (c) the presence of cyano moiety in double bond stabilizes the reactivity decreasing the cytotoxicity. Altogether, the fine balance between lipophilicity and the chemical nature of the C1 substituents of the nitrocatechol ring may explain the difference in the toxicological behavior observed between tolcapone and entacapone.

In-vitro and in-vivo assessment of nirmatrelvir penetration into CSF, central nervous system cells, tissues, and peripheral blood mononuclear cells

Three years after SARS-CoV-2 emerged as a global infectious threat, the virus has become endemic. The neurological complications such as depression, anxiety, and other CNS complications after COVID-19 disease are increasing. The brain, and CSF have been shown as viral reservoirs for SARS-CoV-2, yielding a potential hypothesis for CNS effects. Thus, we investigated the CNS pharmacology of orally dosed nirmatrelvir/ritonavir (NMR/RTV). Using both an in vitro and an in vivo rodent model, we investigated CNS penetration and potential pharmacodynamic activity of NMR. Through pharmacokinetic modeling, we estimated the median CSF penetration of NMR to be low at 18.11% of plasma with very low accumulation in rodent brain tissue. Based on the multiples of the 90% maximal effective concentration (EC90) for SARS-CoV-2, NMR concentrations in the CSF and brain do not achieve an exposure level similar to that of plasma. A median of only 16% of all the predicted CSF concentrations in rats were > 3xEC90 (unadjusted for protein binding). This may have implications for viral persistence and neurologic post-acute sequelae of COVID-19 if increased NMR penetration in the CNS leads to decreased CNS viral loads and decreased CNS inflammation.

Mechanism of tacrolimus in the treatment of lupus nephritis

Systemic lupus erythematosus (SLE) is a complex autoimmune disorder, with more than half of the patients developing lupus nephritis (LN), which significantly contributes to chronic kidney disease (CKD) and end-stage renal disease (ESRD). The treatment of lupus nephritis has always been challenging. Tacrolimus (TAC), an effective immunosuppressant, has been increasingly used in the treatment of LN in recent years. This review aims to explore the mechanisms of action of tacrolimus in treating LN. Firstly, we briefly introduce the pharmacological properties of tacrolimus, including its role as a calcineurin (CaN) inhibitor, exerting immunosuppressive effects by inhibiting T cell activation and cytokine production. Subsequently, we focus on various other immunomodulatory mechanisms of tacrolimus in LN therapy, including its effects on T cells, B cells, and immune cells in kidney. Particularly, we emphasize tacrolimus' regulatory effect on inflammatory mediators and its importance in modulating the Th1/Th2 and Th17/Treg balance. Additionally, we review its effects on actin cytoskeleton, angiotensin II (Ang II)-specific vascular contraction, and P-glycoprotein activity, summarizing its impacts on non-immune mechanisms. Finally, we summarize the efficacy and safety of tacrolimus in clinical studies and trials. Although some studies have shown significant efficacy of tacrolimus in treating LN, its safety remains a challenge. We outline the potential adverse reactions of long-term tacrolimus use and provide suggestions on effectively monitoring and managing these adverse reactions in clinical practice. In general, tacrolimus, as a novel immunosuppressant, holds promising prospects for treating LN. Of course, further research is needed to better understand its therapeutic mechanisms and ensure its safety and efficacy in clinical practice.

Multidrug resistance transporters P-gp and BCRP limit the efficacy of ATR inhibitor ceralasertib in cancer cells

The therapeutic effect of chemotherapy and targeted therapy are known to be limited by drug resistance. Substantial evidence has shown that ATP-binding cassette (ABC) transporters P-gp and BCRP are significant contributors to multidrug resistance (MDR) in cancer cells. In this study, we demonstrated that a clinical-staged ATR inhibitor ceralasertib is susceptible to P-gp and BCRP-mediated MDR. The drug resistant cancer cells were less sensitive to ceralasertib compared to the parental cells. Moreover, ceralasertib resistance can be reversed by inhibiting the drug efflux activity of P-gp and BCRP. Interestingly, ceralasertib was able to downregulate the level of P-gp but not BCRP, suggesting a potential regulation between ATR signaling and P-gp expression. Furthermore, computational docking analysis predicted high affinities between ceralasertib and the drug-binding sites of P-gp and BCRP. In summary, overexpression of P-gp and BCRP are sufficient to confer cancer cells resistance to ceralasertib, underscoring their role as biomarkers for therapeutic efficacy.

Deciphering the functional role of clinical mutations in ABCB1, ABCC1, and ABCG2 ABC transporters in endometrial cancer

ATP-binding cassette transporters represent a superfamily of dynamic membrane-based proteins with diverse yet common functions such as use of ATP hydrolysis to efflux substrates across cellular membranes. Three major transporters-P-glycoprotein (P-gp or ABCB1), multidrug resistance protein 1 (MRP1 or ABCC1), and breast cancer resistance protein (BCRP or ABCG2) are notoriously involved in therapy resistance in cancer patients. Despite exhaustive individual characterizations of each of these transporters, there is a lack of understanding in terms of the functional role of mutations in substrate binding and efflux, leading to drug resistance. We analyzed clinical variations reported in endometrial cancers for these transporters. For ABCB1, the majority of key mutations were present in the membrane-facing region, followed by the drug transport channel and ATP-binding regions. Similarly, for ABCG2, the majority of key mutations were located in the membrane-facing region, followed by the ATP-binding region and drug transport channel, thus highlighting the importance of membrane-mediated drug recruitment and efflux in ABCB1 and ABCG2. On the other hand, for ABCC1, the majority of key mutations were present in the inactive nucleotide-binding domain, followed by the drug transport channel and membrane-facing regions, highlighting the importance of the inactive nucleotide-binding domain in facilitating indirect drug efflux in ABCC1. The identified key mutations in endometrial cancer and mapped common mutations present across different types of cancers in ABCB1, ABCC1, and ABCG2 will facilitate the design and discovery of inhibitors targeting unexplored structural regions of these transporters and re-engineering of these transporters to tackle chemoresistance.

Ligand- and Structure-Based Virtual Screening Identifies New Inhibitors of the Interaction of the SARS-CoV-2 Spike Protein with the ACE2 Host Receptor

The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is a fast-spreading viral pathogen and poses a serious threat to human health. New SARS-CoV-2 variants have been arising worldwide; therefore, is necessary to explore more therapeutic options. The interaction of the viral spike (S) protein with the angiotensin-converting enzyme 2 (ACE2) host receptor is an attractive drug target to prevent the infection via the inhibition of virus cell entry. In this study, Ligand- and Structure-Based Virtual Screening (LBVS and SBVS) was performed to propose potential inhibitors capable of blocking the S receptor-binding domain (RBD) and ACE2 interaction. The best five lead compounds were confirmed as inhibitors through ELISA-based enzyme assays. The docking studies and molecular dynamic (MD) simulations of the selected compounds maintained the molecular interaction and stability (RMSD fluctuations less than 5 Å) with key residues of the S protein. The compounds DRI-1, DRI-2, DRI-3, DRI-4, and DRI-5 efficiently block the interaction between the SARS-CoV-2 spike protein and receptor ACE2 (from 69.90 to 99.65% of inhibition) at 50 µM. The most potent inhibitors were DRI-2 (IC50 = 8.8 µM) and DRI-3 (IC50 = 2.1 µM) and have an acceptable profile of cytotoxicity (CC50 > 90 µM). Therefore, these compounds could be good candidates for further SARS-CoV-2 preclinical experiments.

Exploring the potential of P-glycoprotein inhibitors in the targeted delivery of anti-cancer drugs: A comprehensive review

Due to the high prevalence of cancer, progress in the management of cancer is the need of the hour. Most cancer patients develop chemotherapeutic drug resistance, and many remain insidious due to overexpression of Multidrug Resistance Protein 1 (MDR1), also known as Permeability-glycoprotein (P-gp) or ABCB1 transporter (ATP-binding cassette subfamily B member 1). P-gp, a transmembrane protein that protects vital organs from outside chemicals, expels medications from malignant cells. The blood-brain barrier (BBB), gastrointestinal tract (GIT), kidneys, liver, pancreas, and cancer cells overexpress P-gp on their apical surfaces, making treatment inefficient and resistant. Compounds that compete with anticancer medicines for transportation or directly inhibit P-gp may overcome biological barriers. Developing nanotechnology-based formulations may help overcome P-gp-mediated efflux and improve bioavailability and cell chemotherapeutic agent accumulation. Nanocarriers transport pharmaceuticals via receptor-mediated endocytosis, unlike passive diffusion, which bypasses ABCB1. Anticancer drugs and P-gp inhibitors in nanocarriers may synergistically increase drug accumulation and chemotherapeutic agent toxicity. The projection of desirable binding and effect may be procured initially by molecular docking of the inhibitor with P-gp, enabling the reduction of preliminary trials in formulation development. Here, P-gp-mediated efflux and several possible outcomes to overcome the problems associated with currently prevalent cancer treatments are highlighted.

C9ORF72 patient-derived endothelial cells drive blood-brain barrier disruption and contribute to neurotoxicity

The blood-brain barrier (BBB) serves as a highly intricate and dynamic interface connecting the brain and the bloodstream, playing a vital role in maintaining brain homeostasis. BBB dysfunction has been associated with multiple neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS); however, the role of the BBB in neurodegeneration is understudied. We developed an ALS patient-derived model of the BBB by using cells derived from 5 patient donors carrying C9ORF72 mutations. Brain microvascular endothelial-like cells (BMEC-like cells) derived from C9ORF72-ALS patients showed altered gene expression, compromised barrier integrity, and increased P-glycoprotein transporter activity. In addition, mitochondrial metabolic tests demonstrated that C9ORF72-ALS BMECs display a significant decrease in basal glycolysis accompanied by increased basal and ATP-linked respiration. Moreover, our study reveals that C9-ALS derived astrocytes can further affect BMECs function and affect the expression of the glucose transporter Glut-1. Finally, C9ORF72 patient-derived BMECs form leaky barriers through a cell-autonomous mechanism and have neurotoxic properties towards motor neurons.

Activity prediction, structure-based drug design, molecular docking, and pharmacokinetic studies of 1,4-dihydropyridines derivatives as α-amylase inhibitors

Objectives

Diabetes places a substantial economic burden on countries worldwide. The costs associated with diabetes management, including healthcare services, medications, monitoring equipment, and productivity losses, are substantial. The International Diabetes Federation has estimated that global healthcare expenditures associated with diabetes and its complications exceed hundreds of billions of dollars annually. Therefore, a critical need exists to develop drugs that are highly effective, affordable, and easily accessible to society.

Methods

This study explored the structural modification of 1,4-DHP derivatives to identify specific α-amylase inhibitors, with the aim of developing more effective and accessible drugs for diabetes. We evaluated the activity and binding ability of the designed compounds. In addition, we performed drug-likeness and pharmacokinetic studies on the modified compounds.

Results

Equation (1) had the highest accuracy, on the basis of internal and external assessment parameters, including R2int = 0.852, R2adj = 0.803, Q2cv = 0.731, and R2ext = 0.884. Moreover, the five potent analogs identified through structure-based drug design demonstrated a more favorable interaction than observed for the template or acarbose. Additionally, comprehensive studies on the drug-like properties and pharmacokinetics of the designed compounds supported their oral safety and favorable pharmacokinetic profiles.

Conclusions

The designed analogs show promise for developing new hypoglycemic agents. Their positive attributes and performance suggest that they may potentially serve as candidates for further research in improving treatments for high blood sugar-associated conditions.

Structural Basis for Oxidized Glutathione Recognition by the Yeast Cadmium Factor 1

Transporters from the ABCC family have an essential role in detoxifying electrophilic compounds including metals, drugs, and lipids, often through conjugation with glutathione complexes. The Yeast Cadmium Factor 1 (Ycf1) transports glutathione alone as well as glutathione conjugated to toxic heavy metals including Cd2+, Hg2+, and As3+. To understand the complicated selectivity and promiscuity of heavy metal substrate binding, we determined the cryo-EM structure of Ycf1 bound to the substrate, oxidized glutathione. We systematically tested binding determinants with cellular survival assays against cadmium to determine how the substrate site accommodates different-sized metal complexes. We identify a "flex-pocket" for substrate binding that binds glutathione complexes asymmetrically and flexes to accommodate different size complexes.

Evaluating the Therapeutic Potential of Curcumin and Synthetic Derivatives: A Computational Approach to Anti-Obesity Treatments

Natural compounds such as curcumin, a polyphenolic compound derived from the rhizome of turmeric, have gathered remarkable scientific interest due to their diverse metabolic benefits including anti-obesity potential. However, curcumin faces challenges stemming from its unfavorable pharmacokinetic profile. To address this issue, synthetic curcumin derivatives aimed at enhancing the biological efficacy of curcumin have previously been developed. In silico modelling techniques have gained significant recognition in screening synthetic compounds as drug candidates. Therefore, the primary objective of this study was to assess the pharmacokinetic and pharmacodynamic characteristics of three synthetic derivatives of curcumin. This evaluation was conducted in comparison to curcumin, with a specific emphasis on examining their impact on adipogenesis, inflammation, and lipid metabolism as potential therapeutic targets of obesity mechanisms. In this study, predictive toxicity screening confirmed the safety of curcumin, with the curcumin derivatives demonstrating a safe profile based on their LD50 values. The synthetic curcumin derivative 1A8 exhibited inactivity across all selected toxicity endpoints. Furthermore, these compounds were deemed viable candidate drugs as they adhered to Lipinski's rules and exhibited favorable metabolic profiles. Molecular docking studies revealed that both curcumin and its synthetic derivatives exhibited favorable binding scores, whilst molecular dynamic simulations showed stable binding with peroxisome proliferator-activated receptor gamma (PPARγ), csyclooxygenase-2 (COX2), and fatty acid synthase (FAS) proteins. The binding free energy calculations indicated that curcumin displayed potential as a strong regulator of PPARγ (-60.2 ± 0.4 kcal/mol) and FAS (-37.9 ± 0.3 kcal/mol), whereas 1A8 demonstrated robust binding affinity with COX2 (-64.9 ± 0.2 kcal/mol). In conclusion, the results from this study suggest that the three synthetic curcumin derivatives have similar molecular interactions to curcumin with selected biological targets. However, in vitro and in vivo experimental studies are recommended to validate these findings.

Evaluation of Antitumor Activity of Xanthones Conjugated with Amino Acids

Cancer is a complex disease characterized by several alterations, which confer, to the cells, the capacity to proliferate uncontrollably and to resist cellular death. Multiresistance to conventional chemotherapy drugs is often the cause of treatment failure; thus, the search for natural products or their derivatives with therapeutic action is essential. Chiral derivatives of xanthones (CDXs) have shown potential inhibitory activity against the growth of some human tumor cell lines. This work reports the screening of a library of CDXs, through viability assays, in different cancer cell lines: A375-C5, MCF-7, NCI-H460, and HCT-15. CDXs' effect was analyzed based on several parameters of cancer cells, and it was also verified if these compounds were substrates of glycoprotein-P (Pgp), one of the main mechanisms of resistance in cancer therapy. Pgp expression was evaluated in all cell lines, but no expression was observed, except for HCT-15. Also, when a humanized yeast expressing the human gene MDR1 was used, no conclusions could be drawn about CDXs as Pgp substrates. The selected CDXs did not induce significant differences in the metabolic parameters analyzed. These results show that some CDXs present promising antitumor activity, but other mechanisms should be triggered by these compounds.

Regulation of P-Glycoprotein during Oxidative Stress

P-glycoprotein (Pgp, ABCB1, MDR1) is an efflux transporter protein that removes molecules from the cells (outflow) into the extracellular space. Pgp plays an important role in pharmacokinetics, ensuring the absorption, distribution, and excretion of drugs and its substrates, as well as in the transport of endogenous molecules (steroid and thyroid hormones). It also contributes to tumor cell resistance to chemotherapy. In this review, we summarize the mechanisms of Pgp regulation during oxidative stress. The currently available data suggest that Pgp has a complex variety of regulatory mechanisms under oxidative stress, involving many transcription factors, the main ones being Nrf2 and Nf-kB. These factors often overlap, and some can be activated under certain conditions, such as the deposition of oxidation products, depending on the severity of oxidative stress. In most cases, the expression of Pgp increases due to increased transcription and translation, but under severe oxidative stress, it can also decrease due to the oxidation of amino acids in its molecule. At the same time, Pgp acts as a protector against oxidative stress, eliminating the causative factors and removing its by-products, as well as participating in signaling pathways.

Improving ADMET Prediction Accuracy for Candidate Drugs: Factors to Consider in QSPR Modeling Approaches

Quantitative Structure-Property Relationship (QSPR) employs mathematical and statistical methods to reveal quantitative correlations between the pharmacokinetics of compounds and their molecular structures, as well as their physical and chemical properties. QSPR models have been widely applied in the prediction of drug absorption, distribution, metabolism, excretion, and toxicity (ADMET). However, the accuracy of QSPR models for predicting drug ADMET properties still needs improvement. Therefore, this paper comprehensively reviews the tools employed in various stages of QSPR predictions for drug ADMET. It summarizes commonly used approaches to building QSPR models, systematically analyzing the advantages and limitations of each modeling method to ensure their judicious application. We provide an overview of recent advancements in the application of QSPR models for predicting drug ADMET properties. Furthermore, this review explores the inherent challenges in QSPR modeling while also proposing a range of considerations aimed at enhancing model prediction accuracy. The objective is to enhance the predictive capabilities of QSPR models in the field of drug development and provide valuable reference and guidance for researchers in this domain.

Evaluation of Novel Benzo-annelated 1,4-dihydropyridines as MDR Modulators in Cancer Cells

BACKGROUND

Multidrug resistance (MDR) is the main problem in anticancer therapy today. Causative transmembrane efflux pumps in cancer cells have been reconsidered as promising anticancer target structures to restore anticancer drug sensitivity by various strategies, including MDR modulators. MDR modulators interfere with the efflux pumps and improve the cellular efficiency of chemotherapeutics. So far, only a few candidates have gone through clinical trials with disappointing results because of low specificity and toxic properties.

AIM

This study aimed to find novel MDR modulators to effectively combat multidrug resistance in cancer cells.

OBJECTIVE

We synthesized various novel benzo-annelated 1,4-dihydropyridines to evaluate them as MDR modulators towards ABCB1 in cancer cells.

METHODS

Synthesized compounds were purified by column chromatography. The MDR modulation of ABCB1 was determined in cellular efflux assays using the flow cytometry technique and cellular fluorescent measurements by the use of each fluorescent substrate.

RESULTS

Compounds were yielded in a two-step reaction with structurally varied components. Further, substituent- dependent effects on the determined MDR inhibiting properties towards ABCB1 were discussed. Cellular studies prove that there is no toxicity and restoration of cancer cell sensitivity towards the used anticancer drug.

CONCLUSION

Novel MDR modulators could be identified with favorable methoxy and ester group functions. Their use in both ABCB1 non-expressing and overexpressing cells proves a selective toxicity-increasing effect of the applied anticancer agent in the ABCB1 overexpressing cells, whereas the toxicity effect of the anticancer drug was almost unchanged in the non-expressing cells. These results qualify our novel compounds as perspective anticancer drugs compared to MDR modulators with nonselective toxicity properties.

Vitexin along with verapamil downregulates efflux pump P-glycoprotein in macrophages and potentiate M1 to M2 switching via TLR4-NF-κB-TNFR2 pathway in lipopolysaccharide treated mice

The lipopolysaccharide, a microbial toxin, is one of the major causative agents of sepsis. P-gp expression and its functions are altered during inflammation. LPS has been known to impair the functions of P-gp, an efflux transporter. But the effect of LPS on P-gp expression in murine peritoneal macrophages is poorly understood. Molecular docking studies reveal that vitexin is a potent substrate and verapamil a potent inhibitor of P-gp. In the present experimental study, the curative potential of vitexin as a fruit component and verapamil treated as a control inhibitor of P-gp was examined in a murine LPS sepsis model. The effects of vitexin and verapamil on P-gp expression in macrophages correlating with changes in macrophage polarization and associated functional responses during LPS induced sepsis were studied. Peritoneal macrophages of LPS (10 mg/kg body weight) challenged mice exhibited elevated levels of H2O2, superoxide, and NO in parallel with lower antioxidant activity. LPS treatment increased P-gp expression through increased TLR4/expression. However, LPS challenged mice treated with vitexin (5 mg/kg body weight) + verapamil (5 mg/kg body weight) showed higher anti-oxidant enzyme activity (SOD, CAT and GRx) resulting in reduced oxidative stress. This combination treatment also elevated TNFR2, concomitant with down-regulation of TLR4, NF-κB and P-gp expression in murine peritoneal macrophages, resulting in a switch from M1 to M2 polarisation of macrophages and reduced inflammatory responses. In conclusion, combined vitexin and verapamil treatment could be used as a promising therapy to regulate P-gp expression and protection against LPS mediated sepsis and inflammatory damages.

Epigenetic modifications: Key players in cancer heterogeneity and drug resistance

Cancer heterogeneity and drug resistance remain pivotal obstacles in effective cancer treatment and management. One major contributor to these challenges is epigenetic modifications - gene regulation that does not involve changes to the DNA sequence itself but significantly impacts gene expression. As we elucidate these phenomena, we underscore the pivotal role of epigenetic modifications in regulating gene expression, contributing to cellular diversity, and driving adaptive changes that can instigate therapeutic resistance. This review dissects essential epigenetic modifications - DNA methylation, histone modifications, and chromatin remodeling - illustrating their significant yet complex contributions to cancer biology. While these changes offer potential avenues for therapeutic intervention due to their reversible nature, the interplay of epigenetic and genetic changes in cancer cells presents unique challenges that must be addressed to harness their full potential. By critically analyzing the current research landscape, we identify knowledge gaps and propose future research directions, exploring the potential of epigenetic therapies and discussing the obstacles in translating these concepts into effective treatments. This comprehensive review aims to stimulate further research and aid in developing innovative, patient-centered cancer therapies. Understanding the role of epigenetic modifications in cancer heterogeneity and drug resistance is critical for scientific advancement and paves the way towards improving patient outcomes in the fight against this formidable disease.

Testosterone replacement therapy: clinical considerations

INTRODUCTION

As an increasingly popular therapeutic option, testosterone replacement therapy (TRT) has gained significant notoriety for its health benefits in indicated populations, such as those suffering from hypogonadism.

AREAS COVERED

Benefits such as improved libido, muscle mass, cognition, and quality of life have led to widened public interest in testosterone as a health supplement. No therapy exists without side effects; testosterone replacement therapy has been associated with side effects such as an increased risk of polycythemia, benign prostate hypertrophy (BPH), prostate cancer, gynecomastia, testicular atrophy, and infertility. Testosterone replacement therapy is often accompanied by several prophylactic co-therapies aimed at reducing the prevalence of these side effects. Literature searches for sections on the clinical benefits and risks associated with TRT were performed to include clinical trials, meta-analyses, and systematic reviews from the last 10 years.

EXPERT OPINION

Data from clinical studies over the last decade suggest that the benefits of this therapy outweigh the risks and result in overall increased quality of life and remission of symptoms related to hypogonadism. With this in mind, the authors of this review suggest that carefully designed clinical trials are warranted for the investigation of TRT in symptomatic age-related hypogonadism.

An In Silico Study of Transforming Growth Factor-β Inhibitors: A Potential Target for Diabetic Nephropathy Treatment with Active Compounds from the Active Fraction of Physalis angulata

Transforming growth factor beta (TGF-β) initiates epithelial-mesenchymal transition (EMT) in tubular and glomerular epithelial cells, resulting in excessive production and deposition of extracellular matrix through its interaction with TGF-β receptors, which play a crucial role in TGF-β signaling involving two receptor types, namely TGF-β type I (TβRI) and type II (TβRII). EMT contributes to the pathogenesis of interstitial renal fibrosis, a marker of end-stage kidney disease. This study aimed to identify the bioactive compounds in the active fraction of P. angulata and evaluate their ability to inhibit the TGF-β activity and their potential as drug candidates. The active components in the active fraction of P. angulata were analyzed using gas chromatography-mass spectrometry (GC-MS). The bioactive compound structures were obtained from the PubChem database, while the protein targets, TβRI and TβRII, were retrieved from the Protein Data Bank (PDB). The molecular docking analyses were performed using PyRx 0.8 and Discovery Studio. SwissADME was used to evaluate ligand properties and druglikeness. Three dominant active compounds were identified, namely palmitic acid, campesterol, and stigmasterol. In silico studies demonstrated strong energy bonds existed between TβRI and palmitic acid, campesterol, stigmasterol, and SB431542 with binding energy values of -5.7, -10, -9.4, and -10.9 kcal/mol, respectively. Similarly, they strongly bound to TβRII with binding energy values of -5.2, -7.1, -7.5, and -6.1 kcal/mol, respectively. All compounds meet Lipinski's criteria for druglikeness. Among the identified active compounds, campesterol exhibited the highest affinity for TβRI, while stigmasterol exhibited a strong affinity for TβRII. These findings suggested that the three compounds have potential as drug candidates.

Antileishmanial Effect of 1,5- and 1,8-Substituted Fused Naphthyridines

In the absence of a vaccine, there is a need to find new drugs for the treatment of neglected tropical diseases, such as leishmaniasis, that can overcome the many drawbacks of those currently used. These disadvantages include cost, the need to maintain a cold chain, the route of administration, the associated adverse effects and the generation of resistance. In this work we have evaluated the antileishmanial effect of 1,5- and 1,8-substituted fused naphthyridines through in vitro and ex vivo assays, using genetically modified axenic and intramacrophagic Leishmania infantum amastigotes. The toxicity of these compounds has been tested in the mammalian host cell using murine splenic macrophages, as well as in murine intestinal organoids (miniguts) in order to assess their potential for oral administration. The 1,8- derivatives showed greater leishmanicidal activity and the presence of a nitrogen atom in the fused ring to the naphthyridine was important to increase the activity of both types of molecules. The aromatization of the pyridine ring also had marked differences in the activity of the compounds.

Differential Effects of Paraquat, Rotenone, and MPTP on Cellular Bioenergetics of Undifferentiated and Differentiated Human Neuroblastoma Cells

Paraquat (PQ), rotenone (RO), and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) are neurotoxicants that can damage human health. Exposure to these neurotoxicants has been linked to neurodegeneration, particularly Parkinson's disease. However, their mechanisms of action have not been fully elucidated, nor has the relative vulnerability of neuronal subtypes to their exposures. To address this, the current study investigated the cytotoxic effects of PQ, RO, and MPTP and their relative effects on cellular bioenergetics and oxidative stress on undifferentiated human neuroblastoma (SH-SY5Y) cells and those differentiated to dopaminergic (DA) or cholinergic (CH) phenotypes. The tested neurotoxicants were all cytotoxic to the three cell phenotypes that correlated with both concentration and exposure duration. At half-maximal effective concentrations (EC50s), there were significant reductions in cellular ATP levels and reduced activity of the mitochondrial complexes I and III, with a parallel increase in lactate production. PQ at 10 µM significantly decreased ATP production and mitochondrial complex III activity only in DA cells. RO was the most potent inhibitor of mitochondrial complex 1 and did not inhibit mitochondrial complex III even at concentrations that induced a 50% loss of cell viability. MPTP was the most potent toxicant in undifferentiated cells. All neurotoxicants significantly increased reactive oxygen species, lipid peroxidation, and nuclear expression of Nrf2, with a corresponding inhibition of the antioxidant enzymes catalase and superoxide dismutase. At a 10 µM exposure to PQ or RO, oxidative stress biomarkers were significant in DA cells. Collectively, this study underscores the importance of mitochondrial dysfunction and oxidative stress in PQ, RO, and MPTP-induced cytotoxicity and that neuronal phenotypes display differential vulnerability to these neurotoxicants.

The Bioavailability of Drugs-The Current State of Knowledge

Drug bioavailability is a crucial aspect of pharmacology, affecting the effectiveness of drug therapy. Understanding how drugs are absorbed, distributed, metabolized, and eliminated in patients' bodies is essential to ensure proper and safe treatment. This publication aims to highlight the relevance of drug bioavailability research and its importance in therapy. In addition to biochemical activity, bioavailability also plays a critical role in achieving the desired therapeutic effects. This may seem obvious, but it is worth noting that a drug can only produce the expected effect if the proper level of concentration can be achieved at the desired point in a patient's body. Given the differences between patients, drug dosages, and administration forms, understanding and controlling bioavailability has become a priority in pharmacology. This publication discusses the basic concepts of bioavailability and the factors affecting it. We also looked at various methods of assessing bioavailability, both in the laboratory and in the clinic. Notably, the introduction of new technologies and tools in this field is vital to achieve advances in drug bioavailability research. This publication also discusses cases of drugs with poorly described bioavailability, providing a deeper understanding of the complex challenges they pose to medical researchers and practitioners. Simultaneously, the article focuses on the perspectives and trends that may shape the future of research regarding bioavailability, which is crucial to the development of modern pharmacology and drug therapy. In this context, the publication offers an essential, meaningful contribution toward understanding and highlighting bioavailability's role in reliable patient treatment. The text also identifies areas that require further research and exploration.