Improvement of conventional anti-cancer drugs as new tools against multidrug resistant tumors

Multidrug resistance (MDR) is the dominant cause of the failure of cancer chemotherapy. The design of antitumor drugs that are able to evade MDR is rapidly evolving, showing that this area of biomedical research attracts great interest in the scientific community. The current review explores promising recent approaches that have been developed with the aim of circumventing or overcoming MDR. Encouraging results have been obtained in the investigation of the MDR-modulating properties of various classes of natural compounds and their analogues. Inhibition of P-gp or downregulation of its expression have proven to be the main mechanisms by which MDR can be surmounted. The use of hybrid molecules that are able to simultaneously interact with two or more cancer cell targets is currently being explored as a means to circumvent drug resistance. This strategy is based on the design of hybrid compounds that are obtained either by merging the structural features of separate drugs, or by conjugating two drugs or pharmacophores via cleavable/non-cleavable linkers. The approach is highly promising due to the pharmacokinetic and pharmacodynamic advantages that can be achieved over the independent administration of the two individual components. However, it should be stressed that the task of obtaining successful multivalent drugs is a very challenging one. The conjugation of anticancer agents with nitric oxide (NO) donors has recently been developed, creating a particular class of hybrid that can combat tumor drug resistance. Appropriate NO donors have been shown to reverse drug resistance via nitration of ABC transporters and by interfering with a number of metabolic enzymes and signaling pathways. In fact, hybrid compounds that are produced by covalently attaching NO-donors and antitumor drugs have been shown to elicit a synergistic cytotoxic effect in a variety of drug resistant cancer cell lines. Another strategy to circumvent MDR is based on nanocarrier-mediated transport and the controlled release of chemotherapeutic drugs and P-gp inhibitors. Their pharmacokinetics are governed by the nanoparticle or polymer carrier and make use of the enhanced permeation and retention (EPR) effect, which can increase selective delivery to cancer cells. These systems are usually internalized by cancer cells via endocytosis and accumulate in endosomes and lysosomes, thus preventing rapid efflux. Other modalities to combat MDR are described in this review, including the pharmaco-modulation of acridine, which is a well-known scaffold in the development of bioactive compounds, the use of natural compounds as means to reverse MDR, and the conjugation of anticancer drugs with carriers that target specific tumor-cell components. Finally, the outstanding potential of in silico structure-based methods as a means to evaluate the ability of antitumor drugs to interact with drug transporters is also highlighted in this review. Structure-based design methods, which utilize 3D structural data of proteins and their complexes with ligands, are the most effective of the in silico methods available, as they provide a prediction regarding the interaction between transport proteins and their substrates and inhibitors. The recently resolved X-ray structure of human P-gp can help predict the interaction sites of designed compounds, providing insight into their binding mode and directing possible rational modifications to prevent them from becoming P-gp drug substrates. In summary, although major efforts were invested in the search for new tools to combat drug resistant tumors, they all require further implementation and methodological development. Further investigation and progress in the abovementioned strategies will provide significant advances in the rational combat against cancer MDR

Designing new antitubercular isoniazid derivatives with improved reactivity and membrane trafficking abilities

Funding Information: We acknowledge Diogo Vila Vi?osa for valuable discussions. We acknowledge financial support from Funda??o para a Ci?ncia e a Tecnologia, Portugal through projects PTDC/MED-QUI/29036/2017, PTDC/BIA-MIC-30692/2017, UIDB/00100/2020, UIDP/00100/2020, UIDB/04046/2020, UIDP/04046/2020, and UID/Multi/04413/2020, and Grants CEECIND/02300/2017 and DL57/CEECIND/0256/2017. Contributions from JRK, CMB, and DCG supported in part by a grant from the National Science Foundation, USA (MCB 1616059). Funding Information: We acknowledge Diogo Vila Viçosa for valuable discussions. We acknowledge financial support from Fundação para a Ciência e a Tecnologia , Portugal through projects PTDC/MED-QUI/29036/2017 , PTDC/BIA-MIC-30692/2017 , UIDB/00100/2020 , UIDP/00100/2020 , UIDB/04046/2020 , UIDP/04046/2020 , and UID/Multi/04413/2020 , and Grants CEECIND/02300/2017 and DL57/CEECIND/0256/2017 . Contributions from JRK, CMB, and DCG supported in part by a grant from the National Science Foundation , USA ( MCB 1616059 ). Publisher Copyright: © 2021 The AuthorsIsoniazid (INH) is one of the two most effective first-line antitubercular drugs and is still used at the present time as a scaffold for developing new compounds to fight TB. In a previous study, we have observed that an INH derivative, an hydrazide N′-substituted with a C10acyl chain, was able to counterbalance its smaller reactivity with a higher membrane permeability. This resulted in an improved performance against the most prevalent Mycobacterium tuberculosis (Mtb) resistant strain (S315T), compared to INH. In this work, we have designed two new series of INH derivatives (alkyl hydrazides and hydrazones) with promising in silico properties, namely membrane permeabilities and spontaneous IN* radical formation. The kinetics, cytotoxicity, and biological activity evaluations confirmed the in silico predictions regarding the very high reactivity of the alkyl hydrazides. The hydrazones, on the other hand, showed very similar behavior compared to INH, particularly in biological tests that take longer to complete, indicating that these compounds are being hydrolyzed back to INH. Despite their improved membrane permeabilities, the reactivities of these two series are too high, impairing their overall performance. Nevertheless, the systematic data gathered about these compounds have showed us the need to find a balance between lipophilicity and reactivity, which is paramount to devise better INH-based derivatives aimed at circumventing Mtb resistance.publishersversionpublishe

Glucosylpolyphenols as Inhibitors of Aβ-Induced Fyn Kinase Activation and Tau Phosphorylation: Synthesis, Membrane Permeability, and Exploratory Target Assessment within the Scope of Type 2 Diabetes and Alzheimer's Disease

Despite the rapidly increasing number of patients suffering from type 2 diabetes, Alzheimer's disease, and diabetes-induced dementia, there are no disease-modifying therapies that are able to prevent or block disease progress. In this work, we investigate the potential of nature-inspired glucosylpolyphenols against relevant targets, including islet amyloid polypeptide, glucosidases, and cholinesterases. Moreover, with the premise of Fyn kinase as a paradigm-shifting target in Alzheimer's drug discovery, we explore glucosylpolyphenols as blockers of Aβ-induced Fyn kinase activation while looking into downstream effects leading to Tau hyperphosphorylation. Several compounds inhibit Aβ-induced Fyn kinase activation and decrease pTau levels at 10 μM concentration, particularly the per-O-methylated glucosylacetophloroglucinol and the 4-glucosylcatechol dibenzoate, the latter inhibiting also butyrylcholinesterase and β-glucosidase. Both compounds are nontoxic with ideal pharmacokinetic properties for further development. This work ultimately highlights the multitarget nature, fine structural tuning capacity, and valuable therapeutic significance of glucosylpolyphenols in the context of these metabolic and neurodegenerative disorders.European Commission GA 612347Fundação para a Ciência e a Tecnologia SFRH/BD/93170/2013, SFRH/BD/116614/2016, PD/BD/142847/2018, SFRH/BD/145600/2019, CEECIND/03414/2018, CEECIND/02300/2017, UIDB/00100/2020, UIDB/04046/2020, UIDB/04378/2020, IF/00780/2015Gobierno de España CTQ2016-78703-PJunta de Andalucía FQM13

Tuning the bioactivity of tensioactive deoxy glycosides to structure: antibacterial activity versus selective cholinesterase inhibition rationalized by molecular docking

New octyl/dodecyl 2,6-dideoxy-D-arabino-hexopyranosides have been synthesized by a simple but efficient methodology based on the reaction of glycals with alcohols catalysed by triphenylphosphane hydrobromide, deprotection, regioselective tosylation and reduction. Their surface-active properties were evaluated in terms of adsorption and aggregation parameters and compared with those of 2-deoxy-D-glycosides and 2,6-dideoxy-L-glycosides. Deoxygenation at the 6-position led to a decrease in the critical micelle concentration, and an increase in the adsorption efficiency (pC20) promoting aggregation more efficiently than adsorption. With regard to the antibacterial activity, dodecyl 2,6-dideoxy-α-L-arabino-hexopyranoside was the most active compound towards Bacillus anthracis (MIC 25 μM), whereas its enantiomer exhibited a MIC value of 50 μM. Both 2,6-dideoxy glycosides were active towards Bacillus cereus, Bacillus subtilis, Enterococcus faecalis and Listeria monocytogenes. In contrast, none of the 2-deoxy glycosides was significantly active. These results and the data on surface activity suggest that aggregation is a key issue for antimicrobial activity. Beyond infection, Alzheimer’s disease also threatens elderly populations. In the search for butyrylcholinesterase (BChE) selective inhibition, 2- deoxy glycosides were screened in vitro by using Ellman’s assay. Octyl 2-deoxy-α-D-glycoside was found to be a BChE selective inhibitor promoting competitive inhibition. Docking studies supported these results as they pinpoint the importance of the primary OH group in stabilizing the BChE inhibitor complex. A size-exclusion mechanism for inhibition has been proposed based on the fact that acetylcholinesterase (AChE) exhibits several bulky residues that hinder access to the active-site cavity. This work shows how the deoxygenation pattern, configuration and functionality of the anomeric centre can tune physical and surface properties as well as the bioactivity of these multifunctional and stereochemically rich molecules.FEDER e FCTinfo:eu-repo/semantics/publishedVersio

Glucosylpolyphenols as Inhibitors of Aβ-Induced Fyn Kinase Activation and Tau Phosphorylation: Synthesis, Membrane Permeability, and Exploratory Target Assessment within the Scope of Type 2 Diabetes and Alzheimer's Disease

Despite the rapidly increasing number of patients suffering from type 2 diabetes, Alzheimer's disease, and diabetes-induced dementia, there are no disease-modifying therapies that are able to prevent or block disease progress. In this work, we investigate the potential of nature-inspired glucosylpolyphenols against relevant targets, including islet amyloid polypeptide, glucosidases, and cholinesterases. Moreover, with the premise of Fyn kinase as a paradigm-shifting target in Alzheimer's drug discovery, we explore glucosylpolyphenols as blockers of Aβ-induced Fyn kinase activation while looking into downstream effects leading to Tau hyperphosphorylation. Several compounds inhibit Aβ-induced Fyn kinase activation and decrease pTau levels at 10 μM concentration, particularly the per-O-methylated glucosylacetophloroglucinol and the 4-glucosylcatechol dibenzoate, the latter inhibiting also butyrylcholinesterase and β-glucosidase. Both compounds are nontoxic with ideal pharmacokinetic properties for further development. This work ultimately highlights the multitarget nature, fine structural tuning capacity, and valuable therapeutic significance of glucosylpolyphenols in the context of these metabolic and neurodegenerative disorders

Sugar-based bactericides targeting phosphatidylethanolamine-enriched membranes

Free PMC Article: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6242839/Anthrax is an infectious disease caused by Bacillus anthracis, a bioterrorism agent that develops resistance to clinically used antibiotics. Therefore, alternative mechanisms of action remain a challenge. Herein, we disclose deoxy glycosides responsible for specific carbohydrate-phospholipid interactions, causing phosphatidylethanolamine lamellar-to-inverted hexagonal phase transition and acting over B. anthracis and Bacillus cereus as potent and selective bactericides. Biological studies of the synthesized compound series differing in the anomeric atom, glycone configuration and deoxygenation pattern show that the latter is indeed a key modulator of efficacy and selectivity. Biomolecular simulations show no tendency to pore formation, whereas differential metabolomics and genomics rule out proteins as targets. Complete bacteria cell death in 10 min and cellular envelope disruption corroborate an effect over lipid polymorphism. Biophysical approaches show monolayer and bilayer reorganization with fast and high permeabilizing activity toward phosphatidylethanolamine membranes. Absence of bacterial resistance further supports this mechanism, triggering innovation on membrane-targeting antimicrobials.The European Union is gratefully acknowledged for the support of the project “Diagnostic and Drug Discovery Initiative for Alzheimer’s Disease” (D3i4AD), FP7-PEOPLE-2013-IAPP, GA 612347. We thank the Management Authorities of the European Regional Development Fund and the National Strategic Reference Framework for the support of the Incentive System - Research and Technological Development Co-Promotion FACIB Project number 21457. Fundação para a Ciência e a Tecnologia is also acknowledged for the support of projects UID/Multi/00612/2013, FCT/UID/ Multi/04046/2013, IF/00808/2013/CP1159/CT0003, PTDC/BBBBQB/6071/2014, as well as for the post-doc grant SFRH/BPD/42567/2007 (A.M.), the Ph.D. grants SFRH/BDE/51998/2012 (C.D.), and SFRH/BDE/51957/2012 (J.P.P.), both co-sponsored by CIPAN, and also for the Ph.D. grant SFRH/BD/116614/2016 (R.N.).info:eu-repo/semantics/publishedVersio

Coupling Constant pH Molecular Dynamics with Accelerated Molecular Dynamics

An extension of the constant pH method originally implemented by Mongan et al. (J. Comput. Chem.2004, 25, 2038−2048) is proposed in this study. This adapted version of the method couples the constant pH methodology with the enhanced sampling technique of accelerated molecular dynamics, in an attempt to overcome the sampling issues encountered with current standard constant pH molecular dynamics methods. Although good results were reported by Mongan et al. on application of the standard method to the hen egg-white lysozyme (HEWL) system, residues which possess strong interactions with neighboring groups tend to converge slowly, resulting in the reported inconsistencies for predicted pKa values, as highlighted by the authors. The application of the coupled method described in this study to the HEWL system displays improvements over the standard version of the method, with the improved sampling leading to faster convergence and producing pKa values in closer agreement to those obtained experimentally for the more slowly converging residues

“Healthy Life”: interaction of polyphenols with lipid bilayers and their effects in human cells

This work concerns the transversal project of the CQB thematic line: “Healthy Life: Molecular Interventions and Regulation Mechanisms”. Biologically active plant phytochemicals have a broad range of pharmacological effects including anticarcinogenic, antimicrobial, antioxidant, and anti-inflammatory activity. [1] Notwithstanding the possibility of having a specific target, phytochemicals must interact and permeate through cell membranes in the body. Indeed, it was suggested that those molecules insert into the membranes and thereby may have a promiscuous activity by changing structural properties of lipid bilayers. [2] Some well-known phenolic acids such as caffeic (CA), rosmarinic (RA) and chlorogenic (CGA) acids, whose identification in plant extracts has been achieved by CQB research groups, were selected to be addressed in first place. All the phenolic acids studied have low lipophilicity and among them, RA was the only one with a partition to biological membrane models measurable by fluorescence spectroscopy, as opposed to CA and CGA. Cyclic voltammetry measurements using an electrode modified with a supported lipid bilayer, also indicated a higher affinity of RA to lipid membranes. In addition, oxidation/reduction of the phenolic acids displayed higher reversibility in the lipid milieu than in the aqueous bulk. Indeed, the reduced form of phenolic acids was unstable in aqueous solution. In particular, in DMEM/F-12 cell culture media, a colour change observed after incubation with each compound could be reverted by the addition of a reducing agent. The higher reversibility of phenolic acids oxidation/reduction, once they were inserted in the lipid membrane, may contribute to the stability of the compounds and prevent the formation of degradation products. Molecular dynamics (MD) simulations are being performed to probe the location and orientation of these and other selected compounds in lipid bilayers. The influence of the phenolic acids in the cytoskeleton organization, both actin filaments and microtubules, of a human retinal pigment epithelial cell line (RPE1) was also investigated. All compounds induced concentration and time dependent effects, translated in structural alterations mainly at the cell periphery, and also in the perturbation of cell division. Moreover, it was not evident that these compounds induce apoptosis under the conditions tested. RA seemed to induce evident effects at earlier times and at lower concentrations, as compared to CA and CGA. This higher sensibility of RPE1 cells to RA correlates with the higher affinity of this compound to the lipid bilayer.info:eu-repo/semantics/publishedVersio

Inter-domain Communication Mechanisms in an ABC Importer: A Molecular Dynamics Study of the MalFGK2E Complex

ATP-Binding Cassette transporters are ubiquitous membrane proteins that convert the energy from ATP-binding and hydrolysis into conformational changes of the transmembrane region to allow the translocation of substrates against their concentration gradient. Despite the large amount of structural and biochemical data available for this family, it is still not clear how the energy obtained from ATP hydrolysis in the ATPase domains is “transmitted” to the transmembrane domains. In this work, we focus our attention on the consequences of hydrolysis and inorganic phosphate exit in the maltose uptake system (MalFGK2E) from Escherichia coli. The prime goal is to identify and map the structural changes occurring during an ATP-hydrolytic cycle. For that, we use extensive molecular dynamics simulations to study three potential intermediate states (with 10 replicates each): an ATP-bound, an ADP plus inorganic phosphate-bound and an ADP-bound state. Our results show that the residues presenting major rearrangements are located in the A-loop, in the helical sub-domain, and in the “EAA motif” (especially in the “coupling helices” region). Additionally, in one of the simulations with ADP we were able to observe the opening of the NBD dimer accompanied by the dissociation of ADP from the ABC signature motif, but not from its corresponding P-loop motif. This work, together with several other MD studies, suggests a common communication mechanism both for importers and exporters, in which ATP-hydrolysis induces conformational changes in the helical sub-domain region, in turn transferred to the transmembrane domains via the “coupling helices”

Exploring the Structural Properties of Positively Charged peptide Dendrimers

We report a combined experimental and computational approach to study the structural behavior of positively charged peptide dendrimers. Third-generation dendrimers containing combinations of positive/neutral amino acid residues in the different dendrimer generations were synthesized and their overall size evaluated using diffusion NMR. Molecular dynamics simulations were performed to obtain a comprehensive description of the molecular-level phenomena substantiating the structural differences observed. Comparison of the results presented with previous findings reveals a striking charge-dependent tendency in these systems, where the simple number and placement of charged amino acids in the sequence allows an extensive control over the exhibited structural features. Indeed, we observe that peptide dendrimers bearing progressively higher amounts of charged residues are characterized by an increasing structural plasticity, with a myriad of conformational states equally accessible to them. On the other hand, dendrimers containing only small amounts of charged residues evidence, to some extent, a characteristic structural rigidity