Identification of novel dietary phytochemicals inhibiting the efflux transporter breast cancer resistance protein (BCRP/ABCG2)

Citrus flavonoids for overcoming breast cancer resistance to methotrexate: identification of potential targets of nobiletin and sinensetin

Breast cancer is a potentially fatal illness that affects millions of women worldwide. Methotrexate (MTX) may be beneficial for treating breast cancer; however, high doses and prolonged use can cause drug resistance. Although certain citrus flavonoids-nobiletin, sinensetin, tangeretin, hesperidin, hesperetin, and naringenin-may overcome resistance to chemotherapy, no study has investigated MTX resistance. This study investigated the potential of natural chemicals, specifically nobiletin and sinensetin, to overcome MTX resistance in breast cancer cells using MTX-resistant MCF-7 (MCF-7/MTX) and MCF-7 cells. Protein targets of citrus flavonoids were identified from multiple databases and were collected using Venny 2.1. Microarray data of MCF-7 and MCF-7/MTX cells were acquired from the Gene Expression Omnibus. Subsequently, we constructed a protein-protein interaction network and selected the hub proteins. Gene ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis, drug- and disease-gene enrichment analyses, genetic alteration examination, receiver operating characteristic curve analysis, mRNA levels analysis, prognostic value analysis, and molecular docking analysis were performed along with in vitro experiments. Cytotoxicity of citrus flavonoids (individually and combined) was assessed in MCF-7/MTX cells. Nobiletin and sinensetin significantly enhanced the cytotoxicity of MTX in MCF-7/MTX cells. BCL2L1, CDK1, EGFR, PTGS2, PLK1, MMP2, ACHE, ABCG2, and KIT genes were enriched in cholinesterase activity, cell cycle regulation, and the PI3K/Akt signaling pathway. Nobiletin and sinensetin impeded PLK1, CDK1, and ACHE activities based on molecular docking. Nobiletin and sinensetin in combination with MTX may overcome breast cancer cell resistance to MTX.

Small Phenolic Metabolites at the Nexus of Nutrient Transport and Energy Metabolism

Over time, human metabolism evolved to accommodate the challenges and benefits of plant foods that contain high amounts of carbohydrates and polyphenols. The latter are typically metabolized into small phenolic metabolites, including phenolic acids and their endogenous and microbial derivatives, that influence interconnected metabolic pathways involved in nutrient transport, energy metabolism, and neurotransmitter balance. Unlike other natural products, their biological effects arise from weak interactions with multiple molecular pathways rather than a single high-affinity receptor, making them versatile regulators of metabolic health. These compounds also modulate glucose transporters and carbohydrate metabolism, playing a crucial role in postprandial glucose and insulin responses. This review addresses the critical role of phenolic metabolites in metabolic health, with a focus on glucose homeostasis, insulin sensitivity, and carbohydrate metabolism. Incorporating polyphenols and phenolic acids into dietary strategies offers significant potential for improving insulin sensitivity, reducing metabolic disorder risks, and promoting whole-body glucose homeostasis. Furthermore, understanding how phenolic metabolites interact with metabolic pathways is essential for developing future effective nutritional strategies to support metabolic health.

Much More than Nutrients: The Protective Effects of Nutraceuticals on the Blood-Brain Barrier in Diseases

The dysfunction of the blood-brain barrier (BBB) is well described in several diseases, and is considered a pathological factor in many neurological disorders. This review summarizes the most important groups of natural compounds, including alkaloids, flavonoids, anthocyanidines, carotenoids, lipids, and vitamins that were investigated for their potential protective effects on brain endothelium. The brain penetration of these compounds and their interaction with BBB efflux transporters and solute carriers are discussed. The cerebrovascular endothelium is considered a therapeutic target for natural compounds in diseases. In preclinical studies modeling systemic and central nervous system diseases, nutraceuticals exerted beneficial effects on the BBB. In vivo, they decreased BBB permeability, brain edema, astrocyte swelling, and morphological changes in the vessel structure and basal lamina. At the level of brain endothelial cells, nutraceuticals increased cell survival and decreased apoptosis. From the general endothelial functions, decreased angiogenesis and increased levels of vasodilating agents were demonstrated. From the BBB functions, elevated barrier integrity by tightened intercellular junctions, and increased expression and activity of BBB transporters, such as efflux pumps, solute carriers, and metabolic enzymes, were shown. Nutraceuticals enhanced the antioxidative defense and exerted anti-inflammatory effects at the BBB. The most important signaling changes mediating the increased cell survival and BBB stability were the activation of the WNT, PI3K-AKT, and NRF2 pathways, and inhibition of the MAPK, JNK, ERK, and NF-κB pathways. Nutraceuticals represent a valuable source of new potentially therapeutic molecules to treat brain diseases by protecting the BBB.

Celastrol boosts fluconazole efficacy against vaginal candidiasis: in vitro and in vivo evidence

Candida albicans is a commensal fungus that naturally inhabits the vagina. However, overgrowth of C. albicans can result in vulvovaginal candidiasis (VVC), one of the most prevalent fungal infections affecting women. The rapid emergence of azole resistance in C. albicans, in addition to the limited available antifungal agents, complicates the treatment and emphasizes the urgent need for novel therapeutic options. Efflux-mediated azole resistance is a common resistance mechanism in fluconazole (FLZ)-resistant C. albicans. Combination therapy using natural compounds is a potential approach that can restore fluconazole's antifungal activity in azole-resistant isolates via efflux pump inhibition. This study aimed to evaluate the ability of celastrol, a natural triterpene, to retrieve FLZ antifungal activity against azole-resistant C. albicans in vitro and in vivo. Celastrol did not exhibit antifungal activity against the tested clinical isolates; however, the sub-MIC of celastrol inhibited rhodamine 6G (R6G) efflux and increased R6G accumulation inside celastrol-treated C. albicans cells. Synergy was spotted between celastrol and FLZ via a checkerboard assay. Quantification of m-RNA levels of efflux-mediated azole resistance genes within azole-resistant C. albicans demonstrated CDR1 overexpression. Upon celastrol treatment, a significant decline in ABC transporters transcript levels were detected. Moreover, molecular docking demonstrated that celastrol is a potential ABC efflux transporters blocker that successfully fits into target binding pockets. A negligible hemolytic effect of celastrol against human erythrocytes was observed. In the in vivo model of VVC, the combination of FLZ and celastrol in vaginal gel revealed a drastic reduction in the fungal burden with apparently normal vaginal tissue. Celastrol promising in vitro and in vivo findings strengthen its future use for the treatment of azole-resistant C. albicans.

Potential Interaction of Pinocembrin with Drug Transporters and Hepatic Drug-Metabolizing Enzymes

Background/Objectives: Pinocembrin is a promising drug candidate for treating ischemic stroke. The interaction of pinocembrin with drug transporters and drug-metabolizing enzymes is not fully revealed. The present study aims to evaluate the interaction potential of pinocembrin with cytochrome P450 (CYP450: CYP2B6, CYP2C9, and CYP2C19) and drug transporters including organic anion transporters (OAT1 and OAT3), organic cation transporters (OCT1 and OCT2), multidrug and toxin extrusion (MATE1 and MATE2, P-glycoprotein (P-gp), and breast cancer resistance protein (BCRP). Methods: The interactions of pinocembrin on drug transporters were determined in the Madin-Darby canine kidney (MDCK) cells overexpressing human (h)OAT1 or hOAT3 and in the Chinese hamster ovary (CHO-K1) cells overexpressing hOCT1, hOCT2, hMATE1, or hMATE2. The interactions of pinocembrin with BCRP and P-glycoprotein were determined in Caco-2 cells. The CYP450 enzyme inhibitory activity was assessed by a cell-free CYP450 screening assay. Results: Pinocembrin effectively inhibited the function of OAT1 and OAT3 with a half-inhibitory concentration (IC50) and inhibitory constant (Ki) of ∼2 μM. In addition, it attenuated the toxicity of tenofovir, a substrate of hOAT1, in cells overexpressing hOAT1. Based on the kinetic study and molecular docking, pinocembrin inhibited OAT1 and OAT3 via a competitive inhibition. In contrast to hOAT1 and hOAT3, pinocembrin did not significantly inhibit the function of OCT1, OCT2, MATE1, MATE2, BCRP, and P-glycoprotein. In addition, pinocembrin potently inhibited the activity of CYP2C19, whereas it exhibited low inhibitory potency on CYP2B6 and CYP2C9. Conclusions: The present study reveals the potential drug interaction of pinocembrin on OAT1, OAT3, and CYP2C19. Co-administration with pinocembrin might affect OAT1-, OAT3-, and CYP2C19-mediated drug pharmacokinetic profiles.

Medicinal plants as a potential resource for the discovery of novel structures towards cancer drug resistance treatment

Despite extensive research in chemotherapy, global cancer concerns persist, exacerbated by the challenge of drug resistance, which imposes economic and medical burdens. Natural compounds, particularly secondary metabolites from medicinal plants, present promising avenues for overcoming cancer drug resistance due to their diverse structures and essential pharmacological effects. This review provides a comprehensive exploration of cancer cell resistance mechanisms and target actions for reversing resistance and highlights the in vitro and in vivo efficacy of noteworthy alkaloids, flavonoids, and other compounds, emphasizing their potential as therapeutic agents. The molecular properties supporting ligand interactions are thoroughly examined, providing a robust theoretical foundation. The review concludes by discussing methods including quantitative structure-activity relationships and molecular docking, offering insights into screening potential candidates. Current trends in clinical treatment, contributing to a holistic understanding of the multifaceted approaches to address cancer drug resistance are also outlined.

Effect of Oregon grape root extracts on P-glycoprotein mediated transport in in vitro cell lines

Purpose: This study aims to investigate the potential of Oregon grape root extracts to modulate the activity of P-glycoprotein. Methods: We performed 3H-CsA or 3H-digoxin transport experiments in the absence or presence of two sources of Oregon grape root extracts (E1 and E2), berberine or berbamine in Caco-2 and MDCKII-MDR1 cells. In addition, real time quantitative polymerase chain reaction (RT-PCR) was performed in Caco-2 and LS-180 cells to investigate the mechanism of modulating P-glycoprotein. Results: Our results showed that in Caco-2 cells, Oregon grape root extracts (E1 and E2) (0.1-1 mg/mL) inhibited the efflux of CsA and digoxin in a dose-dependent manner. However, 0.05 mg/mL E1 significantly increased the absorption of digoxin. Ten µM berberine and 30 µM berbamine significantly reduced the efflux of CsA, while no measurable effect of berberine was observed with digoxin. In the MDCKII-MDR1 cells, 10 µM berberine and 30 µM berbamine inhibited the efflux of CsA and digoxin. Lastly, in real time RT-PCR study, Oregon grape root extract (0.1 mg/mL) up-regulated mRNA levels of human MDR1 in Caco-2 and LS-180 cells at 24 h. Conclusion: Our study showed that Oregon grape root extracts modulated P-glycoprotein, thereby may affect the bioavailability of drugs that are substrates of P-glycoprotein.

Research Progress of Tamarixetin and its Glycosides

Tamarixetin and its glycosides are widely distributed in natural plants, and they are also natural flavonoid derivatives of quercetin. Its main pharmacological effects include antioxidant, antiinflammatory, antiviral, anticancer, cardiovascular effects, etc. The pharmacokinetics showed that the distribution of direct absorption differed from that of biosynthesis. At the same time, research shows that tamarixetin is safe to use because it has little self-toxicity. In this paper, 181 articles on tamarixetin published from 1976 to 2023 are obtained from PubMed, China Knowledge Base Database, Wanfang Data, and other electronic databases. Tamarixetin is searched based on keywords, and 121 articles remain. Transformation synthesis, pharmacokinetics, pharmacological action, and structureactivity relationship of tamarixetin were reviewed.

Evaluation of the Mechanism of Yishan Formula in Treating Breast Cancer Based on Network Pharmacology and Experimental Verification

BACKGROUND

Yishan formula (YSF) has a significant effect on the treatment of breast cancer, which can improve the quality of life and prolong the survival of patients with breast cancer; however, its mechanism of action is unknown.

OBJECTIVE

In this study, network pharmacology and molecular docking methods have been used to explore the potential pharmacological effects of the YSF, and the predicted targets have been validated by in vitro experiments.

METHODS

Active components and targets of the YSF were obtained from the TCMSP and Swiss target prediction website. Four databases, namely GeneCards, OMIM, TTD, and DisGeNET, were used to search for disease targets. The Cytoscape v3.9.0 software was utilized to draw the network of drug-component-target and selected core targets. DAVID database was used to analyze the biological functions and pathways of key targets. Finally, molecular docking and in vitro experiments have been used to verify the hub genes.

RESULTS

Through data collection from the database, 157 active components and 618 genes implicated in breast cancer were obtained and treated using the YSF. After screening, the main active components (kaempferol, quercetin, isorhamnetin, dinatin, luteolin, and tamarixetin) and key genes (AKT1, TP53, TNF, IL6, EGFR, SRC, VEGFA, STAT3, MAPK3, and JUN) were obtained. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis indicated that the YSF could affect the progression of breast cancer by regulating biological processes, such as signal transduction, cell proliferation and apoptosis, protein phosphorylation, as well as PI3K-Akt, Rap1, MAPK, FOXO, HIF-1, and other related signaling pathways. Molecular docking suggested that IL6 with isorhamnetin, MAPK3 with kaempferol, and EGFR with luteolin have strong binding energy. The experiment further verified that YSF can control the development of breast cancer by inhibiting the expression of the hub genes.

CONCLUSION

This study showed that resistance to breast cancer may be achieved by the synergy of multiple active components, target genes, and signal pathways, which can provide new avenues for breast cancer-targeted therapy.

Caffeic Acid Phenethyl Ester: A Potential Therapeutic Cancer Agent?

BACKGROUND

Propolis and its major phenolic compound, caffeic acid phenethyl ester (CAPE), have garnered considerable scientific interest due to their anti- inflammatory properties and potential therapeutic applications.

OBJECTIVES

This narrative review explores the potential utility of CAPE in cancer treatment.

METHODS

We comprehensively reviewed relevant studies from scientific databases (PubMed and Web of Science) from 2000 to 2022. Our search focused on keywords such as cancer, natural drugs, caffeic acid phenethyl ester, CAPE, cancer cell lines, antitumor effects, and propolis.

RESULTS

CAPE exhibits diverse biological benefits, including antimicrobial, antioxidant, antiviral, anti-inflammatory, cytotoxic, and potentially anti-carcinogenic properties. Numerous studies have demonstrated its wide-ranging antitumor effects on various cancer cell lines, including growth inhibition, apoptosis induction, tumor invasiveness prevention, malignancy suppression, and anti-angiogenic activity.

CONCLUSION

Following comprehensive preclinical toxicity assessments, further evaluation of CAPE's efficacy and safety through clinical trials is highly recommended to elucidate its potential health benefits in diverse forms of human cancer.

Polyphenols and Their Impact on the Prevention of Neurodegenerative Diseases and Development

It is well known that neurodegenerative diseases' development and progression are accelerated due to oxidative stress and inflammation, which result in impairment of mitochondrial function, cellular damage, and dysfunction of DNA repair systems. The increased consumption of antioxidants can postpone the development of these disorders and improve the quality of patients' lives who have already been diagnosed with neurodegenerative diseases. Prolonging life span in developed countries contributes to an increase in the incidence ratio of chronic age-related neurodegenerative disorders, such as PD (Parkinson's disease), AD (Alzheimer's disease), or numerous forms of age-related dementias. Dietary supplementation with neuroprotective plant-derived polyphenols might be considered an important element of healthy aging. Some polyphenols improve cognition, mood, visual functions, language, and verbal memory functions. Polyphenols bioavailability differs greatly from one compound to another and is determined by solubility, degree of polymerization, conjugation, or glycosylation resulting from chemical structure. It is still unclear which polyphenols are beneficial because their potential depends on efficient transport across the BBB (blood-brain barrier), bioavailability, and stability in the CNS (central nervous system). Polyphenols improve brain functions by having a direct impact on cells and processes in the CNS. For a direct effect, polyphenolic compounds must be able to overcome the BBB and accumulate in brain tissue. In this review, the latest achievements in studies (animal models and clinical trials) on the effect of polyphenols on brain activity and function are described. The beneficial impact of plant polyphenols on the brain may be summarized by their role in increasing brain plasticity and related cognition improvement. As reversible MAO (monoamine oxidase) inhibitors, polyphenols are mood modulators and improve neuronal self-being through an increase in dopamine, serotonin, and noradrenaline amounts in the brain tissue. After analyzing the prohealth effects of various eating patterns, it was postulated that their beneficial effects result from synergistic interactions between individual dietary components. Polyphenols act on the brain endothelial cells and improve the BBB's integrity and reduce inflammation, thus protecting the brain from additional injury during stroke or autoimmune diseases. Polyphenolic compounds are capable of lowering blood pressure and improving cerebral blood flow. Many studies have revealed that a nutritional model based on increased consumption of antioxidants has the potential to ameliorate the cognitive impairment associated with neurodegenerative disorders. Randomized clinical trials have also shown that the improvement of cognitive functions resulting from the consumption of foods rich in flavonoids is independent of age and health conditions. For therapeutic use, sufficient quantities of polyphenols must cross the BBB and reach the brain tissue in active form. An important issue in the direct action of polyphenols on the CNS is not only their penetration through the BBB, but also their brain metabolism and localization. The bioavailability of polyphenols is low. The most usual oral administration also conflicts with bioavailability. The main factors that limit this process and have an effect on therapeutic efficacy are: selective permeability across BBB, gastrointestinal transformations, poor absorption, rapid hepatic and colonic metabolism, and systemic elimination. Thus, phenolic compounds have inadequate bioavailability for human applications to have any beneficial effects. In recent years, new strategies have been attempted in order to exert cognitive benefits and neuroprotective effects. Converting polyphenols into nanostructures is one of the theories proposed to enhance their bioavailability. The following nanoscale delivery systems can be used to encapsulate polyphenols: nanocapsules, nanospheres, micelles, cyclodextrins, solid lipid nanoparticles, and liposomes. It results in great expectations for the wide-scale and effective use of polyphenols in the prevention of neurodegenerative diseases. Thus far, only natural polyphenols have been studied as neuroprotectors. Perhaps some modification of the chemical structure of a given polyphenol may increase its neuroprotective activity and transportation through the BBB. However, numerous questions should be answered before developing neuroprotective medications based on plant polyphenols.

Can the phenolic compounds of Manuka honey chemosensitize colon cancer stem cells? A deep insight into the effect on chemoresistance and self-renewal

Manuka honey, which is rich in pinocembrin, quercetin, naringenin, salicylic, p-coumaric, ferulic, syringic and 3,4-dihydroxybenzoic acids, has been shown to have pleiotropic effects against colon cancer cells. In this study, potential chemosensitizing effects of Manuka honey against 5-Fluorouracil were investigated in colonspheres enriched with cancer stem cells (CSCs), which are responsible for chemoresistance. Results showed that 5-Fluorouracil increased when it was combined with Manuka honey by downregulating the gene expression of both ATP-binding cassette sub-family G member 2, an efflux pump and thymidylate synthase, the main target of 5-Fluorouracil which regulates the ex novo DNA synthesis. Manuka honey was associated with decreased self-renewal ability by CSCs, regulating expression of several genes in Wnt/β-catenin, Hedgehog and Notch pathways. This preliminary study opens new areas of research into the effects of natural compounds in combination with pharmaceuticals and, potentially, increase efficacy or reduce adverse effects.

Study on herb-herb interaction between active components of Plantago asiatica L. seed and Coptis chinensis Franch. rhizoma based on transporters using UHPLC-MS/MS

The combined efficacy in lowering serum lipid levels and increasing kidney protection of Plantago asiatica L. seed (Plantago) and Coptis chinensis Franch. rhizoma (Coptis) is far better than the effects of either herb alone. This finding suggests that there must be some degree of herb-herb interactions (HHI) affect potency. Here, we chose geniposidic acid (GPA), acteoside (ACT), and plantagoamidinic acid A (PLA) as active components in Plantago, and berberine (BBR) as the active component in Coptis, and, using transporter gene-transfected Madin-Darby canine kidney (MDCK) cells in combination with specific substrates and inhibitors, investigated Plantago- Coptis HHIs. We also established a UPLC-MS/MS analytical method to determine substrate content. Results showed that PLA in Plantago was a substrate of rOCT1/2 and rMATE1, and had inhibitory effects on rOCT2 and rMATE1. We also found that ACT is a substrate of rMATE1, but GPA was not a substrate of any transporter that we investigated. When BBR was used as the substrate, the inhibition rate of 10 μM PLA was 53.6% on rOCT2 and 31.5% on rMATE1. The inhibition rates of 30 μM ACT and 30 μM GPA on rMATE1 were 47.0% and 31.0%, respectively. Thus, our findings suggest that GPA, ACT, PLA, and BBR have competitive interactions that are driven by the rOCT2 and rMATE1 transporters. These interactions affect the transport and excretion of compounds and result in efficacy changes after co-administration.

Natural Products as a Tool to Modulate the Activity and Expression of Multidrug Resistance Proteins of Intestinal Barrier

The role of intestinal barrier homeostasis in an individual’s general well-being has been widely addressed by the scientific community. Colorectal cancer is among the illnesses that most affect this biological barrier. While chemotherapy is the first choice to treat this type of cancer, multidrug resistance (MDR) is the major setback against the commonly used drugs, with the ATP-binding cassette transporters (ABC transporters) being the major players. The role of P-glycoprotein (P-gp), multidrug resistance protein 1 (MRP1), or breast cancer resistance protein (ABCG2) in the efflux of chemotherapeutic drugs is well described in cancer cells, highlighting these proteins as interesting druggable targets to reverse MDR, decrease drug dosage, and consequently undesired toxicity. Natural products, especially phytochemicals, have a wide diversity of chemical structures, and some particular classes, such as phenolic acids, flavonoids, or pentacyclic triterpenoids, have been reported as inhibitors of P-gp, MRP1, and ABCG2, being able to sensitize cancer cells to chemotherapy drugs. Nevertheless, ABC transporters play a vital role in the cell’s defense against xenobiotics, and some phytochemicals have also been shown to induce the transporters’ activity. A balance must be obtained between xenobiotic efflux in non-tumor cells and bioaccumulation of chemotherapy drugs in cancer cells, in which ABC transporters are essential and natural products play a pivotal role that must be further analyzed. This review summarizes the knowledge concerning the nomenclature and function of ABC-transporters, emphasizing their role in the intestinal barrier cells. In addition, it also focuses on the role of natural products commonly found in food products, e.g., phytochemicals, as modulators of ABC-transporter activity and expression, which are promising nutraceutical molecules to formulate new drug combinations to overcome multidrug resistance.

The Spectrum of Pharmacological Actions of Syringetin and Its Natural Derivatives-A Summary Review

Mono- and poly-O-methylated flavonols and their glycoside derivatives belong to the group of natural plant polyphenols with a wide spectrum of pharmacological activities. These compounds are known for their antioxidant, antimutagenic, hepatoprotective, antidiabetic, and antilipogenic properties. Additionally, they inhibit carcinogenesis and cancer development. Having in mind the multidirectional biological activity of methylated flavonols, we would like to support further study on their health-promoting activities; in this review we summarized the most recent reports on syringetin and some of its structural analogues: laricitrin, ayanin, and isorhamnetin. Natural sources and biological potential of these substances were described based on the latest research papers.

Systematic understanding of anti-tumor mechanisms of Tamarixetin through network and experimental analyses

Tamarixetin, a flavonoid derived from Quercetin, was shown to possess anti-cancer properties in various types of cancer. However, the mechanism of action of this compound is not well understood. Observations from reverse docking and network pharmacology analysis, were validated by cell based studies to analyse the chemotherapeutic potential and elucidate the molecular mechanism of action of Tamarixetin in breast cancer. In silico analysis using reverse docking and PPI analysis clearly indicated that out of 35 proteins targeted by Tamarixetin, the top 3 hub genes, namely, AKT1, ESR1 and HSP90AA1, were upregulated in breast tumor tissues and more importantly showed strong negative correlation to breast cancer patient survival. Furthermore, the KEGG pathway analysis showed enrichment of target proteins of Tamarixetin in 33 pathways which are mainly involved in neoplastic signalling. In vitro cell-based studies demonstrated that Tamarixetin could inhibit cell proliferation, induce ROS and reduce mitochondrial membrane potential, leading to cell death. Tamarixetin induced cell cycle arrest at G2/M phase and inhibited the migration as well as the invasion of breast cancer cells. Taken together, the combination of in silico and in vitro approaches used in the present study clearly provides evidence for the chemotherapeutic potential of Tamarixetin in breast cancer.

Combination of multifunctional ursolic acid with kinase inhibitors for anti-cancer drug carrier vesicles

A sterically stabilized unilamellar nanocarrier vesicle (SSV) system containing dipalmitoylphosphatidylcholine, cholesterol, ursolic acid and PEGylated phospholipid has been developed by exploiting the structural advantages of ursolic acid: by spontaneously attaching to the lipid head groups, it induces curvature at the outer side of the bilayers, allowing the preparation of size-limited vesicles without extrusion. Ursolic acid (UA) also interacts with the PEG chains, supporting steric stabilization even when the amount of PEGylated phospholipid is reduced. Using fluorescence immunohistochemistry, vesicles containing ursolic acid (UA-SSVs) were found to accumulate in the tumor in 3 h on xenografted mouse, suggesting the potential use of these vesicles for passive tumor targeting. Further on, mono- and combination therapy with UA and six different kinase inhibitors (crizotinib, erlotinib, foretinib, gefitinib, refametinib, trametinib) was tested on seven cancer cell-lines. In most combinations synergism was observed, in the case of trametinib even at very low concentration (0.001 μM), which targets the MAPK pathway most often activated in human cancers. The coupled intercalation of UA and trametinib (2:1 molar ratio) into vesicles causes further structural advantageous molecular interactions, promoting the formation of small vesicles. The high drug:lipid molar ratio (~0.5) in the novel type of co-delivery vesicles enables their direct medical application, possibly also overcoming the multidrug resistance effect.

Phytodentistry in Africa: prospects for head and neck cancers

Background

Orthodox dentistry has undergone significant changes in recent times with the introduction of various omics and molecular targeted therapies both at the experimental/trial and clinical implementation level. Although, significant milestones have been achieved in the molecular dentistry field in the past decade, there remains a dearth of application of phytopharmacological innovation in personalized and targeted therapies for dental diseases.

Main body

From time immemorial, plant products have long been an integral aspect of dental practice ranging from chewing sticks/herbal kinds of toothpaste to dental/impression materials. The current era of precision medicine seeks to apply a multipronged molecular and bio-computational approaches to solve fundamental medical problems that have hitherto remained difficult. Remarkable changes in the molecular/omics era, have transformed empirical therapies into personalized/individualized ones. Furthermore, the combinatorial application and the widespread introduction of high-throughput molecular tools such as pharmacogenomics, phytopharmacology, metabolomics, mathematical modelling, and genetic engineering inter alia, has tremendously improved the diagnostic and therapeutic landscape of medicine. Additionally, the variable molecular epidemiology of diseases among different population and emerging molecular evidence warrants the use of customized novel theranostic techniques. Unfortunately, the footprint of such emerging application is sparse in dental diseases such as maxillofacial cancers.

Conclusion

Hence, this review seeks to evaluate the potential application of phytopharmacological approaches to head and neck cancers in a resource-limited environment, such as Africa.

Drug-Exposome Interactions: The Next Frontier in Precision Medicine

Drug-drug interactions are a known concern during medical treatment. However, in addition to therapeutic drugs, humans are exposed to thousands of environment- and food-related chemicals on a daily basis. The exposome (i.e.,the total measure of environmental factors on the human body) is an emerging concept in the field of environmental health. Many chemicals have the potential to interact with drugs and subsequently influence health outcomes. To date, this concept has not been systematicallyinvestigated. Nevertheless, adverse effects have been observed betweenenvironmental, dietary, and microbiome-derived xenobiotics and a number of drugs, including chemotherapeutics. Recent technological advances in mass spectrometry-based metabolomics and the establishment of omic-scale exposure assessment will enable a broader and systemic investigation of these interactions. As a complement to pharmacogenomics and pharmacometabolomics, research ondrug-exposome interactions holds immense potential to elevate precision medicineto an unprecedented level.

Sinensetin: An Insight on Its Pharmacological Activities, Mechanisms of Action and Toxicity

Sinensetin, a plant-derived polymethoxylated flavonoid found in Orthosiphon aristatus var. aristatus and several citrus fruits, has been found to possess strong anticancer activities and a variety of other pharmacological benefits and promising potency in intended activities with minimal toxicity. This review aims to compile an up-to-date reports of published scientific information on sinensetin pharmacological activities, mechanisms of action and toxicity. The present findings about the compound are critically analyzed and its prospect as a lead molecule for drug discovery is highlighted. The databases employed for data collection are mainly through Google Scholar, PubMed, Scopus and Science Direct. In-vitro and in-vivo studies showed that sinensetin possessed strong anticancer activities and a wide range of pharmacological activities such as anti-inflammatory, antioxidant, antimicrobial, anti-obesity, anti-dementia and vasorelaxant activities. The studies provided some insights on its several mechanisms of action in cancer and other disease states. However, more detail mechanistic studies are needed to understand its pharmacological effects. More in vivo studies in various animal models including toxicity, pharmacokinetic, pharmacodynamic and bioavailability studies are required to assess its efficacy and safety before submission to clinical studies. In this review, an insight on sinensetin pharmacological activities and mechanisms of action serves as a useful resource for a more thorough and comprehensive understanding of sinensetin as a potential lead candidate for drug discovery.

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

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

Ursolic acid: A systematic review of its pharmacology, toxicity and rethink on its pharmacokinetics based on PK-PD model

Ursolic acid (UA) is a natural pentacyclic triterpenoid compound existing in various traditional Chinese medicinal herbs, and it possesses diverse pharmacological actions and some undesirable adverse effects, even toxicological activities. Due to UA's low solubility and poor bioavailability, and its interaction with gut microbiota after oral administration, the pharmacokinetics of UA remain elusive, leading to obscurity in the pharmacokinetics-pharmacodynamics (PK-PD) profile and relationship for UA. Based on literatures from PubMed, Google Scholar, ResearchGate, Web of Science and Wiley Online Library, with keywords of "pharmacology", "toxicology", "pharmacokinetics", "PK-PD" and "ursolic acid", herein we systematically review the pharmacology and toxicity of UA, and rethink on its pharmacokinetics on the basis of PK-PD model, and seek to delineate the underlying mechanisms for the characteristics of pharmacology and toxicology of UA, and for the pharmacokinetic features of UA particularly from the organ tropism and the interactions between UA and gut microbiota, and lay a solid foundation for development of UA-derived therapeutic agents in clinical settings.

Effects of Selected Nigerian Medicinal Plants on the Viability, Mobility, and Multidrug-Resistant Mechanisms in Liver, Colon, and Skin Cancer Cell Lines

Medicinal plants indicated for chronic diseases usually have good safety margins as they are intended for lifelong treatments. We hypothesized that they may provide patients with baseline protection to cancers and multidrug resistance-reversing phytochemicals resulting in successful prevention and/or adjuvant treatment of chemotherapy-resistant cancers. We selected 27 popular herbal infusions widely used in Nigeria for diabetes and studied their effects on a panel of liver (HepG2), colon (Caco2), and skin (B16-F10) cancer cells. Cytotoxicity was measured using the SRB staining assay. The 2D antimigratory effect was evaluated using an Oris™ platform. The P-glycoprotein (P-gp) efflux activity was evaluated using Rh-123 as a fluorescent probe. The inhibition of tyrosinase-mediated melanogenesis was evaluated by colorimetric enzymatic assays. Our results show that melanoma cell proliferation was strongly inhibited by Anogeissus leiocarpus (Combretaceae), Bridelia ferruginea (Phyllanthaceae), D. ogea (Leguminosae), and Syzygium guineense (Myrtaceae) extracts (G_{I50 =} 50 µg/ml). Alstonia boonei (Apocynaceae), Gongronema latifolium (Asclepiadaceae), and Strophanthus hispidus (Apocynaceae) were preferentially toxic against Caco2 (GI_{50 =} 50, 5 and 35 µg/ml, respectively). The most active extracts against different drug resistance mechanisms were B. ferruginea (inhibition of P-gp efflux, and impairing tyrosinase activity) and X. americana (inhibition of P-gp efflux). A. leiocarpus, Kaya senegalensis (Meliaceae), S. guineense, and Terminalia avicennioides (Combretaceae) significantly inhibited B16-F10 cell migration. Lupeol, ursolic acid, quercitrin, epicatechin, gallic acid, and ellagic acid were dereplicated by HPLC and HPTLC as their bioactive phytochemicals. In conclusion, the above in-vitro activities of herbal infusions regularly consumed by Nigerian diabetic patients may either act as a baseline chemoprotection or as sensitizing agents.

Soy Isoflavone Genistein Inhibits an Axillary Osmidrosis Risk Factor ABCC11: In Vitro Screening and Fractional Approach for ABCC11-Inhibitory Activities in Plant Extracts and Dietary Flavonoids

Axillary osmidrosis (AO) is a common chronic skin condition characterized by unpleasant body odors emanating from the armpits, and its aetiology is not fully understood. AO can seriously impair the psychosocial well-being of the affected individuals; however, no causal therapy has been established for it other than surgical treatment. Recent studies have revealed that human ATP-binding cassette transporter C11 (ABCC11) is an AO risk factor when it is expressed in the axillary apocrine glands-the sources of the offensive odors. Hence, identifying safe ways to inhibit ABCC11 may offer a breakthrough in treating AO. We herein screened for ABCC11-inhibitory activities in 34 natural products derived from plants cultivated for human consumption using an in vitro assay system to measure the ABCC11-mediated transport of radiolabeled dehydroepiandrosterone sulfate (DHEA-S-an ABCC11 substrate). The water extract of soybean (Glycine max) was found to exhibit the strongest transport inhibition. From this extract, via a fractionation approach, we successfully isolated and identified genistein, a soy isoflavone, as a novel ABCC11 inhibitor with a half-maximal inhibitory concentration value of 61.5 μM. Furthermore, we examined the effects of other dietary flavonoids on the ABCC11-mediated DHEA-S transport to uncover the effects of these phytochemicals on ABCC11 function. While further human studies are needed, our findings here about the natural compounds will help develop a non-surgical therapy for AO.

Cancer stem cells and nanomedicine: new opportunities to combat multidrug resistance?

'Multidrug resistance' (MDR) is a difficult challenge for cancer treatment. The combined role of cytochrome P450 enzymes (CYPs) and active efflux transporters (AETs) in cancer cells appears relevant in inducing MDR. Chemotherapeutic drugs can be substrates of both CYPs and AETs and CYP inducers or inhibitors can produce the same effects on AETs. In addition, a small subpopulation of cancer stem-like cells (CSCs) appears to survive conventional chemotherapy, leading to recurrent disease. Natural products appear efficacious against CSCs; their combinational treatments with standard chemotherapy are promising for cancer eradication, in particular when supported by nanotechnologies.

Wilforine resensitizes multidrug resistant cancer cells via competitive inhibition of P-glycoprotein

BACKGROUND AND PURPOSE

Multidrug resistance (MDR) remains the main obstacle in cancer treatment and overexpression of P-glycoprotein (P-gp) is one of the most common causes of chemoresistance. The development of novel P-gp inhibitors from natural products is a prospective strategy to combat MDR cancers. Among the natural sesquiterpene compounds, sesquiterpene pyridine alkaloids exhibit various biological properties. Therefore, in the present study, we evaluated the modulatory effects of wilforine on P-gp expression and function. The molecular mechanisms and kinetic models of wilforine-mediated P-gp inhibition were further investigated.

METHODS

The human P-gp stable expression cells (ABCB1/Flp-In^TM-293) and human cervical cancer cells (sensitive: HeLaS3; MDR: KBvin) were used. The cell viability was assessed by SRB assay. The inhibitory effect of wilforine on P-gp efflux and the underlying mechanism were evaluated by assays for calcein-AM uptake, rhodamine123 and doxorubicin efflux, ATPase activity, real-time quantitative RT-PCR, apoptosis, and cell cycle analysis. Molecular docking was performed by the docking software CDOCKER with BIOVIA Discovery Studio 4.5 (D.S. 4.5).

RESULTS

We found that wilforine significantly inhibited the efflux activity of P-gp in a concentration-dependent manner. Further kinetic analysis demonstrated that wilforine significantly inhibited P-gp efflux function by competitive inhibition and stimulated the basal P-gp ATPase activity. In addition, wilforine re-sensitized MDR cancer cells to chemotherapeutic drugs. The docking model indicated that wilforine was bound to residues of P-gp such as LEU884, LYS887, THR176 and ASN172.

CONCLUSION

These results suggest a novel future therapeutic strategy for MDR cancer using wilforine as an adjuvant treatment with chemotherapy.

Phenolic compounds from Mediterranean foods as nutraceutical tools for the prevention of cancer: The effect of honey polyphenols on colorectal cancer stem-like cells from spheroids

Chemoresistance and development of relapses are ascribable to a rare cell population of tumour mass: cancer stem cells (CSCs). Targeting CSCs could increase patients' survival rate and it is important to identify molecules that can act on the main pathways of these cells. Natural bioactive compounds, of which Manuka honey (MH) is rich, could be a good opportunity to target them. This work aims to evaluate the effect of MH on CSCs-like from human colorectal carcinoma (HCT-116 cell line) enriched through the in vitro sphere-forming assay. The results showed that MH reduced the volume of the entire culture of spheroids, affecting also their morphological parameters and induced apoptosis and ROS intracellular accumulation in CSCs-like. In addition, MH decreased the mRNA expression of one of ABC transporters (ABCG2) and affected self-renewal ability through the downregulation of the mRNA expression of one of the receptor membranes of Wnt/β-catenin pathway (Frizzled 7).

ADMET evaluation in drug discovery. 20. Prediction of breast cancer resistance protein inhibition through machine learning

Breast cancer resistance protein (BCRP/ABCG2), an ATP-binding cassette (ABC) efflux transporter, plays a critical role in multi-drug resistance (MDR) to anti-cancer drugs and drug–drug interactions. The prediction of BCRP inhibition can facilitate evaluating potential drug resistance and drug–drug interactions in early stage of drug discovery. Here we reported a structurally diverse dataset consisting of 1098 BCRP inhibitors and 1701 non-inhibitors. Analysis of various physicochemical properties illustrates that BCRP inhibitors are more hydrophobic and aromatic than non-inhibitors. We then developed a series of quantitative structure–activity relationship (QSAR) models to discriminate between BCRP inhibitors and non-inhibitors. The optimal feature subset was determined by a wrapper feature selection method named rfSA (simulated annealing algorithm coupled with random forest), and the classification models were established by using seven machine learning approaches based on the optimal feature subset, including a deep learning method, two ensemble learning methods, and four classical machine learning methods. The statistical results demonstrated that three methods, including support vector machine (SVM), deep neural networks (DNN) and extreme gradient boosting (XGBoost), outperformed the others, and the SVM classifier yielded the best predictions (MCC = 0.812 and AUC = 0.958 for the test set). Then, a perturbation-based model-agnostic method was used to interpret our models and analyze the representative features for different models. The application domain analysis demonstrated the prediction reliability of our models. Moreover, the important structural fragments related to BCRP inhibition were identified by the information gain (IG) method along with the frequency analysis. In conclusion, we believe that the classification models developed in this study can be regarded as simple and accurate tools to distinguish BCRP inhibitors from non-inhibitors in drug design and discovery pipelines.

Citrus Flavones: An Update on Sources, Biological Functions, and Health Promoting Properties

Citrus spp. are among the most widespread plants cultivated worldwide and every year millions of tons of fruit, juices, or processed compounds are produced and consumed, representing one of the main sources of nutrients in human diet. Among these, the flavonoids play a key role in providing a wide range of health beneficial effects. Apigenin, diosmetin, luteolin, acacetin, chrysoeriol, and their respective glycosides, that occur in concentrations up to 60 mg/L, are the most common flavones found in Citrus fruits and juices. The unique characteristics of their basic skeleton and the nature and position of the substituents have attracted and stimulated vigorous investigations as a consequence of an enormous biological potential, that manifests itself as (among other properties) antioxidant, anti-inflammatory, antiviral, antimicrobial, and anticancer activities. This review analyzes the biochemical, pharmacological, and biological properties of Citrus flavones, emphasizing their occurrence in Citrus spp. fruits and juices, on their bioavailability, and their ability to modulate signal cascades and key metabolic enzymes both in vitro and in vivo. Electronic databases including PubMed, Scopus, Web of Science, and SciFinder were used to investigate recent published articles on Citrus spp. in terms of components and bioactivity potentials.

Flavonoids as anticancer therapies: A systematic review of clinical trials

Flavonoids have been proposed as potential chemotherapeutic agents because they are toxic against cancer cells but not harmful to healthy cells. This systematic review analyzed flavonoid effectiveness in human cancer chemotherapy. Overall, 22 phase II and 1 phase III clinical trials (PubMed, Scopus, and Web of Science) that used flavonoids as a single agent or combined with other therapeutics against hematopoietic/lymphoid or solid cancer published by January 2019 were selected for analysis. Flavopiridol was the most commonly used flavonoid (at a dose of 50-mg/m² IV) for all tumor types. Aside from the relatively low rate of complete response (CR) or partial response (PR) with any administration protocol, flavonoids showed higher positive outcomes for hematopoietic and lymphoid tissues (140 patients with CR and 88 with PR among 615 patients in 11 trials) than for solid tumors (4 patients with CR and 21 with PR among 525 patients in 12 trials). However, because of the high variety in administration schedule, more studies are needed to further understand how flavonoids can promote positive outcomes for cancer patients.

Poly(lactic-co-glycolic acid) Nanoparticles Loaded with Callistemon citrinus Phenolics Exhibited Anticancer Properties against Three Breast Cancer Cell Lines

Fruit and vegetable diets rich in phenolic compounds reduce the risk of various cancers and offer multiple other health benefits due to their bioactivity and powerful antioxidant properties. However, the human health benefits of most phenolic compounds are restricted due to their limited aqueous solubility, low absorption, restricted passive cellular efflux, and poor gastrointestinal stability. Nanotechnology has been used to deliver various therapeutic drugs to specific targets overcoming many of the limitations of direct treatments. This study was designed to develop poly(lactic-co-glycolic acid) (PLGA) nanoencapsulated phenolic-rich extracts from Callistemon citrinus and berberine and to evaluate their effectiveness against extremely invasive MDA-MB 231, moderately invasive MCF-10A, and minimally invasive MCF-7 breast cancers. We have achieved about 80% encapsulation of phenolics from C. citrinus. Most encapsulated nanoparticles were polygonal with particles sizes of 200 to 250 nm. Release of phenolics from encapsulation during storage was biphasic during the first week and then levelled off thereafter. Nanoencapsulated phenolics from C. citrinus extract, berberine, and combination of both enhanced their bioactivity against the three breast cancer cell lines by nearly 2-fold. Growth inhibition of cells was a linear curve relative to phenolic concentration, with a maximum inhibition of nearly 100% at 0.1 mg/ml compared to control.

Chemoresistance mechanisms of breast cancer and their countermeasures

Chemoresistance is one of the major challenges for the breast cancer treatment. Owing to its heterogeneous nature, the chemoresistance mechanisms of breast cancer are complicated, and not been fully elucidated. The existing treatments fall short of offering adequate solution to drug resistance, so more effective approaches are desperately needed to improve existing therapeutic regimens. To overcome this hurdle, a number of strategies are being investigated, such as novel agents or drug carriers and combination treatment. In addition, some new therapeutics including gene therapy and immunotherapy may be promising for dealing with the resistance. In this article, we review the mechanisms of chemoresistance in breast cancer. Furthermore, the potential therapeutic methods to overcome the resistance were discussed.

Structure affinity relationship and docking studies of flavonoids as substrates of multidrug-resistant associated protein 2 (MRP2) in MDCK/MRP2 cells

This study was aimed to determine the relationship of flavonoid structures to their affinity for an important efflux transporter, multidrug-resistant associated protein 2 (MRP2). The cellular uptake (CU) of 35 flavonoids was investigated in MRP2 overexpression MDCK/MRP2 cells. Resulting data identified 8 flavonoids as MRP2 substrates based on their high CU_MK with MK-571 in MDCK/MRP2 cells. Also, three substrates showed better CU_MD in MDCK cells than did CU_MRP in MDCK/MRP2 cells. Docking analyses showed a good correlation (R = 0.926, p = 0.003) between efflux-fold of flavonoid substrates and their docking S_scoring with the MRP2 model, indicating consistency between in silico and in vitro approaches. A structure affinity relationship (SAR) study indicated that 3-OH, 5-OH, 6-OH, 3'-OH, and 4'-OCH₃ substituents were favourable while, 8-OCH₃, 2'-OH, 3'-OCH₃, 4'-OH and 5'-OH were unfavourable for flavonoid affinity to MRP2. Our study provides valuable information for dietary application of flavonoids with specific structures for high absorption.

Effects of Black Raspberries and Their Ellagic Acid and Anthocyanin Constituents on Taxane Chemotherapy of Castration-Resistant Prostate Cancer Cells

Cancer patients often use dietary supplements while on therapy, but little is known about interactions of supplements with cancer chemotherapy. Black raspberries (BRB) have anti-cancer effects, but have not been evaluated for interference with chemotherapy for castrate-resistant prostate cancer (CRPC). Here we studied whether BRB and some of their constituents interact with docetaxel and cabazitaxel on CRPC cells in culture and implanted into nude mice. Ellagic acid increased, but BRB extract inhibited, microtubule assembly. Ellagic acid decreased tubulin polymerization by cabazitaxel and bound to tubulin. Ellagic acid, its metabolite urolithin A, BRB extract, and the anthocyanin metabolite protocatechuic acid (PCA) did not alter cytotoxicity of taxanes. Ellagic acid inhibited drug efflux in CRPC cells, but BRB extract and PCA did not. None of these compounds altered CYP3A4 activity. Although dietary ellagic acid did not alter the tumor growth inhibition by docetaxel of xenografted 22Rv1 cells, ellagic acid has the potential to interfere with taxane chemotherapy by reducing tubulin polymerization while inhibiting P-glycoprotein drug efflux. These data are cause for concern of consuming ellagic acid during treatment for CRPC and indicate need for further research, but BRB consumption appears safe.

Enhanced Anti-diabetic Effect of Berberine Combined With Timosaponin B2 in Goto-Kakizaki Rats, Associated With Increased Variety and Exposure of Effective Substances Through Intestinal Absorption

Objective: Inspired by the traditionally clinical application of herb pair Zhimu-Huangbo to treat diabetes, a combination of plant ingredients, timosaponin B2 (TB-2) and berberine (BBR), was evaluated for their anti-diabetic efficacy and cooperative mechanisms.

Methods: The efficacy and pharmacokinetics of orally administered TB-2 (33.3 mg/kg/day), BBR (66.7 mg/kg/day), and TB-2+BBR (100 mg/kg/day) were evaluated in spontaneously non-obese diabetic Goto-Kakizaki (GK) rats, and metformin (200 mg/kg/day) was used as a positive control. The comparative exposure of the parent drugs, timosaponin A3 (TB-2 metabolite), and M1–M5 (BBR metabolites) was quantified in the portal vein plasma (before hepatic disposition), liver, and systemic plasma (after hepatic disposition) of normal rats on single and combination treatments. Cooperative mechanism of TB-2 and BBR on intestinal absorption and hepatic metabolism was investigated in Caco-2 cells and primary hepatocytes, respectively.

Results: After a 6-week experiment, non-fasting and fasting blood glucose levels and oral glucose tolerance test results showed that TB-2+BBR treatments (100 mg/kg/day) displayed significantly anti-diabetic efficacy in GK rats, comparable to that on metformin treatments. However, no significant improvement was observed on TB-2 or BBR treatments alone. Compared to single treatments, combination treatments led to the increased circulating levels of BBR by 107% in GK rats. In normal rats, the hepatic exposure of BBR, timosaponin A3, and M1–M5 was several hundred folds higher than their circulating levels. Co-administration also improved the levels in the plasma and liver by 41–114% for BBR, 141–230% for TB-2, and 12–282% for M1–M5. In vitro, the interaction between TB-2 and BBR was mediated by intestinal absorption, rather than hepatic metabolism.

Conclusion: Combining TB-2 and BBR enhanced the anti-diabetic efficacy by increasing the in vivo variety of effective substances, including the parent compounds and active metabolites, and improving the levels of those substances through intestinal absorption. This study is a new attempt to assess the effects of combined plant ingredients on diabetes by scientifically utilizing clinical experience of an herb pair.

Synthesis of 5-Hydroxy-3',4',7-trimethoxyflavone and Related Compounds and Elucidation of Their Reversal Effects on BCRP/ABCG2-Mediated Anticancer Drug Resistance

3',4',7-Trimethoxyflavone (TMF) has been reported to show a potent reversal effect on drug resistance mediated by breast cancer resistance protein (BCRP)/ATP-binding cassette subfamily G member 2 (ABCG2). In this study, we designed and synthesized five derivatives with either a hydroxy group or a fluorine atom at C-5 and several kinds of capping moiety at the C-7 hydroxy group, on the same 3',4'-dimethoxy-substituted flavone skeleton. We subsequently evaluated the efficacies of these compounds against BCRP-expressing human leukaemia K562/BCRP cells. Reversal of drug resistance was expressed as the concentration of compound causing a twofold reduction in drug sensitivity (RI₅₀ ). Of the synthesized compounds, the reversal effect of 5-hydroxy-3',4',7-trimethoxyflavone (HTMF, RI₅₀ 7.2 nm) towards 7-ethyl-10-hydroxycamptothecin (SN-38) was stronger than that of TMF (RI₅₀ 18 nm). Fluoro-substituted 5-fluoro-3',4',7-trimethoxyflavone (FTMF, RI₅₀ 25 nm) and monoglycosylated 7-(β-glucosyloxy)-5-hydroxy-3',4'-dimethoxyflavone (GOHDMF, 91 nm) also exhibited reversal effects, whereas the di- and triglycoside derivatives did not. TMF, HTMF and FTMF at 0.01-10 μm upregulated the K562/BCRP cellular accumulation of Hoechst 33342 nuclear staining dye. In addition, western blotting revealed that treatment of K562/BCRP cells with 0.1 μm TMF, HTMF or FTMT suppressed the expression of BCRP. HTMF showed the strongest inhibition of BCRP-mediated efflux and suppression of BCRP expression of the three effective synthesized flavones.

A Review of Lignan Metabolism, Milk Enterolactone Concentration, and Antioxidant Status of Dairy Cows Fed Flaxseed

Lignans are polyphenolic compounds with a wide spectrum of biological functions including antioxidant, anti-inflammatory, and anticarcinogenic activities, therefore, there is an increasing interest in promoting the inclusion of lignan-rich foods in humans' diets. Flaxseed is the richest source of the lignan secoisolariciresinol diglucoside-a compound found in the outer fibrous-containing layers of flax. The rumen appears to be the major site for the conversion of secoisolariciresinol diglucoside to the enterolignans enterodiol and enterolactone, but only enterolactone has been detected in milk of dairy cows fed flaxseed products (whole seeds, hulls, meal). However, there is limited information regarding the ruminal microbiota species involved in the metabolism of secoisolariciresinol diglucoside. Likewise, little is known about how dietary manipulation such as varying the nonstructural carbohydrate profile of rations affects milk enterolactone in dairy cows. Our review covers the gastrointestinal tract metabolism of lignans in humans and animals and presents an in-depth assessment of research that have investigated the impacts of flaxseed products on milk enterolactone concentration and animal health. It also addresses the pharmacokinetics of enterolactone consumed through milk, which may have implications to ruminants and humans' health.

The Antitumor Natural Compound Falcarindiol Disrupts Neural Stem Cell Homeostasis by Suppressing Notch Pathway

Neural stem cells (NSCs) are undifferentiated, multi-potent cells that can give rise to functional neurons and glial cells. The disruption in NSC homeostasis and/or the impaired neurogenesis lead to diverse neurological diseases, including depression, dementia, and neurodegenerative disorders. Falcarindiol (FAD) is a polyacetylene found in many plants, and FAD shows the cytotoxicity against breast cancers and colon cancers. However, there is no research on the consequence of FAD treatment in normal stem cells. Here, we suggest that FAD has anticancer roles against glioblastoma cells by inducing the differentiation of glioblastoma stem-like cells, as well as activating apoptosis pathway in glioblastoma cells. On the other hand, we also show that FAD has detrimental effects by disrupting the maintenance of normal NSCs and altering the balance between self-renewal and differentiation of NSCs.

Application of alkaloids in reversing multidrug resistance in human cancers

Multidrug resistance (MDR) in human cancer is one of greatest challenges in cancer therapy. Natural products, especially the alkaloids, exert reversed effects on MDR with low toxicity, by interacting with various targets. In this review article, we summarize the recent progress made in the research of the main alkaloids, including classification, function, mechanism, research status, and application in reversing MDR.

Synergistic combination chemotherapy using carrier-free celastrol and doxorubicin nanocrystals for overcoming drug resistance

A key challenge of chemotherapy in clinical treatments is multidrug resistance (MDR), which mainly arises from drug efflux-induced tumor cell survival. Thus, it is necessary to provide biocompatible chemotherapeutics to improve drug accumulation in MDR cells. Herein, two clinical small molecular drugs, celastrol (CST) and doxorubicin (DOX), were self-assembled into carrier-free and biocompatible nanoparticles (CST/DOX NPs) via a simple and green precipitation method for synergistic combination chemotherapy to overcome DOX resistance. These spherical CST/DOX NPs can improve the water-solubility of CST, reduce the dosage of DOX, and therefore significantly enhance cellular drug accumulation by activating heat shock factor 1 (HSF-1) and inhibiting NF-κB to depress P-gp expression, which results in apoptosis and autophagy of DOX resistant cells through the ROS/JNK signaling pathway. Finally, synergistic combination chemotherapy was attained in both MCF-7/MDR cells and 3D multicellular tumor spheroids. Thus, CST/DOX NPs provide an alternative for overcoming drug resistance in future clinical applications.

By blocking hexokinase-2 phosphorylation, limonin suppresses tumor glycolysis and induces cell apoptosis in hepatocellular carcinoma

Introduction

The purpose of present study was to investigate the effect of limonin on tumor glycolysis and the underlying mechanisms in hepatocellular carcinoma (HCC).

Methods

Cell proliferation and colony formation assays were performed to evaluate the potency of limonin against HCC cells in vitro. The glucose consumption and lactate production after limonin treatment was determined. The effect of limonin on hexokinase-2 (HK-2) activity was assessed and the mitochondrial location of HK-2 was studied by immunoprecipitation. Cell apoptosis and protein expression were detected by flow cytometry and western blotting respectively. Protein overexpression by plasmid transfection was adopted to investigate the molecular mechanisms.

Results

HCC proliferation and colony formation were inhibited by limonin in vitro. With the suppression of HK-2 activity, the glycolytic level in HCC cells was substantially reduced, which was evidenced by the decrease of glucose consumption and lactate production. The phosphorylation of HK-2 was substantially inhibited by limonin, which resulted in the disassociation of HK-2 from mitochondria. Due to the reduction of HK-2 in mitochondria, increasing Bax were shifted to the mitochondria and gave rise to the release of cytochrome C, which induced HCC cells to subject to mitochondria-mediated apoptosis. Mechanism investigations revealed that the decrease of HK-2 phosphorylation was mainly due to the inhibition of Akt activity. In Akt exogenously overexpressed HCC cells, limonin-mediated cell proliferation inhibition, glycolysis suppression and apoptosis induction were significantly impaired.

Conclusion

Limonin inhibited the tumor glycolysis in hepatocellular carcinoma by suppressing HK-2 activity, and the suppression of HK-2 was closely related to the decrease of Akt activity.

Chemopreventive activity of celastrol in drug-resistant human colon carcinoma cell cultures

Celastrol (tripterine) a pentacyclic triterpenoid extracted from the roots of Tripterygium wilfordii Hook f., exhibits potent antioxidant and anti-inflammatory activity and also exerts important anti-cancer effects, as induction of apoptosis and lowering the level of drug resistance of several cancers. Increased level of cellular resistance to cytostatic drugs is typical for colorectal cancers, and largely determines the failure of chemotherapy for this tumor. The purpose of our research was to evaluate the chemopreventive effect of celastrol on cultures of colon cancer cells resistant to doxorubicin (LOVO/DX). With the use of flow cytometry we have shown that celastrol reduces the cell size of the SP (side population; subpopulation of cancer cells enriched with cancer stem cells), increases frequency of apoptosis and binds to Pgp protein in cell membranes inhibiting its transport function. The inhibition of the Pgp transport function has been shown to increase the accumulation of rhodamine-123 and standard cytostatic- doxorubicin in LOVO/DX cells. Our results prove that celastrol exhibits significant chemopreventive and chemosensitizing activities on drug resistant colon cancer cells. Celastrol appears to be a good candidate for adjuvant medicine that can improve the effectiveness of standard cytostatic therapy in humans.

Ursolic acid, a potential anticancer compound for breast cancer therapy

There are growing interests in the health benefits associated with consumption of fruits and vegetables, especially for the prevention of cancer, cardiovascular, or other chronic diseases. Epidemiological studies and clinical trials suggest that these health benefits are strongly associated with phytochemicals found in fruits and vegetables. Ursolic acid is a naturally synthesized pentacyclic triterpenoid, widely distributed in different fruits and vegetables. Current research suggested that ursolic acid and its derivatives exhibited anticancer activity, anti-inflammatory effects, and induction of apoptosis in several human cancer cells. In particular, ursolic acid inhibited breast cancer proliferation by inducing cell G1/G2 arrest and regulating the expression of key proteins in signal transduction pathways. In addition, ursolic acid induced apoptosis in human breast cancer cells through intrinsic and extrinsic apoptotic pathways. Ursolic acid was also determined to scavenge free radicals and have potent anti-inflammation activity. The purpose of this paper is to review recent literature on anticancer activity of ursolic acid and focus on its mechanisms of action.

ABC-transporter blockage mediated by xanthotoxin and bergapten is the major pathway for chemosensitization of multidrug-resistant cancer cells

Furanocoumarins derived from herbal and citrus extracts can act as antibacterial, antioxidant, immunomodulator, apoptotic, and selective anticancer agents, prompting a biological investigation to determine and predict their clinical therapeutic significance. Here, the cell cytotoxic effects of bergapten and xanthotoxin were analyzed alone and in combination with standard chemotherapeutics on three multidrug resistant cells and their nonresistant parental counterparts. The furanocoumarins modulatory effects on MDR1, BCRP, and MRP pump expression and function were investigated. Although quantitative real time PCR demonstrated that the MDR transcript level changes in a time dependent manner, flow cytometric analyses using fluorescent-labeled antibodies have indicated that bergapten and xanthotoxin had no significant effect on the protein levels. FACS analyses indicated that these prominent anticancer agents significantly blocked MDR1, BCRP, and MRP transporter function. Maximum furanocoumarin-mediated pump activity blockage in the MDR-resistant cells was quantified as 87% of normal and consequently, chemotherapeutic accumulation increased up to 2.7-fold and cytotoxicity tension increased 104-fold. MDR1 efflux kinetics also revealed that the maximum velocity and the pump affinity to daunorubicin were uncompetitively decreased. We conclude that bergapten and xanthotoxin are cytotoxic agents capable of preventing daunorubicin, mitoxantrone, and cisplatin binding to ABC-transporters and subsequently inhibiting their efflux out of cells and they may be a potential combination therapy for malignant cancers.