Quercetin potentiates the effect of adriamycin in a multidrug-resistant MCF-7 human breast-cancer cell line: P-glycoprotein as a possible target

Targets Involved in the Anti-Cancer Activity of Quercetin in Breast, Colorectal and Liver Neoplasms

Phytochemicals have long been effective partners in the fight against several diseases, including cancer. Among these, flavonoids are valuable allies for both cancer prevention and therapy since they are known to influence a large panel of tumor-related processes. Particularly, it was revealed that quercetin, one of the most common flavonoids, controls apoptosis and inhibits migration and proliferation, events essential for the development of cancer. In this review, we collected the evidence on the anti-cancer activity of quercetin exploring the network of interactions between this flavonol and the proteins responsible for cancer onset and progression focusing on breast, colorectal and liver cancers, owing to their high worldwide incidence. Moreover, quercetin proved to be also a potentiating agent able to push further the anti-cancer activity of common employed anti-neoplastic agents, thus allowing to lower their dosages and, above all, to sensitize again resistant cancer cells. Finally, novel approaches to delivery systems can enhance quercetin's pharmacokinetics, thus boosting its great potentiality even further. Overall, quercetin has a lot of promise, given its multi-target potentiality; thus, more research is strongly encouraged to properly define its pharmaco-toxicological profile and evaluate its potential for usage in adjuvant and chemoprevention therapy.

The antiproliferative and apoptotic potential of Clinacanthus nutans against human breast cancer cells through targeted apoptosis pathway

Clinacanthus nutans dichloromethane fraction (CN-Dcm) extract has previously been proven to suppress breast cancer (MCF7) cell proliferation. Despite this, the extrinsic and intrinsic apoptosis mechanisms involved in C. nutans extract-treated MCF7 cells are still unknown. This study was intended to subfractionate CN-Dcm extract using column chromatography and analyse the treated MCF7 cells using the CellTiter 96® AQueous One Solution Cell Proliferation (MTS) assay, Annexin V/propidium iodide (PI) assay, western blot, and reverse transcription-qualitative polymerase chain reaction (RT-qPCR). Out of nine subfraction extracts (SF1 to SF9), SF2 extract strongly inhibited MCF7 cells with the lowest IC50 value (23.51 ± 1.00 µg/mL) and substantially induced apoptosis in the MCF7 cells. In treated MCF7 cells, SF2 extract significantly upregulated the expression of P53, BAX, BID, caspase-8, caspase-9, and caspase-3, while downregulating the expression of BCL2. The presence of potential bioactive chemical compounds in the SF2 extract was identified using liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (LC-QTOF-MS). Thus, the SF2 extract has the potential to induce apoptosis in MCF7 cells through intrinsic and extrinsic pathways.

A Recent Review on Bio-availability Enhancement of Poorly Water-soluble Drugs by using Bioenhancer and Nanoparticulate Drug Delivery System

BACKGROUND

Intravenous route of drug administration has maximum bioavailability, which shows 100% of the drug reaches blood circulation, whereas the oral administration of drugs, are readily undergoing pre-systemic metabolism, which means the poor bioavailability of the drug and limited amount of drug reaches the target site.

INTRODUCTION

Bioenhancers are substances having medicinal entities which enhance the bioavailability and efficacy of the active constituents of drugs. The enhanced bioavailability of drugs may lead to dose reduction, which may further reduce the cost and undesired side effects associated with the drugs.

METHODS

The solid lipid nanoparticles (SLNs) loaded with ketoprofen made from carnauba wax and beeswax. It was discovered that when the drug-loaded SLNs were mixed with egg-lecithin and Tween-80, as well as when the total surfactant concentration was increased, the average particle size of the drug-loaded SLNs decreased.

RESULTS

The drug-loaded nanoparticles, when given in combination with bio-enhancers such as piperine and quercetin, enhanced the drug's effectiveness. The Area Under Curve (AUC) was increased when the drug was coupled with bio-enhancers. Based on the findings, it can be concluded that piperine and quercetin when used with drug-loaded nanoparticles improve their therapeutic effectiveness.

CONCLUSION

Bioenhancers are crucial to amplifying the bioavailability of many synthetic drugs. These attributes are useful to reduce the dose of drugs and increase the therapeutic efficacy of drugs with poor bioavailability.

Combination of 7-O-geranylquercetin and microRNA-451 enhances antitumor effect of Adriamycin by reserving P-gp-mediated drug resistance in breast cancer

Although there are a lot of chemical drugs to treat breast cancer, increasing drug resistance of cancer cells has strongly hindered the effectiveness of chemotherapy. ATP-binding cassette transporters represented by P-glycoprotein (P-gp), multidrug resistance associated protein 1 (MRP1) and breast cancer resistance protein (BCRP) play an important role in drug resistance. This study aims to investigate the effect of 7-O-geranylquercetin (GQ) combining microRNA-451(miR-451) on reversing drug resistance of breast cancer and reveal the mechanism related to P-gp. Real-time RT-PCR and western blot assays showed that miR-326, miR-328, miR-451 and miR-155 inhibitor down-regulated the expression of genes MRP1, BCRP, MDR1 and the corresponding proteins MRP1, BCRP, P-gp, respectively. Cell counting kit-8 (CCK-8) assay indicated that these miRNAs reversed the resistance of MCF-7/ADR cells to Adriamycin (ADR), and miR-451 showed the greatest reversal effect. Combination of GQ and miR-451 enhanced the inhibitory effects of ADR on the proliferation and migration of MCF-7/ADR cells, and attenuated the expression of MDR1 and P-gp in MCF-7/ADR cells. A xenograft tumor model was used to show that GQ and miR-451 amplified the antitumor effect of ADR in nude mice, while western blot and immunohistochemical assays revealed the decreased expression of P-gp in tumor tissues. These results suggest that GQ and miR-451 have synergistic effect on reversing drug resistance through reducing the expression of MDR1 and P-gp in breast cancer MCF-7/ADR cells.

Nanoparticles Formulation Improves the Antifibrogenic Effect of Quercetin on an Adenine-Induced Model of Chronic Kidney Disease

Renal fibrosis is the final stage of chronic kidney injury characterized by glomerulosclerosis and tubulointerstitial fibrosis with parenchymal destruction. Quercetin belongs to the most studied flavonoids with antioxidant, anti-inflammatory, antifibrogenic, and antitumor activity. It modifies the TGF-β/Smad signaling pathway, decreasing profibrogenic expression molecules and inducing the expression of antioxidant, anti-inflammatory, and antifibrogenic molecules. However, quercetin exhibits poor water solubility and low absorption and bioavailability. This limitation was solved by developing a nanoparticles formulation that improves the solubility and bioavailability of several bioactive compounds. Therefore, we aimed to investigate the in vivo antifibrogenic effect of a quercetin nanoparticles formulation. Male C57BL/6 mice were induced into chronic renal failure with 50 mg/kg of adenine for four weeks. The animals were randomly grouped and treated with 25, 50, or 100 mg/kg of quercetin, either macroparticles or nanoparticles formulation. We performed biochemical, histological, and molecular analyses to evaluate and compare the effect of macroparticles versus nanoparticles formulation on kidney damage. Here, we demonstrated that smaller doses of nanoparticles exhibited the same beneficial effect as larger doses of macroparticles on preventing kidney damage. This finding translates into less quercetin consumption reaching the desired therapeutic effect.

Advances in heterocycles as DNA intercalating cancer drugs

The insertion of a molecule between the bases of DNA is known as intercalation. A molecule is able to interact with DNA in different ways. DNA intercalators are generally aromatic, planar, and polycyclic. In chemotherapeutic treatment, to suppress DNA replication in cancer cells, intercalators are used. In this article, we discuss the anticancer activity of 10 intensively studied DNA intercalators as drugs. The list includes proflavine, ethidium bromide, doxorubicin, dactinomycin, bleomycin, epirubicin, mitoxantrone, ellipticine, elinafide, and echinomycin. Considerable structural diversities are seen in these molecules. Besides, some examples of the metallo-intercalators are presented at the end of the chapter. These molecules have other crucial properties that are also useful in the treatment of cancers. The successes and limitations of these molecules are also presented.

Christia vespertilionis extract induced antiproliferation and apoptosis in breast cancer (MCF7) cells

BACKGROUND

C. vespertiliomis extracts were evaluated for antiproliferative and apoptosis effect on breast cancer (MCF7) cells.

METHODS AND RESULTS

The leaves extracts were analysed for its antiproliferative effect on breast cancer (MCF7) cells and normal epithelial breast (MCF 10A) cells using Sulforhodamine B (SRB) assay. The selective extract was evaluated for its ability to induce apoptosis using Annexin V-FITC apoptosis staining and the expression of molecular genes using qualitative reverse transcription-polymerase chain reaction (RT-PCR) against MCF7 cells. Gas chromatography-mass spectrometry (GC-MS) was used to identify the compounds from the selective extract. The findings showed that dichloromethane fraction (CV-Dcm) extract had high antiproliferative effect against MCF7 cells (IC₅₀ = 24 µg/mL, selective index (SI) = 8.17). The percentages of apoptosis cells in CV-Dcm-treated MCF7 cells was 58.8%. The CV-Dcm extract induced downregulation of PCNA level. The apoptotic genes were also triggered in both extrinsic and intrinsic signaling pathways, affecting a 1.5-fold increase in BAX, 1.4-fold increase in cytochrome c, 1.3-fold increase in caspase-8, 1.7-fold increase in caspase-3 and 0.5-fold-decrease in BCL-2. Treated MCF7 cells also activated P53-dependent apoptotic death pathway.

CONCLUSIONS

The present work strongly suggests that high efficacy of CV-Dcm extract was attributed to its antiproliferative and apoptosis-inducing activation in MCF7 cells, most likely due to its favourable compounds.

Electrochemical determination of anticancer drug Bendamustine and its interaction with double strand DNA in the absence and presence of quercetin

Studies based on drug-DNA interactions, especially anticancer drug-DNA interactions, are of great importance for the method development. It is thought that single-use electrodes, which give fast, cheap and reproducible results, will make a great contribution to the chip technology for the development of individual patient analysis in the future. It is known that antioxidants reduce carcinogenesis caused by oxidative stress with their radical scavenging effects. Literature shows that quercetin (QRCT) exhibits anticancer activity by preventing oxidative cell damage as an effective radical scavenger. In this study, Bendamustine (BND), an anticancer drug, which is used in different blood cancer types, was electrochemically determined and the toxicity degree was calculated by examining the interaction of the drug with DNA in the absence and presence of QRCT, which is the first examination in the literature. Limit of detection and quantification for BND was calculated as 6.0 and 20.0 μg/mL respectively by using the equation I = 0.029 × C_BND+ 1.197, (R² = 0.997). We found that QRCT prevents the interaction between BND and DNA because of its strong interaction with DNA.

Research Progress in Flavonoids as Potential Anticancer Drug Including Synergy with Other Approaches

BACKGROUND

In chemotherapy for cancer, conventional drugs aim to target the rapidly growing and dividing cells at the early stages. However, at an advanced stage, cancer cells become less susceptible because of the multidrug resistance and the recruitment of alternative salvage pathways for their survival. Besides, owing to target non-selectivity, healthy proliferating cells also become vulnerable to the damage. The combination therapies offered using flavonoids to cure cancer not only exert an additive effect against cancer cells by targetting supplementary cell carnage pathways but also hampers the drug resistance mechanisms. Thus, the review aims to discuss the potential and pharmacokinetic limitations of flavonoids in cancer treatment. Further successful synergistic studies reported using flavonoids to treat cancer has been described along with potential drug delivery systems.

METHODS

A literature search was done by exploring various online databases like Pubmed, Scopus, and Google Scholar with the specific keywords like "Anticancer drugs", "flavonoids", "oncology research", and "pharmacokinetics".

RESULTS

Dietary phytochemicals, mainly flavonoids, hinder cell signalling responsible for multidrug resistance and cancer progression, primarily targeting cancer cells sparing normal cells. Such properties establish flavonoids as a potential candidate for synergistic therapy. However, due to low absorption and high metabolism rates, the bioavailability of flavonoids becomes a challenge. Such challenges may be overcome using novel approaches like derivatization, and single or co-delivery nano-complexes of flavonoids with conventional drugs. These new approaches may improve the pharmacokinetic and pharmacodynamic of flavonoids.

CONCLUSION

This review highlights the application of flavonoids as a potential anticancer phytochemical class in combination with known anti-cancer drugs/nanoparticles. It also discusses flavonoid's pharmacokinetics and pharmacodynamics issues and ways to overcome such issues. Moreover, it covers successful methodologies employed to establish flavonoids as a safe and effective phytochemical class for cancer treatment.

Ameliorating quercetin constraints in cancer therapy with pH-responsive agarose-polyvinylpyrrolidone -hydroxyapatite nanocomposite encapsulated in double nanoemulsion

Despite quercetin (QC) promising features for cancer therapy, low solubility, poor permeability, and short biological half-life time significantly confine its application in cancer therapy. In this study, a novel approach is developed to improve loading efficiency and attain quercetin sustained-release concurrently. In this direction, hydrogel nanocomposite of agarose (AG)-polyvinylpyrrolidone (PVP)-hydroxyapatite (HAp) was loaded with QC. Incorporating HAp nanoparticles in the AG-PVP hydrogel improved the loading efficiency up to 61%. Also, the interactions between nanoparticle, drug, and hydrogel polymers rendered the nanocomposite pH-responsive at acidic conditions and controlled the burst release at neutral conditions. Then, QC-loaded hydrogel was encapsulated into the water in oil in water nanoemulsions to further sustain the drug release. As a result, the pH-responsive release of QC with prolonged-release over 96 h was observed. In more detail, according to the Korsmeyer-Peppas mathematical model, the mechanism of release was anomalous (diffusion-controlled) at pH 7.4 and anomalous transport (dissolution-controlled) at pH 5.4. The presence of all nanocomposite components was confirmed with FTIR analysis, and XRD results approved the incorporation of QC in the fabricated nanocomposite. The homogeneous surface of the nanocomposite in FESEM images showed good compatibility between components. The zeta potential analysis confirmed the good stability of the nanocarriers. Besides, the fabricated AG-PVP-HAp-QC platform showed significant cytotoxicity on MCF-7 cells compared to QC as a free drug (p < 0.001) and to quercetin-loaded AG-PVP (AG-PVP-QC) (p < 0.001) with enhanced apoptosis induction after the addition of HAp. Accordingly, this delivery platform ameliorated loading and sustained-release of QC, as well as its anticancer activity by releasing the drug at an effective therapeutic level over a long period to induce apoptosis. Thus, turning this drug delivery system into a potential candidate for further biomedical applications.

CYP1B1 as a therapeutic target in cardio-oncology

Cardiovascular complications have been frequently reported in cancer patients and survivors, mainly because of various cardiotoxic cancer treatments. Despite the known cardiovascular toxic effects of these treatments, they are still clinically used because of their effectiveness as anti-cancer agents. In this review, we discuss the growing body of evidence suggesting that inhibition of the cytochrome P450 1B1 enzyme (CYP1B1) can be a promising therapeutic strategy that has the potential to prevent cancer treatment-induced cardiovascular complications without reducing their anti-cancer effects. CYP1B1 is an extrahepatic enzyme that is expressed in cardiovascular tissues and overexpressed in different types of cancers. A growing body of evidence is demonstrating a detrimental role of CYP1B1 in both cardiovascular diseases and cancer, via perturbed metabolism of endogenous compounds, production of carcinogenic metabolites, DNA adduct formation, and generation of reactive oxygen species (ROS). Several chemotherapeutic agents have been shown to induce CYP1B1 in cardiovascular and cancer cells, possibly via activating the Aryl hydrocarbon Receptor (AhR), ROS generation, and inflammatory cytokines. Induction of CYP1B1 is detrimental in many ways. First, it can induce or exacerbate cancer treatment-induced cardiovascular complications. Second, it may lead to significant chemo/radio-resistance, undermining both the safety and effectiveness of cancer treatments. Therefore, numerous preclinical studies demonstrate that inhibition of CYP1B1 protects against chemotherapy-induced cardiotoxicity and prevents chemo- and radio-resistance. Most of these studies have utilized phytochemicals to inhibit CYP1B1. Since phytochemicals have multiple targets, future studies are needed to discern the specific contribution of CYP1B1 to the cardioprotective and chemo/radio-sensitizing effects of these phytochemicals.

Modifications of Plasma Membrane Organization in Cancer Cells for Targeted Therapy

Modifications of the composition or organization of the cancer cell membrane seem to be a promising targeted therapy. This approach can significantly enhance drug uptake or intensify the response of cancer cells to chemotherapeutics. There are several methods enabling lipid bilayer modifications, e.g., pharmacological, physical, and mechanical. It is crucial to keep in mind the significance of drug resistance phenomenon, ion channel and specific receptor impact, and lipid bilayer organization in planning the cell membrane-targeted treatment. In this review, strategies based on cell membrane modulation or reorganization are presented as an alternative tool for future therapeutic protocols.

Simultaneous binding mechanism of multiple substrates for multidrug resistance transporter P-glycoprotein

P-glycoprotein (P-gp), a member of ATP-binding cassette (ABC) transporters, is a multidrug resistance pump. Its promiscuous nature is the main cause of multidrug resistance in cancer cells. P-gp can bind multiple drug molecules simultaneously; however, the binding mechanism is still not clear. Furthermore, the upper limit of the number of substrates that can be accommodated by the binding pocket is not fully understood. In this work, we explore the dynamic process of P-gp binding to multiple substrates by using molecular dynamics (MD) simulations. Our results show that P-gp possesses the ability for simultaneous binding, and that the number of substrates has an upper limit. The accommodating ability of P-gp relates to the size of the binding drugs, and conforms to induced fit theory. In the binding process, the residues 339PHE, 982MET and 986GLN are essential. The pocket of P-gp presents strong flexibility and adaptability features according to the mutation results in this work. Drug molecules tend to gather in the pocket during binding, and interactions between these molecules are beneficial to simultaneous binding. These findings provide new insights into the mechanism of the promiscuous nature of P-gp, and may give us a guideline for inhibiting the process of multidrug resistance.

Pharmacological and Therapeutic Properties of Punica granatum Phytochemicals: Possible Roles in Breast Cancer

Background: Pomgranate (Punica granatum) represents a high source of polyphenols with great bioavailability. The role of this fruit in the prevention and treatment of various malignant pathologies has been long time cited in both scientific and non-scientific literature, making thus important to identify its involvement in the pathophysiological processes. The treatment for breast cancer had focused on the inhibition of the mechanisms that governs the estrogen activity. These mechanisms are covered either by the antagonism of the estrogen receptor (ER) or by the inhibition of the estrogen synthesis. Our interest in identifying a bioactive compound rich in polyphenols, which induces both the antagonism of the estrogen receptor, and the inhibition of the estrogen synthesis, revealed us the pomegranate fruit and its derivatives: peel and seeds. Pomegranates' chemical composition include many biological active substances such as flavonols, flavanols, anthocyanins, proanthocyanidins, ellagitannins and gallotannins. Materials and Methods: We performed a review of the scientific literature by using the following keywords: "pomegranate", "breast cancer", "Punica granatum", "pomegranate polyphenols". Our search was performed in the PubMed and Google Scholar databases, and it included only original research written in English from the last 20 years. None of the articles were excluded due to affiliation. A total number of 28 original papers, which mentioned the beneficial activity of pomegranate against breast cancer, were selected. Both clinical and preclinical studies were considered for this review. Results: Recent discoveries pointed out that polyphenols from Punica granatum possess strong anti-cancer activity, exhibited by a variety of mechanisms, such as anti-estrogenic, anti-proliferative, anti-angiogenetic, anti-inflammatory, and anti-metastatic. Pomegranate extracts induced cell cycle arrest in the G0/G1 phase, and induced cytotoxicity in a dose- and time-dependent manner. Moreover, several polyphenols extracted from pomegranate inhibited the invasion potential, migration and viability of breast cancer cells. The effects of pomegranate juice on serum estrogens and other sexual hormones levels were also investigated on two human cohorts. Conclusions: Punica granatum represents a promising area in oncology. The large availability and low cost, associated with the lack of side effects, made from this natural product a great strategy for the management of breast cancer. There are several mechanistic studies in mouse models and in breast cancer cell lines, suggesting the possible pathways through which polyphenols from pomegranate extracts act, but larger and better-controlled studies are necessary in the future. Only two small clinical trials were conducted on humans until now, but their results are contradictory and should be considered preliminary.

Conformers, Properties of the Anticancer Drug Plocabulin, and its Binding Mechanism with p-Glycoprotein: DFT and MD Studies

Plocabulin (PM060184) is a promising new anticancer drug as a microtubule inhibitor. The conformational structure and properties of plocabulin have been studied theoretically. The initial structure was screened by the B3LYP/3-21G* method, and then 32 unique conformations were further optimised with the B3LYP/6-311G* method. The single-point energies were determined at the M06-L/6-311G(2df,p) level. The UV excitation of the most stable plocabulin conformation in methanol was studied by the TD-CAM-B3LYP/6-311G(2df,p) method. High-quality human p-glycoprotein model was obtained through homology modelling. The binding interaction between p-glycoprotein and plocabulin was studied by docking and MD simulation. LEU65, TYR310, ILE340, THR945, PHE983, MET986, and GLN990 were found to be important amino acid residues in the interaction. From a certain perspective, the ‘reverse exclusion’ mechanism of plocabulin with p-glycoprotein was illustrated, and this mechanism provides theoretical guidance for the structural modification of plocabulin and for design of drug’s to avoid p-glycoprotein-mediated drug resistance.

Antileishmanial Activity of Lignans, Neolignans, and Other Plant Phenols

Secondary metabolites (SM) from organisms have served medicinal chemists over the past two centuries as an almost inexhaustible pool of new drugs, drug-like skeletons, and chemical probes that have been used in the "hunt" for new biologically active molecules with a "beneficial effect on human mind and body." Several secondary metabolites, or their derivatives, have been found to be the answer in the quest to search for new approaches to treat or even eradicate many types of diseases that oppress humanity. A special place among SM is occupied by lignans and neolignans. These phenolic compounds are generated biosynthetically via radical coupling of two phenylpropanoid monomers, and are known for their multitarget activity and low toxicity. The disadvantage of the relatively low specificity of phenylpropanoid-based SM turns into an advantage when structural modifications of these skeletons are made. Indeed, phenylpropanoid-based SM previously have proven to offer great potential as a starting point in drug development. Compounds such as Warfarin^® (a coumarin-based anticoagulant) as well as etoposide and teniposide (podophyllotoxin-based anticancer drugs) are just a few examples. At the beginning of the third decade of the twenty-first century, the call for the treatment of more than a dozen rare or previously "neglected" diseases remains for various reasons unanswered. Leishmaniasis, a neglected disease that desperately needs new ways of treatment, is just one of these. This disease is caused by more than 20 leishmanial parasites that are pathogenic to humans and are spread by as many as 800 sandfly species across subtropical areas of the world. With continuing climate changes, the presence of Leishmania parasites and therefore leishmaniasis, the disease caused by these parasites, is spreading from previous locations to new areas. Thus, leishmaniasis is affecting each year a larger proportion of the world's population. The choice of appropriate leishmaniasis treatment depends on the severity of the disease and its form of manifestation. The success of current drug therapy is often limited, due in most cases to requiring long hospitalization periods (weeks to months) and the toxicity (side effects) of administered drugs, in addition to the increasing resistance of the parasites to treatment. It is thus important to develop new drugs and treatments that are less toxic, can overcome drug resistance, and require shorter periods of treatment. These aspects are especially important for the populations of developing countries. It was reported that several phenylpropanoid-based secondary metabolites manifest interesting antileishmanial activities and are used by various indigenous people to treat leishmaniasis. In this chapter, the authors shed some light on the various biological activities of phenylpropanoid natural products, with the main focus being on their possible applications in the context of antileishmanial treatment.

Quercetin acts as a P-gp modulator via impeding signal transduction from nucleotide-binding domain to transmembrane domain

The inherent ability of the cancer cells to resist chemotherapeutic agents is a major challenge in drug discovery. Chemotherapy is one of the most widely used treatment methods for cancer, but due to multidrug resistance (MDR) development in cancer cells, the healing procedure often fails. Various factors impart cancer resistance to cells; among them, P-glycoprotein (P-gp) overexpression is directly linked to MDR in cancer cells. P-gp leads to the efflux of drug molecules to the extracellular space. Several molecules have been reported to inhibit the P-gp activity. Among them, quercetin has revealed a great potential to modulate P-gp activity. However, the mechanistic understanding of quercetin induced modulation is not entirely elucidated. In the present work, we showed that quercetin binds in the interacting region between the transmembrane domain and nucleotide-binding domain out of the three plausible binding sites of P-gp and restrict the conformational change from inward- to outward-facing conformation of P-gp. Due to the absence of the inward-facing structure of human P-gp, we first modeled an inward-facing P-gp structure. Using molecular docking, the interacting residues of P-gp were identified, and the stability and interaction dynamics of the complex were studied using molecular dynamics simulation. Our work reveals the mechanistic understanding of quercetin induced modulation of P-gp and indicates its importance in cancer treatment.Communicated by Ramaswamy H. Sarma.

Quercetin-Amino Acid Conjugates are Promising Anti-Cancer Agents in Drug Discovery Projects

Quercetin is a plant flavonoid with great potential for the prevention and treatment of disease. Despite the curative application of quercetin is hampered by low bioavailability, its core serves as a scaffold for generating more potent compounds with amplified therapeutic window. This review aims to describe recent advances in the improvement of the pharmacokinetic profile of quercetin via the amino acid prodrug approach which offers wide structural diversity, physicochemical and biological properties improvement. According to the findings, conjugation of quercetin with amino acids results in increased solubility, stability, cellular permeability as well as biological activity. In particular quercetin- amino acid conjugates exhibited potent anticancer, MDR-reversal and antibiotic resistance reversal activities. The synthetic pathways and examples of quercetin-amino acid conjugates are considered. Practical considerations and challenges associated with the development of these prodrugs are also discussed. This mini-review covers the literature on quercetin-amino acid conjugates since 2001 when the first thematic work was published.

Naturally Occurring PCSK9 Inhibitors

Genetic, epidemiological and pharmacological data have led to the conclusion that antagonizing or inhibiting Proprotein convertase subtilisin/kexin type 9 (PCSK9) reduces cardiovascular events. This clinical outcome is mainly related to the pivotal role of PCSK9 in controlling low-density lipoprotein (LDL) cholesterol levels. The absence of oral and affordable anti-PCSK9 medications has limited the beneficial effects of this new therapeutic option. A possible breakthrough in this field may come from the discovery of new naturally occurring PCSK9 inhibitors as a starting point for the development of oral, small molecules, to be used in combination with statins in order to increase the percentage of patients reaching their LDL-cholesterol target levels. In the present review, we have summarized the current knowledge on natural compounds or extracts that have shown an inhibitory effect on PCSK9, either in experimental or clinical settings. When available, the pharmacodynamic and pharmacokinetic profiles of the listed compounds are described.

Antioxidant Effects, Antiproliferative Effects, and Molecular Docking of Clinacanthus nutans Leaf Extracts

Clinacanthus nutans is a well-known herb that has been used as an alternative and therapeutic medicine, however more selective C. nutans extracts are needed. In this study, leaves were extracted with 80% methanol and further fractionated with n-hexane, dichloromethane, chloroform, n-butanol, and aqueous residue. Subsequently, the total phenolic content (TPC), total flavonoid content (TFC), antioxidant scavenging activity, and antiproliferative effects on breast cancer (Michigan Cancer Foundation-7 [MCF7]) and normal breast (Michigan Cancer Foundation-10A [MCF 10A]) cells of the extracts were measured. Additionally, molecular docking simulation of the major compounds from C. nutans extracts was conducted. The aqueous residue had the highest TPC and TFC, whereas the crude extract had the highest scavenging activity. Among the extracts, dichloromethane extract (CN-Dcm) was selected as it had the highest selectivity index (SI) (1.48). Then, the chosen extract (CN-Dcm) was proceed for further analysis. The compounds from CN-Dcm were identified using gas chromatography–mass spectrometry (GC-MS). The major compounds from CN-Dcm were further investigated through molecular docking studies. Palmitic acid and linolenyl alcohol were the compounds found in the CN-Dcm extract that exhibited the highest binding affinities with p53-binding protein Mdm-2. These results highlight the potential of C. nutans as a source of anticancer activities.

Alleviation of Multidrug Resistance by Flavonoid and Non-Flavonoid Compounds in Breast, Lung, Colorectal and Prostate Cancer

The aim of the manuscript is to discuss the influence of plant polyphenols in overcoming multidrug resistance in four types of solid cancers (breast, colorectal, lung and prostate cancer). Effective treatment requires the use of multiple toxic chemotherapeutic drugs with different properties and targets. However, a major cause of cancer treatment failure and metastasis is the development of multidrug resistance. Potential mechanisms of multidrug resistance include increase of drug efflux, drug inactivation, detoxification mechanisms, modification of drug target, inhibition of cell death, involvement of cancer stem cells, dysregulation of miRNAs activity, epigenetic variations, imbalance of DNA damage/repair processes, tumor heterogeneity, tumor microenvironment, epithelial to mesenchymal transition and modulation of reactive oxygen species. Taking into consideration that synthetic multidrug resistance agents have failed to demonstrate significant survival benefits in patients with different types of cancer, recent research have focused on beneficial effects of natural compounds. Several phenolic compounds (flavones, phenolcarboxylic acids, ellagitannins, stilbens, lignans, curcumin, etc.) act as chemopreventive agents due to their antioxidant capacity, inhibition of proliferation, survival, angiogenesis, and metastasis, modulation of immune and inflammatory responses or inactivation of pro-carcinogens. Moreover, preclinical and clinical studies revealed that these compounds prevent multidrug resistance in cancer by modulating different pathways. Additional research is needed regarding the role of phenolic compounds in the prevention of multidrug resistance in different types of cancer.

Flavonoids as P-gp Inhibitors: A Systematic Review of SARs

P-glycoprotein, also known as ABCB1 in the ABC transporter family, confers the simultaneous resistance of metastatic cancer cells towards various anticancer drugs with different targets and diverse chemical structures. The exploration of safe and specific inhibitors of this pump has always been the pursuit of scientists for the past four decades. Naturally occurring flavonoids as benzopyrone derivatives were recognized as a class of nontoxic inhibitors of P-gp. The recent advent of synthetic flavonoid dimer FD18, as a potent P-gp modulator in reversing multidrug resistance both in vitro and in vivo, specifically targeted the pseudodimeric structure of the drug transporter and represented a new generation of inhibitors with high transporter binding affinity and low toxicity. This review concerned the recent updates on the structure-activity relationships of flavonoids as P-gp inhibitors, the molecular mechanisms of their action and their ability to overcome P-gp-mediated MDR in preclinical studies. It had crucial implications on the discovery of new drug candidates that modulated the efflux of ABC transporters and also provided some clues for the future development in this promising area.

Bioavailability Enhancement of Poorly Soluble Drugs: The Holy Grail in Pharma Industry

Background:

Bioavailability, one of the prime pharmacokinetic properties of a drug, is defined as the fraction of an administered dose of unchanged drug that reaches the systemic circulation and is used to describe the systemic availability of a drug. Bioavailability assessment is imperative in order to demonstrate whether the drug attains the desirable systemic exposure for effective therapy. In recent years, bioavailability has become the subject of importance in drug discovery and development studies.

Methods:

A systematic literature review in the field of bioavailability and the approaches towards its enhancement have been comprehensively done, purely focusing upon recent papers. The data mining was performed using databases like PubMed, Science Direct and general Google searches and the collected data was exhaustively studied and summarized in a generalized manner.

Results:

The main prospect of this review was to generate a comprehensive one-stop summary of the numerous available approaches and their pharmaceutical applications in improving the stability concerns, physicochemical and mechanical properties of the poorly water-soluble drugs which directly or indirectly augment their bioavailability.

Conclusion:

The use of novel methods, including but not limited to, nano-based formulations, bio-enhancers, solid dispersions, lipid-and polymer-based formulations which provide a wide range of applications not only increases the solubility and permeability of the poorly bioavailable drugs but also improves their stability, and targeting efficacy. Although, these methods have drastically changed the pharmaceutical industry demand for the newer potential methods with better outcomes in the field of pharmaceutical science to formulate various dosage forms with adequate systemic availability and improved patient compliance, further research is required.

Impact of Curcuma longa extract on the expression level of brain transporters in in vivo model

Introduction: Blood brain barrier and multidrug resistance phenomenon are subjects of many investigations. Mainly, because of their functions in protecting the central nervous system (CNS) by blocking the delivery of toxic substances to the brain. This special function has some disadvantages, like drug delivery to the brain in neurodegenerative diseases

Objective: The aim of this study was to examine how natural and synthetic substances affect the expression levels of genes (Mdr1a, Mdr1b, Mrp1, Mrp2, Oatp1a4, Oatp1a5 and Oatp1c1) that encode transporters in the blood-brain barrier.

Methods: cDNA was synthesized from total RNA isolated from rat hippocampus. The expression level of genes was determined using real-time PCR (RT-PCR) method.

Results: Our findings showed that verapamil, as a synthetic substance, caused the greatest reduction of mRNA level of genes studied. The standardized extract of Curcuma longa reduced the expression level for Mrp1 and Mrp2, whereas the increase of mRNA level was observed for Mdr1b, Oatp1a5 and Oatp1c1.

Conclusions: These results suggests that herbal extracts may play an important role in overcoming the blood brain barrier during pharmacotherapy.

Drug Bioavailability Enhancing Agents of Natural Origin (Bioenhancers) that Modulate Drug Membrane Permeation and Pre-Systemic Metabolism

Many new chemical entities are discovered with high therapeutic potential, however, many of these compounds exhibit unfavorable pharmacokinetic properties due to poor solubility and/or poor membrane permeation characteristics. The latter is mainly due to the lipid-like barrier imposed by epithelial mucosal layers, which have to be crossed by drug molecules in order to exert a therapeutic effect. Another barrier is the pre-systemic metabolic degradation of drug molecules, mainly by cytochrome P450 enzymes located in the intestinal enterocytes and liver hepatocytes. Although the nasal, buccal and pulmonary routes of administration avoid the first-pass effect, they are still dependent on absorption of drug molecules across the mucosal surfaces to achieve systemic drug delivery. Bioenhancers (drug absorption enhancers of natural origin) have been identified that can increase the quantity of unchanged drug that appears in the systemic blood circulation by means of modulating membrane permeation and/or pre-systemic metabolism. The aim of this paper is to provide an overview of natural bioenhancers and their main mechanisms of action for the nasal, buccal, pulmonary and oral routes of drug administration. Poorly bioavailable drugs such as large, hydrophilic therapeutics are often administered by injections. Bioenhancers may potentially be used to benefit patients by making systemic delivery of these poorly bioavailable drugs possible via alternative routes of administration (i.e., oral, nasal, buccal or pulmonary routes of administration) and may also reduce dosages of small molecular drugs and thereby reduce treatment costs.

LS. Diverse Targeted Approaches to Battle Multidrug Resistance in Cancer

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The efficacy of successful cancer therapies is frequently hindered by the development of drug resistance in the tumor. The term ‘drug resistance’ is used to illustrate the decreased effectiveness of a drug in curing a disease or alleviating the symptoms of the patient. This phenomenon helps tumors to survive the damage caused by a specific drug or group of drugs. In this context, studying the mechanisms of drug resistance and applying this information to design customized treatment regimens can improve therapeutic efficacy as well as the curative outcome. Over the years, numerous Multidrug Resistance (MDR) mechanisms have been recognized and tremendous effort has been put into developing agents to address them. The integration of data emerging from the elucidation of molecular and biochemical pathways and specific tumor-associated factors has shown tremendous promise within the oncology community for improving patient outcomes. In this review, we provide an overview of the utility of these molecular and biochemical signaling processes as well as tumor-associated factors associated with MDR, for the rational selection of cancer treatment strategies.

An Overview on the Anticancer Activity of Azadirachta indica (Neem) in Gynecological Cancers

In recent years, a wide range of studies have pointed out the importance of nutraceuticals as reservoirs of therapeutic compounds for several diseases, including cancer. This study is centered on the role of some nutraceuticals as anticancer agents and on their efficiency in the oncological gynecological field. Gynecological cancers include cervical, ovarian, and breast neoplasia and these are the major causes of morbidity and mortality in the female population. Cervical neoplasia affects sexually active women aged between 30 and 40 years and is considered the second leading cause of death for women worldwide. Epidemiological studies have shown a strong association of this cancer with human papilloma virus (HPV) infection, independent of any others risk factors. Ovarian cancer represents about 4% of all women’s cancers and breast neoplasia registers 52.8 new cases per 100,000 women annually. Since ancient times, herbal therapies have shown a wide range of beneficial effects and a high potential for safeguarding human health. Azadirachta indica (Neem) is a medicinal plant of Indian origin, a tree with more of 140 isolated compounds and at least 35 biologically active principles that have shown an important influence as tumor suppressors by interfering with the carcinogenesis process. Used for centuries in Asia as a natural remedy for cancer, neem compounds present in bark, leaves, flowers, and seed oil have been shown to possess properties such as chemopreventive capacity, apoptotic activities, immunomodulatory effects, and induction of p53-independent apoptosis. The current study is a systematic literature review based on the anticarcinogenic potential of neem compounds in gynecological cancers.

Taxifolin Resensitizes Multidrug Resistance Cancer Cells via Uncompetitive Inhibition of P-Glycoprotein Function

P-glycoprotein (P-gp) effluxes lots of chemotherapeutic agents and leads to multidrug resistance (MDR) in cancer treatments. The development of P-gp inhibitors from natural products provide a potential strategy for the beneficial clinical outcomes. This study aimed to evaluate the effects of the natural flavonoid taxifolin, luteolin, (-)-gallocatechin, and (-)-catechin on human P-gp activity. The kinetic interactions and underlying mechanisms of taxifolin-mediated transporter inhibition were further investigated. The transporter inhibition ability was evaluated in human P-gp stable expression cells (ABCB1/Flp-InTM-293) by calcein-AM uptake assays. The kinetics study for P-gp inhibition was evaluated by doxorubicin and rhodamine123 efflux assays. The MDR reversal ability of taxifolin were performed by SRB assays to detect the cell viability in sensitive cancer cell line (HeLaS3), and resistant cancer cell line (KB-vin). Cell cycle analysis and ABCB1 real-time RT-PCR were used for mechanical exploration. The results demonstrated that taxifolin decreased ABCB1 expression in a concentration-dependent manner. The function of P-gp was inhibited by taxifolin through uncompetitive inhibition of rhodamine 123 and doxorubicin efflux. The combination of taxifolin significantly resensitized MDR cancer cells to chemotherapeutic agents. These results suggested that taxifolin may be considered as a potential P-gp modulator for synergistic treatment of MDR cancers.

Rheum australe, an endangered high-value medicinal herb of North Western Himalayas: a review of its botany, ethnomedical uses, phytochemistry and pharmacology

Rheum australe (Himalayan Rhubarb) is a multipurpose, endemic and endangered medicinal herb of North Western Himalayas. It finds extensive use as a medicinal herb since antiquity in different traditional systems of medicine to cure a wide range of ailments related to the circulatory, digestive, endocrine, respiratory and skeletal systems as well as to treat various infectious diseases. The remedying properties of this plant species are ascribed to a set of diverse bioactive secondary metabolite constituents, particularly anthraquinones (emodin, chrysophanol, physcion, aloe-emodin and rhein) and stilbenoids (piceatannol, resveratrol), besides dietary flavonoids known for their putative health benefits. Recent studies demonstrate the pharmacological efficacy of some of these metabolites and/or their derivatives as lead molecules for the treatment of various human diseases. Present review comprehensively covers the literature available on R. australe from 1980 to early 2018. The review provides up-to-date information available on its botany for easy identification of the plant, and origin and historical perspective detailing its trade and commerce. Distribution, therapeutic potential in relation to traditional uses and pharmacology, phytochemistry and general biosynthesis of major chemical constituents are also discussed. Additionally, efficient and reproducible in vitro propagation studies holding vital significance in preserving the natural germplasm of the plant and for its industrial exploitation have also been highlighted. The review presents a detailed perspective for future studies to conserve and sustainably make use of this endangered plant species at a commercial scale.

Antioxidants as precision weapons in war against cancer chemotherapy induced toxicity - Exploring the armoury of obscurity

Cancer is the leading cause of mortality worldwide, accounting for almost 13% of deaths in the world. Among the conventional cancer treatments, chemotherapy is most frequently carried out to treat malignant cancer rather than localised lesions which is amenable to surgery and radiotherapy. However, anticancer drugs are associated with a plethora of side effects. Each drug, within every class, has its own set of adverse reactions which may cause patient incompliance and deterioration of the quality of life. One of the major causes of adverse reactions, especially for drugs targeting DNA, is the excessive production of reactive oxygen species (ROS) and subsequent build up of oxidative stress. To curb these undesired side effects, several dietary supplements have been tested, amongst which antioxidants have gained increasing popularity as adjuvant in chemotherapy. However, many oncologists discourage the use of antioxidant rich food supplements because these may interfere with the modalities which kill cancer by generating free radicals. In the present review, all studies reporting concomitant use of several antioxidants with chemotherapy are indiscriminately included and discussed impartially.

The effect of supplementation of thirteen different antioxidants and their analogues as a single agent or in combination with chemotherapy has been compiled in this article. The present review encompasses a total of 174 peer-reviewed original articles from 1967 till date comprising 93 clinical trials with a cumulative number of 18,208 patients, 56 animal studies and 35 in vitro studies. Our comprehensive data suggests that antioxidant has superior potential of ameliorating chemotherapeutic induced toxicity. Antioxidant supplementation during chemotherapy also promises higher therapeutic efficiency and increased survival times in patients.

Anticancer and apoptosis‑inducing effects of quercetin in vitro and in vivo

The present study focused on the elucidation of the putative anticancer potential of quercetin. The anticancer activity of quercetin at 10, 20, 40, 80 and 120 µM was assessed in vitro by MMT assay in 9 tumor cell lines (colon carcinoma CT‑26 cells, prostate adenocarcinoma LNCaP cells, human prostate PC3 cells, pheocromocytoma PC12 cells, estrogen receptor‑positive breast cancer MCF‑7 cells, acute lymphoblastic leukemia MOLT‑4 T‑cells, human myeloma U266B1 cells, human lymphoid Raji cells and ovarian cancer CHO cells). Quercetin was found to induce the apoptosis of all the tested cancer cell lines at the utilized concentrations. Moreover, quercetin significantly induced the apoptosis of the CT‑26, LNCaP, MOLT‑4 and Raji cell lines, as compared to control group (P<0.001), as demonstrated by Annexin V/PI staining. In in vivo experiments, mice bearing MCF‑7 and CT‑26 tumors exhibited a significant reduction in tumor volume in the quercetin‑treated group as compared to the control group (P<0.001). Taken together, quercetin, a naturally occurring compound, exhibits anticancer properties both in vivo and in vitro.

Enhancing Tumor Cell Response to Multidrug Resistance with pH-Sensitive Quercetin and Doxorubicin Conjugated Multifunctional Nanoparticles

Classical chemotherapy uses chemotherapeutic agents as a mainstay of anticancer treatment. However, the development of multidrug resistance to chemotherapy limits the effectiveness of current cancer treatment. Nanosized bioconjugates combining a chemotherapeutic agent with a pharmacological approach may improve the curative effect of chemotherapeutic agents. Herein I addressed this issue by describing the synthesis, and testing of, pH-responsive Fe3O4@SiO2(FITC)-BTN/QUR/DOX multifunctional nanoparticles. The particles were designed to modulate resistance-mediating factors and to potentiate the efficacy of DOX against chemoresistance. The physicochemical properties of the nanoparticles were characterized based on the combination of several techniques: dynamic light scattering (DLS), zeta-potential measurement, Fourier transform infrared spectroscopy (FTIR), electron microscopy techniques (SEM and STEM with EDX) and an in vitro pH-dependent release study. Cellular uptake and cytotoxicity experiments demonstrated enhanced intracellular delivery and retention of nanoparticles in the cytoplasm and efficient reduction of cancer cell viability in drug-resistant lung carcinoma A549/DOX cell lines. This did not affect internalization and viability of an immortalized human lung epithelial cell line BEAS-2B. Moreover, proapoptotic and antiproliferative studies showed that Fe3O4@SiO2(FITC)-BTN/QUR/DOX nanoparticles can promote apoptosis, inhibit tumor cell proliferation, and enhance the chemotherapeutic effects of DOX against multidrug resistance. These results confirm that this multifunctional platform possesses significant synergy between QUR and DOX and is promising for development as an antitumor treatment in cancer therapy.

Quercetin-glutamic acid conjugate with a non-hydrolysable linker; a novel scaffold for multidrug resistance reversal agents through inhibition of P-glycoprotein

Previously, we have reported remarkable effect of a quercetin-glutamic acid conjugate to reverse multidrug resistance (MDR) of cancer cells to a broad spectrum of anticancer agents through inhibition of P-glycoprotein (Pgp)-mediated drug efflux. Due to the hydrolysable nature, MDR-reversal activity of the quercetin conjugate was attributed to its hydrolysis product, quercetin. However, several lines of evidence demonstrated that the intact quercetin-glutamic acid conjugate has stronger MDR-reversal activity than quercetin. In order to evaluate this hypothesis and to identify a novel scaffold for MDR-reversal agents, we prepared quercetin conjugates with a glutamic acid attached at the 7-O position via a non-hydrolysable linker. Pgp inhibition assay, Pgp ATPase assay, and MDR-reversal activity assay were performed, and the non-hydrolysable quercetin conjugates showed significantly higher activities compared with those of quercetin. Unfortunately, the quercetin conjugates were not as effective as verapamil in Pgp-inhibition and thereby reversing MDR, but it is worth to note that the structurally modified quercetin conjugates with a non-cleavable linker showed significantly improved MDR-reversal activity compared with quercetin. Taken together, the quercetin conjugates with appropriate structural modifications were shown to have a potential to serve as a scaffold for the design of novel MDR-reversal agents.

Chemopreventive Agents and Inhibitors of Cancer Hallmarks: May Citrus Offer New Perspectives?

Fruits and vegetables have long been recognized as potentially important in the prevention of cancer risk. Thus, scientific interest in nutrition and cancer has grown over time, as shown by increasing number of experimental studies about the relationship between diet and cancer development. This review attempts to provide an insight into the anti-cancer effects of Citrus fruits, with a focus on their bioactive compounds, elucidating the main cellular and molecular mechanisms through which they may protect against cancer. Scientific literature was selected for this review with the aim of collecting the relevant experimental evidence for the anti-cancer effects of Citrus fruits and their flavonoids. The findings discussed in this review strongly support their potential as anti-cancer agents, and may represent a scientific basis to develop nutraceuticals, food supplements, or complementary and alternative drugs in a context of a multi-target pharmacological strategy in the oncology.

Drug interactions in HIV treatment: complementary & alternative medicines and over-the-counter products

INTRODUCTION

Use of complementary and alternative medicines (CAMs) and over-the-counter (OTC) medications are very common among HIV-infected patients. These products can cause clinically significant drug-drug interactions (DDIs) with antiretroviral (ARV) medications, thereby increasing risk for negative outcomes such as toxicity or loss of virologic control. Areas covered: This article provides an updated review of the different mechanisms by which CAM and OTC products are implicated in DDIs with ARV medications. Expert commentary: Much of the literature published to date involves studies of CAMs interacting with older ARV agents via the cytochrome P450 (CYP450) system. However, the HIV treatment and prevention arsenal is continually evolving. Furthermore, our elucidation of the role of non-CYP450 mediated DDIs with ARV medications is greatly increasing. Therefore, clinicians are well served to understand the various mechanisms and extent by which new ARV therapies may be involved in drug interactions with CAMs and OTC medications.

Further Evolution of Multifunctional Niosomes Based on Pluronic Surfactant: Dual Active Targeting and Drug Combination Properties

The loading of chemotherapics into smart nanocarriers that simultaneously possess more than one useful property for specifically targeting a tumor site improves their therapeutic effectiveness, reducing their side effects. Hence, we proposed a combined approach for the treatment of human breast cancer (BC) consisting of the co-encapsulation of doxorubicin and curcumin or doxorubicin and quercetin into multifunctional niosomes, which results in prolonged blood circulation and an ability to spontaneously accumulate at the tumor site (passive target) and to recognize and bind the tumor cells through dual ligand-receptor interactions (active target). The drug-loaded vesicles showed high stability and good capability of loading doxorubicin and antioxidants alone or in combination. Their diameter was around 400 nm. The drugs released from the vesicles were found to be controlled and sustained for over 24 h, with a strong dependence on the co-presence of the loaded molecules. Transferrin and/or folic acid were conjugated on the external surface of the niosomes as ligands, considerably improving the cellular uptake into MCF-7 and MDA-MB-231 malignant cells when compared with the uptake of nonconjugated samples. In vitro evaluation of anticancer activity demonstrated the strong potential of niosomes loaded with a doxorubicin/curcumin combination as useful devices in breast tumor treatment. These features hold great promise for the development of multifunctional devices that combine several advantages such as biocompatibility, stealth properties, loading capability, and active targeting, moving toward the development of more specific and efficient carriers for personalized tumoral therapy.

New halogenated constituents from Mangifera zeylanica Hook.f. and their potential anti-cancer effects in breast and ovarian cancer cells

ETHNOPHARMACOLOGICAL RELEVENCE

Mangifera zeylanica Hook.f. (Anacardiaceae) is a plant endemic to Sri Lanka. Its bark has been used in traditional and Ayurvedic medicine for the treatment of various diseases including some cancers.

AIM OF THE STUDY

This study was planned to isolate and identify potentially cytotoxic compounds from the bark of M. zeylanica, which may have contributed to its ethno pharmacological use in the treatment of cancer.

MATERIALS AND METHODS

The chloroform extract of M. zeylanica bark which is cytotoxic to breast and ovarian cancer cells was fractionated using column chromatography and preparative reversed phase high performance liquid chromatography to isolate four compounds. Structures of the isolated compounds were elucidated by means of (1)H- and (13)C NMR spectroscopy, and mass spectrometric techniques. Cytotoxic potential of the isolated compounds was tested in MDA-MB-231 (triple negative breast cancer), MCF-7 (estrogen receptor positive breast cancer), SKOV-3 (ovarian epithelial cancer) and MCF-10A (normal mammary epithelial) cells by SRB assay. Human cancer drug target real-time PCR array was carried out to analyze regulation of possible cancer drug target genes in compound 2 treated triple negative breast cancer cells. DPPH radical scavenging and caspase 3 and 7 induction in response to isolated compounds were also studied.

RESULTS

Two new halogenated compounds, bromomangiferic acid (1), and chloromangiferamide (2) along with two known compounds quercetin (3), and catechin (4), were isolated from the bark of Mangifera zeylanica for the first time. Interestingly, chloromangiferamide showed cytotoxicity only to triple negative breast cancer cells [IC50:73.19±0.87µM (24h), 56.29±0.86µM (48h)] with no cytotoxicity to other two cancer cell lines or to normal mammary epithelial cells. Quercetin and catechin were cytotoxic to all three cancer cell lines while bromomangiferic acid had no effect. Chloromangiferamide significantly regulated expression of genes associated with apoptosis, drug metabolism, cell cycle, receptor tyrosine kinase signaling, protein kinases, histone deacetylases, growth factors and receptors, topoisomerases, PI-3 kinases and phosphatases in triple negative breast cancer cells.

CONCLUSION

Selective cytotoxic activity in triple negative breast cancer cells and regulation of some cancer drug target genes by chloromangiferamide indicate that it can be used to develop a potential chemotherapeutic agent for triple negative breast cancer cells.

Synergistic anticancer activity of dietary tea polyphenols and bleomycin hydrochloride in human cervical cancer cell: Caspase-dependent and independent apoptotic pathways

Bleomycin is a chemotherapeutic agent that is frequently used in the treatment of various cancers. Bleomycin causes serious adverse effects via antioxidant defense abnormalities against reactive oxygen species (ROS). However, the current cervical cancer monodrug therapy strategy has failed to produce the expected outcomes; hence, combinational therapies are gaining great interest. Tea polyphenols are also effective antioxidative and chemo-preventive agents. However, the combined effect of tea polyphenol (TPP) and bleomycin (BLM) against cervical cancer remains unknown. In this study, we focused on the potential of TPP on BLM anticancer activity against cervical cancer cells. Cervical cancer cells (SiHa) were treated with various concentrations of TPP, BLM and TPP combined with BLM (TPP-BLM), and their effects on cell growth, intracellular reactive oxygen species, poly-caspase activity, early apoptosis and the expression of caspase-3, caspase-8 and caspase-9, Bcl-2 and p53 were assessed. The MTT assay revealed that the SiHa cells were less sensitive to growth inhibition by TPP treatment compared with both BLM and the combination therapy. Nuclear staining indicated that exposure to TPP-BLM increased the percentage of apoptotic nuclei compared with a mono-agent treatment. Caspase activation assay demonstrated that proportion of early and late apoptotic/secondary necrotic cells was higher in the cells treated with the combination therapy than in those treated with either TPP or BLM alone. The TPP-BLM treatment synergistically induced apoptosis through caspase-3, caspase-8 and caspase-9 activation, Bcl-2 upregulation and p53 overexpression. This study suggests that TPP-BLM may be used as an efficient antioxidant-based combination therapy for cervical cancer.

Suppression of HSP27 increases the anti‑tumor effects of quercetin in human leukemia U937 cells

Quercetin, a natural flavonoid, inhibits the growth of leukemia cells and induces apoptosis. Heat shock protein 27 (HSP27) has been reported to promote the development of leukemia by protecting tumor cells from apoptosis through various mechanisms. The present study investigated the effects of small hairpin (sh)RNA-mediated HSP27 knockdown on the anti-cancer effects of quercetin in U937 human leukemia cells. Cells were transfected with recombinant lentiviral vector pCMV-G-NR-U6-shHSP27 (shHSP27), which expressed shRNA specifically targeting the HSP27 gene, alone or in combination with quercetin. The results showed that shHSP27 and quercetin synergistically inhibited U937 cell proliferation and induced apoptosis by decreasing the Bcl2-to-Bax ratio. Furthermore, this combined treatment significantly suppressed the infiltration of tumor cells and the expression of angiogenesis-associated proteins HIF1α and VEGF. Compared with shHSP27 or quercetin alone, shHSP27 plus quercetin markedly decreased the protein expression of cyclinD1 and thus blocked the cell cycle at G1 phase. The Notch/AKT/mTOR signaling pathway is important in tumor aggressiveness; quercetin plus shHSP27 significantly decreased Notch 1 expression and the phosphorylation levels of the downstream signaling proteins AKT and mTOR. The inhibitory effects of quercetin plus shHSP27 on this pathway may thus have been responsible for the cell cycle arrest, inhibition of proliferations and infiltration as well as enhancement of apoptosis. Therefore, these findings collectively suggested that suppression of HSP27 expression amplified the anti-cancer effects of quercetin in U937 human leukemia cells, and that quercetin in combination with shHSP27 represents a promising therapeutic strategy for human leukemia.