Macrolide Derivatives Research Articles

Sucurchalasins A and B, Sulfur-Containing Heterodimers of a Cytochalasan and a Macrolide from the Endophytic Fungus Aspergillus spelaeus GDGJ-286.

Two sulfur-containing heterodimers of a cytochalasan and a macrolide, sucurchalasins A and B (1 and 2), and four known cytochalasan monomers (3-6), as well as four known macrolide derivatives (7-10), were obtained from the endophytic fungus Aspergillus spelaeus GDGJ-286. Sucurchalasins A and B (1 and 2) are the first cytochalasan heterodimers formed via a thioether bridge between cytochalasan and curvularin macrolide units. Their structures were elucidated by detailed analysis of NMR, LC-MS/MS, and X-ray crystallography. In bioassays, 1 and 2 exhibited cytotoxic effects on A2780 cells, with IC50 values of 3.9 and 8.3 μM, respectively. They also showed antibacterial activities against E. faecalis and B. subtilis with MIC values of 3.1 and 6.3 μg/mL, respectively.

Macrolones target bacterial ribosomes and DNA gyrase and can evade resistance mechanisms.

Growing resistance toward ribosome-targeting macrolide antibiotics has limited their clinical utility and urged the search for superior compounds. Macrolones are synthetic macrolide derivatives with a quinolone side chain, structurally similar to DNA topoisomerase-targeting fluoroquinolones. While macrolones show enhanced activity, their modes of action have remained unknown. Here, we present the first structures of ribosome-bound macrolones, showing that the macrolide part occupies the macrolide-binding site in the ribosomal exit tunnel, whereas the quinolone moiety establishes new interactions with the tunnel. Macrolones efficiently inhibit both the ribosome and DNA topoisomerase in vitro. However, in the cell, they target either the ribosome or DNA gyrase or concurrently both of them. In contrast to macrolide or fluoroquinolone antibiotics alone, dual-targeting macrolones are less prone to select resistant bacteria carrying target-site mutations or to activate inducible macrolide resistance genes. Furthermore, because some macrolones engage Erm-modified ribosomes, they retain activity even against strains with constitutive erm resistance genes.

Relationships between antibiotic exposure and asthma in adults in the United States: results of the National Health and Nutrition Examination Survey between 1999 and 2018.

To investigate the relationship between antibiotic exposure and asthma in adults in the United States. Data was obtained from the National Health and Nutrition Examination Survey (NHANES) conducted between 1999 and 2018. A total of 51,124 participants were included, excluding those who were aged < 20 years, female participants who were pregnant, and individuals who did not complete the prescription medications questionnaire and the medical conditions questionnaire regarding asthma status. Antibiotic exposure was defined as the utilization of antibiotics within the past 30 days, categorized based on the Multum Lexicon Plus therapeutic classification system. Asthma was defined as having a history of asthma or having an asthma attack or wheezing symptoms in the past year. The risk of asthma was found to be 2.557 (95% CI: 1.811, 3.612), 1.547 (95% CI: 1.190, 2.011) and 2.053 (95% CI: 1.344, 3.137) times greater in participants who had used macrolide derivatives, penicillin and quinolones in the past 30 days, respectively, compared with those not using antibiotics. After adjusting for demographic covariates and asthma-related factors, only macrolides derivatives were significantly associated with asthma in the 20-40 and 40-60 age groups. For individuals over 60 years old, quinolones were significantly associated with asthma. The effect of different types of antibiotic with asthma varied in male and female populations. Moreover, higher socioeconomic status, greater BMI, younger age, smoking habits, history of infection, chronic bronchitis, emphysema, and family history of asthma were all identified as risk factors for asthma. Our study indicated that three types of antibiotics were significantly associated with asthma in different subgroups of the population. Therefore, the use of antibiotics should be more strictly regulated.

An Approach to Modify 14-Membered Lactone Macrolide Antibiotic Scaffolds.

A ketolide derivative with (12R)-configuration was obtained via a novel ketene acetal in acidic conditions. The structure of this atypical β-keto ketene acetal intermediate within the macrocyclic system has been determined by NMR and X-ray methods. The use of basic conditions at an elevated temperature yielded new, doubly α,β-unsaturated ketone macrolide derivatives with (4E)-configuration as two conformational isomers of folded-in or folded-out conformations.

Bioequivalence of a Preparation of Tulathromycin in Cattle

Testing the quality of antibacterial pharmaceutical preparations that can be regarded as generic is of utmost importance to ensure sustainable medical practices. Hence, comparative pharmacokinetics studies become necessary. In this trial, a new pharmaceutical preparation of tulathromycin (TTM) was submitted to a bioequivalence test, taking the reference preparation of this macrolide derivative as control i.e., the commercial preparation of TTM containing 100 mg of the drug Pisadrax ® , manufactured by PiSA Agropacuaria S.A. de C.V. and the reference brand of TTM Draxxin ® (Zoetis, Mexico). Twenty-four young steers Charolais/Brahman randomly divided into two groups of twelve animals each, received a single injection of 2.5 mg/kg subcutaneously of either preparation. A validated HPLC-masses analytical technique of plasma concentrations of tulathromycin was used to determine TTM plasma concentrations at fixed intervals for 240 h. The key pharmacokinetic parameters were obtained by compartmental and non-compartmental analysis. Results show that the experimental preparation of tulathromycin (Pisadrax ® ) can be regarded as bioequivalent to the reference one (Draxxin ® ) in steers, given that AUC0-240, MRT, and K½el values from both preparations resulted statistically indistinguishable and with confidence interval &gt; 95%.

Rational prioritization strategy allows the design of macrolide derivatives that overcome antibiotic resistance

Antibiotic resistance is a major threat to global health; this problem can be addressed by the development of new antibacterial agents to keep pace with the evolutionary adaptation of pathogens. Computational approaches are essential tools to this end since their application enables fast and early strategical decisions in the drug development process. We present a rational design approach, in which acylide antibiotics were screened based on computational predictions of solubility, membrane permeability, and binding affinity toward the ribosome. To assess our design strategy, we tested all candidates for in vitro inhibitory activity and then evaluated them in vivo with several antibiotic-resistant strains to determine minimal inhibitory concentrations. The predicted best candidate is synthetically more accessible, exhibits higher solubility and binding affinity to the ribosome, and is up to 56 times more active against resistant pathogens than telithromycin. Notably, the best compounds designed by us show activity, especially when combined with the membrane-weakening drug colistin, against Acinetobacter baumanii, Pseudomonas aeruginosa, and Escherichia coli, which are the three most critical targets from the priority list of pathogens of the World Health Organization.

Anti-Proliferative Potential of Secondary Metabolites from the Marine Sponge Theonella sp.: Moving from Correlation toward Causation.

Marine sponges have been recognized as a rich source of potential anti-proliferative metabolites. Currently, there are two sponge-derived anti-cancer agents (a macrolide and a nucleoside) isolated from the Porifera phylum, suggesting the great potential of this sponge as a rich source for anti-neoplastic agents. To search for more bioactive metabolites from this phylum, we examined the EtOAc extract of Theonella sp. sponge. We isolated seven compounds (1–7), including four 4-methylene sterols (1–4), two nucleosides (5 and 6), and one macrolide (7). Among them, theonellasterol L (1) was identified for the first time, while 5′-O-acetyl-2′-deoxyuridine (5) and 5′-O-acetylthymidine (6) were the first identified deoxyuridine and thymidine derivatives from the sponge Theonella sp. These structures were elucidated based on their spectroscopic data. The anti-proliferation activity of compounds 1–7 against the MCF-7, MDA-MB-231, T-47D, HCT-116, DLD-1, K562, and Molt 4 cancer cell lines was determined. The results indicated that the 14-/15-oxygenated moiety played an important role in the antiproliferative activity and the macrolide derivatives dominated the anti-proliferative effect of the sponge Theonella sp. The in silico analysis, using a chemical global positioning system for natural products (ChemGPS-NP), indicated an anti-proliferative mode of actions (MOA) suggesting the potential applications of the isolated active metabolites as anti-proliferative agents.

Design, synthesis and structure–activity relationships of novel N11-, C12- and C13-substituted 15-membered homo-aza-clarithromycin derivatives against various resistant bacteria

Bacterial infections are still the main significant problem of public health in the world, and their elimination will greatly rely on the discovery of antibacterial drugs. In the processes of our searching for novel macrolide derivatives with excellent activity against sensitive and resistant bacteria, three series of novel N11-, C12- and C13-substituted 15-membered homo-aza-clarithromycin derivatives were designed and synthesized as Series A, B and C by creatively opening the lactone ring of clarithromycin (CAM), introducing various 4-substituted phenyl-1H-1,2,3-triazole side chains at the N11, C12 or C13 position of CAM and macrolactonization. The results from their in vitro antibacterial activity demonstrated that compounds 20c, 20d and 20f displayed not only the most potent activity against S. aureus ATCC25923 with the MIC values of 0.5, 0.5 and 0.5 µg/mL, but also greatly improved activity against B. subtilis ATCC9372 with the MIC values of less than or equal to 0.25, 0.25 and 0.25 µg/mL, respectively. In particular, compound 11g exhibited the strongest antibacterial effectiveness against all the tested resistant bacterial strains and had well balanced activity with the MIC values of 4–8 µg/mL. Further study on minimum bactericidal concentration and kinetics confirmed that compound 11g possessed a bacteriostatic effect on bacterial proliferation. Moreover, the results of molecular docking revealed an potential additional binding force between compound 11g and U790 in addition to the normal binding force of macrolide skeleton, which may explain why this compound performed the most potent activity against resistant bacteria. The results of cytotoxic assay indicated that compounds 20c, 20d and 20f were non-toxic to human breast cancer MCF-7 cells at its effective antibacterial concentration.

Truncated Actin-Targeting Macrolide Derivative Blocks Cancer Cell Motility and Invasion of Extracellular Matrix.

Cancer metastasis is a complex process involving highly motile tumor cells that breach tissue barriers, enter the bloodstream and lymphatic system, and disseminate throughout the body as circulating tumor cells. The primary cellular mechanism contributing to these critical events is the reorganization of the actin cytoskeleton. Mycalolide B (MycB) is an actin-targeting marine macrolide that can suppress proliferation, migration, and invasion of breast and ovarian cancer cells at low nanomolar doses. Through structure-activity relationship studies focused on the actin-binding tail region (C24-C35) of MycB, we identified a potent truncated derivative that inhibits polymerization of G-actin and severs F-actin by binding to actin's barbed end cleft. Biological analyses of this miniature MycB derivative demonstrate that it causes a rapid collapse of the actin cytoskeleton in ovarian cancer cells and impairs cancer cell motility and invasion of the extracellular matrix (ECM) by inhibiting invadopodia-mediated ECM degradation. These studies provide essential proof-of-principle for developing actin-targeting therapeutic agents to block cancer metastasis and establish a synthetically tractable barbed end-binding pharmacophore that can be further improved by adding targeting groups for precision drug design.

Isolation and Molecular Docking of Cytotoxic Secondary Metabolites from Two Red Sea Sponges of the Genus Diacarnus

AbstractChemical investigation of methanol extracts from two Jordanian marine sponges belonging to genus Diacarnus: D. erythraeanus and D. ardoukobae (family Podospongiidae) afforded a series of norterpene cyclic peroxides namely; muqubilone A (1), sigmosceptrellin‐B (2), sigmosceptrellin‐B methyl ester (3), (+)‐methyl‐2‐epinuapapuanoate (4); (−)‐methyl‐2‐epinuapapuanoate (5) in addition to a macrolide derivative: latrunculin B (6). Chemical structures of isolated compounds were elucidated based on their 1D and 2D NMR and mass spectra as well as by comparison with the literature. All isolated compounds were assessed for their cytotoxic activity against the murine lymphoma (L5178Y) cell line. Among tested compounds, only (2–4) displayed significant cytotoxicity with IC50 values ranging from 1.2 to 6.4 μM. Molecular docking studies of isolated compounds suggested potential EGFR inhibition and the correlation between docking scores and biological data was strong based on Pearson's correlation coefficient (r=0.93).

Conformational analysis and QSAR modeling of 14-membered macrolide analogues against mycobacterium tuberculosis

Electronic structures, effect of the substitution and structure physical-chemistry properties relationship for macrolide derivatives, have been studied by PM3 and ab initio methods. In the present work, the calculated values, namely net charges, bond lengths, MESP, dipole moments, electron-affinities, heats of formation, then, we treated the structural, physical and chemical relationships for a series of macrolide derivatives with inhibition activity against Mycobacterium tuberculosis. QSAR studies were done for these macrolide derivatives using a combination of various physicochemical descriptors. A multiple linear regression procedure was used to design the relationships between molecular descriptor and the activity of macrolide derivatives. Results validate the derived QSAR model.

Experimental Evaluation of Chronic Toxicity of Amphamide – a New Semisynthetic Derivative of Amphotericin B

Amphotericin B (AmB) remains a drug of first choice for treatment of most severe mycoses despite significant toxicity and solubility problems. Screening of a series of new semisynthetic polyene macrolide derivatives identified AmB N-(2-aminoethyl)amide (amphamide) as having several competitive advantages over the parent polyene. Aprototype parenteral amphamide dosage form in which the active ingredient was highly soluble and stable during storage was developed. Chronic toxicity of the finished amphamide dosage form was studied in rabbits. The amphamide dosage form displayed dose-dependent reversible toxicity.

Influence of glyceryl behenate, tripalmitin and stearic acid on the properties of clarithromycin incorporated solid lipid nanoparticles (SLNs): Formulation, characterization, antibacterial activity and cytotoxicity

Clarithromycin (CLR) is a macrolide derivative which is included in BCS class 2 with low oral bioavailability. Solid lipid nanoparticles (SLNs) have been studied by many researchers for drug application and are very popular systems that continue to be studied. However, the effects of lipids used in SLN production on the formulation properties are one of the few studied topics. Therefore, the aim of this study was to formulate CLR incorporated SLN formulations by ‘high-speed homogenization technique’’ for oral administration and also elucidate the effect of three types of lipid matrix on particle size (PS), polydispersity index (PDI), drug content, release properties etc. For this reason, three types of major lipid matrix (Glyceryl behenate, Tripalmitin and Stearic acid) were chosen in this study. Seven different formulations were characterized in detail and the results were discussed. The PSs of the CLR incorporated SLNs were between 318 and 526 nm. The average PDI of blank nanoparticles varied between 0.211 and 0.409, whereas the average PDI of CLR incorporated SLNs were between 0.228 and 0.472. The drug content was a range of 63–89%. In vitro release studies of SLNs showed extended-release up to 48 h after the first 6 h of burst effect. Both the burst effect kinetics and the 48-h release kinetics were investigated. The results showed that the burst effect was fitted to the Korsmeyer-Peppas model and 48 h to the Baker-Lonsdale model. The structures of the formulations were clarified by DSC & FT-IR analysis. The results showed that PS, PDI, drug content and release rates of SLNs were directly related to the carbon chain length of lipid. Antibacterial activity of the formulations was tested against Staphylococcus aureus by microdilution and agar well diffusion methods. Formulations A3, A5, A6 and A7 rendered CLR, 2 times more effective against its target according to the microdilution method. As for the agar well method, clear zones around A3, A5, A6, and A7 wells were the same size or larger than clarithromycin zone. The cell viability test was performed with MTT in the NIH 3T3 mouse embryonic fibroblast cell line. At the end of the incubation times, no cell viability differences were observed between CLR and formulations. As a result, in vitro characterization and release data demonstrated the possibility of improved bioavailability of CLR by SLN formulation and the effect of lipid used in this study on formulation characteristics were elucidated in detail. At least in terms of some formulations, improved pharmacodynamic effects were also obtained from antibacterial activity studies.

Macrolide derivatives reduce proinflammatory macrophage activation and macrophage-mediated neurotoxicity.

SummaryIntroductionAzithromycin (AZM) and other macrolide antibiotics are applied as immunomodulatory treatments for CNS disorders. The immunomodulatory and antibiotic properties of AZM are purportedly independent.AimsTo improve the efficacy and reduce antibiotic resistance risk of AZM‐based therapies, we evaluated the immunomodulatory and neuroprotective properties of novel AZM derivatives. We semisynthetically prepared derivatives by altering sugar moieties established as important for inhibiting bacterial protein synthesis. Bone marrow‐derived macrophages (BMDMs) were stimulated in vitro with proinflammatory, M1, stimuli (LPS + INF‐gamma) with and without derivative costimulation. Pro‐ and anti‐inflammatory cytokine production, IL‐12 and IL‐10, respectively, was quantified using ELISA. Neuron culture treatment with BMDM supernatant was used to assess derivative neuroprotective potential.ResultsAzithromycin and some derivatives increased IL‐10 and reduced IL‐12 production of M1 macrophages. IL‐10/IL‐12 cytokine shifts closely correlated with the ability of AZM and derivatives to mitigate macrophage neurotoxicity.ConclusionsSugar moieties that bind bacterial ribosomal complexes can be modified in a manner that retains AZM immunomodulation and neuroprotection. Since the effects of BMDMs in vitro are predictive of CNS macrophage responses, our results open new therapeutic avenues for managing maladaptive CNS inflammation and support utilization of IL‐10/12 cytokine profiles as indicators of macrophage polarization and neurotoxicity.

Novel Production of Two New Nonpolyenic Antifungal Macrolide Derivatives by Streptomyces Z26 Isolated from Moroccan Rhizospheric Soil

The aim of our study was to screen Moroccan actinomycete isolates able to produce nonpolyenic antifungal metabolites in order to contribute to limiting the problem of fungal infections emergence in particular mycotic diseases and to discover known antifungal families, especially nonpolyenic drugs. 480 isolates were tested against 5clinically pathogenic Candida species. Several methods have been used to study the polyenic or non-polyenic nature of the antifungal molecules produced by Actinobacteria (i) The study of the antibacterial activity (the bacterial plasma membrane is devoid of sterols); (ii) The screening of the antimicrobial activity of resistant strains to polyenic antifungals essentially Candida tropicalis R2 and Pythium irregular; (iii) The inhibition of antifungal activity by exogenous ergosterol addition in the culture medium and (iv) The UV-Visible light spectrophotometric analysis of the crude extracts of the actinomycete isolates. Among all isolate tested, only 60 (29 %) showed an antifungal activity against all test microorganisms used. Six active isolates meet all the selection criteria and produced nonpolyenic antifungal metabolites. The taxonomic study of the promising isolate Z26, using morphological, physiological and molecular characters, showed that it has 99,43% of similarity with Streptomyces phytohabitans but there were some differences in morphological characteristics. In addition, the chemical study, using chromatographic and spectroscopic techniques, of the bioactive substances produced in the Z26 isolate fermentation broth in NL300 culture medium allowed the determination of two macrolide derivatives with chemical structures C62H100O24(m/z 1251.6504 [M+Na]+) and C68H110O26(m/z 1365.7174 [M+Na]+). NMR experiments revealed that the active compounds were Novonestmycin A and B. The Novonestmycins A and B are for the first time produced by an actinomycete strain purely isolated from the Moroccan ecosystems.

Development of Transcription Factor-Based Designer Macrolide Biosensors for Metabolic Engineering and Synthetic Biology.

Macrolides are a large group of natural products that display broad and potent biological activities and are biosynthesized by type I polyketide synthases (PKSs) and associated enzymatic machinery. There is an urgent need to access macrolides and unnatural macrolide derivatives for drug discovery, drug manufacture, and probe development. Typically, efforts to engineer the biosynthesis of macrolides and macrolide analogues in various microbial hosts are hampered by the complexity of macrolide biosynthetic pathways and our limited ability to rationally reprogram type I PKSs and post-PKS machinery. High-throughput approaches based on synthetic biology and directed evolution could overcome this problem by testing the function of large libraries of variants. Yet, methods that can identify mutant enzymes, pathways, and strains that produce the desired macrolide target are not generally available. Here we show that the promiscuous macrolide sensing transcription factor MphR is a powerful platform for engineering variants with tailored properties. We identified variants that displayed improved sensitivity toward erythromycin, tailored the inducer specificity, and significantly improved sensitivity to macrolides that were very poor inducers of the wild-type MphR biosensor. Designer macrolide biosensors should find broad utility and enable applications related to high-throughput synthetic biology and directed evolution of macrolide biosynthesis.

The macrolide antibiotic renaissance

Macrolides represent a large family of protein synthesis inhibitors of great clinical interest due to their applicability to human medicine. Macrolides are composed of a macrocyclic lactone of different ring sizes, to which one or more deoxy-sugar or amino sugar residues are attached. Macrolides act as antibiotics by binding to bacterial 50S ribosomal subunit and interfering with protein synthesis. The high affinity of macrolides for bacterial ribosomes, together with the highly conserved structure of ribosomes across virtually all of the bacterial species, is consistent with their broad-spectrum activity. Since the discovery of the progenitor macrolide, erythromycin, in 1950, many derivatives have been synthesised, leading to compounds with better bioavailability and acid stability and improved pharmacokinetics. These efforts led to the second generation of macrolides, including well-known members such as azithromycin and clarithromycin. Subsequently, in order to address increasing antibiotic resistance, a third generation of macrolides displaying improved activity against many macrolide resistant strains was developed. However, these improvements were accompanied with serious side effects, leading to disappointment and causing many researchers to stop working on macrolide derivatives, assuming that this procedure had reached the end. In contrast, a recent published breakthrough introduced a new chemical platform for synthesis and discovery of a wide range of diverse macrolide antibiotics. This chemical synthesis revolution, in combination with reduction in the side effects, namely, 'Ketek effects', has led to a macrolide renaissance, increasing the hope for novel and safe therapeutic agents to combat serious human infectious diseases.

Macrolides selectively inhibit mutant KCNJ5 potassium channels that cause aldosterone-producing adenoma.

Aldosterone-producing adenomas (APAs) are benign tumors of the adrenal gland that constitutively produce the salt-retaining steroid hormone aldosterone and cause millions of cases of severe hypertension worldwide. Either of 2 somatic mutations in the potassium channel KCNJ5 (G151R and L168R, hereafter referred to as KCNJ5MUT) in adrenocortical cells account for half of APAs worldwide. These mutations alter channel selectivity to allow abnormal Na+ conductance, resulting in membrane depolarization, calcium influx, aldosterone production, and cell proliferation. Because APA diagnosis requires a difficult invasive procedure, patients often remain undiagnosed and inadequately treated. Inhibitors of KCNJ5MUT could allow noninvasive diagnosis and therapy of APAs carrying KCNJ5 mutations. Here, we developed a high-throughput screen for rescue of KCNJ5MUT-induced lethality and identified a series of macrolide antibiotics, including roxithromycin, that potently inhibit KCNJ5MUT, but not KCNJ5WT. Electrophysiology demonstrated direct KCNJ5MUT inhibition. In human aldosterone-producing adrenocortical cancer cell lines, roxithromycin inhibited KCNJ5MUT-induced induction of CYP11B2 (encoding aldosterone synthase) expression and aldosterone production. Further exploration of macrolides showed that KCNJ5MUT was similarly selectively inhibited by idremcinal, a macrolide motilin receptor agonist, and by synthesized macrolide derivatives lacking antibiotic or motilide activity. Macrolide-derived selective KCNJ5MUT inhibitors thus have the potential to advance the diagnosis and treatment of APAs harboring KCNJ5MUT.

SAFETY SIGNAL DETECTION OF CARDIAC DISORDERS ADVERSE DRUG EVENTS FOR AZITHROMYCIN IN PEDIATRIC POPULATION USING HEALTH CANADA ADVERSE EVENT REPORTING SYSTEM DATABASE

Objective: We conducted signal detection of adverse drug events reported in Health Canada adverse event reporting system database “MedEffect” for azithromycin, a macrolide derivative and the first azalide antimicrobial agent to review the cardiac disorders adverse drug events (ADEs) in pediatric population with the drug labels of selected countries including India, USA, UK, Canada, Switzerland, Australia, New Zealand.Methods: We extracted data between January 1965 and June 2016 from the Canada adverse event reporting system database “MedEffect”. Frequentist and Bayesian methods were used to calculate disproportionality distribution of drug-adverse event (AE) pairs. The AE which was detected by all the three indices of proportional reporting ratio (PRR), reporting odds ratio (ROR), and information component (IC) was identified as a potential signal. AE reports for azithromycin, among which 3651 reports were attributed to paediatrics.Results: The signal detected by PRR and ROR for tachycardia associated with azithromycin were found to be 1.3 and for cardiovascular disorder were 1.2. The IC for azithromycin by a Bayesian method was 0.3 for both, tachycardia and cardiovascular disorder. Both AEs of cardiovascular disorder and tachycardia were detected as potential signals of azithromycin for the paediatric population. Comparing drug labels of 7 countries in paediatric population, both adverse events were not listed on any of the labels of seven countries against the pediatric population.Conclusion: We detected 2 new potential signals of azithromycin which were not listed on the labels of 7 countries. Therefore, it should be accompanied by a signal evaluation including causal association, clinical significance, and preventability.

Hyaluronic Acid Nanohydrogel Loaded With Quercetin Alone or in Combination to a Macrolide Derivative of Rapamycin RAD001 (Everolimus) as a New Treatment for Hormone-Responsive Human Breast Cancer.

The aim of this study is based on the evaluation of anticancer, anti-inflammatory activities, and cellular uptake of hyaluronic acid nanohydrogel of quercetin tested alone and in combination to a macrolide derivative of rapamycin RAD001 (everolimus) on hormone-responsive breast cancer cell line MCF-7. Biological investigations were focused on the receptor mediated cellular internalization of the nanohydrogel and its abilities to reduce secretion of several cytokines (IL-8, IL-6, IL-19), VEGF, and metalloproteases (MMP-2, MMP-9) under pro-inflammatory conditions. Nanohydrogel show a CD44 dependent endocytosis with evident time dependent cytoplasmatic accumulation with abilities to reduce secretion of all cytokines of ∼60% compared to untreated cells. Combination of formulated quercetin and everolimus leads to a synergistic cytotoxic effects with a Combination Index of 0.38. These results highlights the importance of synergistic effect of the hyaluronic acid nanohydrogel of quercetin with everolimus in the regulation of human breast cancer cell proliferation and emphasize the antitumor and anti-inflammatory properties of the nanocarrier. J. Cell. Physiol. 232: 2063-2074, 2017. © 2016 Wiley Periodicals, Inc.