Probing Gallate-Mediated Selectivity and High-Affinity Binding of Epigallocatechin Gallate: a Way-Forward in the Design of Selective Inhibitors for Anti-apoptotic Bcl-2 Proteins

Synthesis and characterization of gold(I) thiolate derivatives and bimetallic complexes for HIV inhibition

Introduction: The human immunodeficiency virus (HIV) remains a significant global health concern, with a reported high infection rate of 38.4 million cases globally; an estimated 2 million new infections and approximately 700,000 HIV/AIDS-related deaths were reported in 2021. Despite the advent of anti-retroviral therapy (ART), HIV/AIDS persists as a chronic disease. To combat this, several studies focus on developing inhibitors targeting various stages of the HIV infection cycle, including HIV-1 protease. This study aims to synthesize and characterize novel glyco diphenylphosphino metal complexes with potential HIV inhibitory properties. Method: A series of new gold(I) thiolate derivatives and three bimetallic complexes, incorporating amino phosphines and thiocarbohydrate as auxiliary ligands, were synthesized using procedures described by Jiang, et al. (2009) and Coetzee et al. (2007). Structural elucidation and purity assessment of the synthesized compounds (1-11) were conducted using micro-analysis, NMR, and infrared spectrometry. Results and Discussion: Using molecular modeling techniques, three of the metal complexes were identified as potential HIV protease inhibitors, exhibiting strong binding affinity interactions with binding pocket residues. These inhibitors demonstrated an ability to inhibit the flexibility of the flap regions of the HIV protease, similar to the known HIV protease inhibitor, darunavir. This study sheds light on the promising avenues for the development of novel therapeutic agents against HIV/AIDS.

Antitumor Effect of Epigallocatechin Gallate and Vincristine in Mice with L5178Y Lymphoma

The main objective of research into new therapies is the search for more efficacy and fewer toxic effects in cancer treatments. On one hand, vincristine (VCR) is a chemotherapeutic used in different kinds of tumors. On the other hand, epigallocatechin gallate (EGCG) is a green tea metabolite that has shown an antineoplastic effect in diverse investigations, so the objective of this work is to evaluate the antitumor effects of the EGCG/VCR combination on tumor volume and survival. To achieve this objective, the solid model of lymphoma L5178Y was used in BALB/c mice with different doses of VCR, EGCG, and their combination allowed tumor growth and survival time recording. After tumor collection, measurements, and immunohistochemistry for p53, Bcl2, and Cyclin D1 were performed. The results showed that the EGCG/vincristine combination had a greater antitumor effect than those effects of vincristine and EGCG. It can be attributed to the fact that the greatest inhibition of Bcl2 was present in gathering of EGCG harvest with vincristine. Therefore, the combination of EGCG with vincristine has a better antineoplastic effect by inhibiting tumor development and increasing survival on both substances independently.

An integrated approach for identifying the efficacy and potential mechanisms of TCM against atherosclerosis-Wu-Zhu-Yu decoction as a case study

ETHNOPHARMACOLOGICAL RELEVANCE

Atherosclerosis (AS) is a chronic disease that is associated with high morbidity. However, therapeutic approaches are limited. Wu-Zhu-Yu decoction (WZYD) is a well-known traditional Chinese medicine prescription that is traditionally used to treat headaches and vomiting. Modern studies have demonstrated the cardiotonic effects of WZYD. However, whether WZYD can alleviate AS and its underlying mechanisms remain unclear.

AIM OF THE STUDY

This study aims to investigate the antiatherosclerotic efficacy of WZYD and illustrate its potential mechanisms using an integrated approach combining in vivo and in vitro assessments, including metabolomics, network pharmacology, cell experiments, and molecular docking analyses.

MATERIALS AND METHODS

In this work, an atherosclerotic mouse model was established by administering a high-fat diet to apolipoprotein-E deficient (ApoE^-/-) mice for twelve weeks. Meanwhile, the mice were intragastrically administered WZYD at different dosages. Efficacy evaluation was performed through biochemical and histopathological assessments. The potential active constituents, metabolites, and targets of WZYD in atherosclerosis were predicted by metabolomics combined with network pharmacology analysis, the constituents and targets were further assessed through cell experiments and molecular docking analysis.

RESULTS

WZYD decreased the lipid levels in serum, reduced the areas of aortic lesions, and attenuated intimal thickening, which had antiatherosclerotic effects in ApoE^-/- mice. Metabolomics and network pharmacology approach revealed that the ten constituents (6-shogaol, evodiamine, isorhamnetin, quercetin, beta-carotene, 8-gingerol, kaempferol, 6-paradol, 10-gingerol, and 6-gingerol) of WZYD affected 24 metabolites by acting on the candidate targets, thus resulting in changes in five metabolic pathways (sphingolipid metabolism; glycine, serine and threonine metabolism; arachidonic acid metabolism; tryptophan metabolism; and fatty acid biosynthesis pathway). Cell experiments indicated that the ten key compounds showed antiproliferative effects on the vascular smooth muscle cell. Moreover, the key compounds exhibited direct interactions with the key targets, as assessed by molecular docking analysis.

CONCLUSION

This study revealed that WZYD exerted therapeutic effects on atherosclerosis, and the potential mechanisms were elucidated. Furthermore, it offered a powerful integrated strategy for studying the efficacy of traditional Chinese medicine and exploring its active components and possible mechanisms.

Unravelling the Structural Mechanism of Action of 5-methyl-5-[4-(4-oxo-3H-quinazolin-2-yl)phenyl]imidazolidine-2,4-dione in Dual-Targeting Tankyrase 1 and 2: A Novel Avenue in Cancer Therapy

Tankyrase (TNKS) belonging to the poly(ADPribose) polymerase family, are known for their multi-functioning capabilities, and play an essential role in the Wnt β-catenin pathway and various other cellular processes. Although showing inhibitory potential at a nanomolar level, the structural dual-inhibitory mechanism of the novel TNKS inhibitor, 5-methyl-5-[4-(4-oxo-3H-quinazolin-2-yl)phenyl]imidazolidine-2,4-dione, remains unexplored. By employing advanced molecular modeling, this study provides these insights. Results of sequence alignments of binding site residues identified conserved residues; GLY1185 and ILE1224 in TNKS-1 and PHE1035 and PRO1034 in TNKS-2 as crucial mediators of the dual binding mechanism of 5-methyl-5-[4-(4-oxo-3H-quinazolin-2-yl)phenyl]imidazolidine-2,4-dione, corroborated by high per-residue energy contributions and consistent high-affinity interactions of these residues. Estimation of the binding free energy of 5-methyl-5-[4-(4-oxo-3H-quinazolin-2-yl)phenyl]imidazolidine-2,4-dione showed estimated total energy of -43.88 kcal/mol and -30.79 kcal/mol towards TNKS-1 and 2, respectively, indicating favorable analogous dual binding as previously reported. Assessment of the conformational dynamics of TNKS-1 and 2 upon the binding of 5-methyl-5-[4-(4-oxo-3H-quinazolin-2-yl)phenyl]imidazolidine-2,4-dione revealed similar structural changes characterized by increased flexibility and solvent assessible surface area of the residues inferring an analogous structural binding mechanism. Insights from this study show that peculiar, conserved residues are the driving force behind the dual inhibitory mechanism of 5-methyl-5-[4-(4-oxo-3H-quinazolin-2-yl)phenyl]imidazolidine-2,4-dione and could aid in the design of novel dual inhibitors of TNKS-1 and 2 with improved therapeutic properties.

Natural phyto, compounds as possible noncovalent inhibitors against SARS-CoV2 protease: computational approach

At present, there is no cure or vaccine for the devastating new highly infectious severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that has affected people globally. Herein, we identified potent phytocompounds from two antiviral plants Momordica charantia L. and Azadirachta indica used locally for the treatment of viral and parasitic infections. Structure-based virtual screening and molecular dynamics (MD) simulation have been employed to study their inhibitory potential against the main protease (Mpro) SARS-CoV-2. A total of 86 compounds from M. charantia L. and A. indica were identified. The top six phytocompounds; momordicine, deacetylnimninene, margolonone, momordiciode F2, nimbandiol, 17-hydroxyazadiradione were examined and when compared with three FDA reference drugs (remdesivir, hydroxychloroquine and ribavirin). The top six ranked compounds and FDA drugs were then subjected to MD simulation and pharmacokinetic studies. These phytocompounds showed strong and stable interactions with the active site amino acid residues of SARS-CoV-2 Mpro similar to the reference compound. Results obtained from this study showed that momordicine and momordiciode F2 exhibited good inhibition potential (best MMGBA-binding energies; -41.1 and -43.4 kcal/mol) against the Mpro of SARS-CoV-2 when compared with FDA reference anti-viral drugs (Ribavirin, remdesivir and hydroxychloroquine). Per-residue analysis, root mean square deviation and solvent-accessible surface area revealed that compounds interacted with key amino acid residues at the active site of the enzyme and showed good system stability. The results obtained in this study show that these phytocompounds could emerge as promising therapeutic inhibitors for the Mpro of SARS-CoV-2. However, urgent trials should be conducted to validate this outcome.Communicated by Ramaswamy H. Sarma.

Dual-Inhibition of Human N-Myristoyltransferase Subtypes Halts Common Cold Pathogenesis: Atomistic Perspectives from the Case of IMP-1088

The pharmacological inhibition of human N-myristoyltransferase (HsNMT) has emerged as an efficient strategy to completely prevent the replication process of rhinoviruses, a potential treatment for the common cold. This was corroborated by the recent discovery of compound IMP-1088, a novel inhibitor that demonstrated a dual-inhibitory activity against the two HsNMT subtypes 1 and 2 without inducing cytotoxicity. However, the molecular and structural basis for the dual-inhibitory potential of IMP-1088 has not been investigated. As such, we employ molecular modelling techniques to resolve the structural mechanisms that account for the dual-inhibitory prowess of IMP-1088. Sequence and nanosecond-based analyses identified Tyr296, Phe190, Tyr420, Leu453, Gln496, Val181, Leu474, Glu182, and Asn246 as residues common within the binding pockets of both HsNMT1 and HsNMT2 subtypes whose consistent interactions with IMP-1088 underpin the basis for its dual inhibitory potency. Nano-second-based assessment of interaction dynamics revealed that Tyr296 consistently elicited high-affinity π-π stacked interaction with IMP-1088, thus further highlighting its cruciality corroborating previous report. An exploration of resulting structural changes upon IMP-1088 binding further revealed a characteristic impeding of residue fluctuations, structural compactness, and a consequential burial of crucial hydrophobic residues, features required for HsNMT1/2 functionality. Findings present essential structural perspectives that augment previous experimental efforts and could also advance drug development for treating respiratory tract infections, especially those mediated by rhinoviruses.

Mechanistic Insights into the Selective Dual BET and PLK1 Inhibitory Activity of a Novel Benzamide Compound in Castration-Resistant Prostrate Cancer

Though multifactorial, BET and PLK1 proteins have been found to be key players in the oncogenic process leading to castration-resistant prostate cancer through regulation of AR and MYC-mediated transcription. Hence, dual inhibition of these proteins appears to be an auspicious approach for CRPC therapy. WNY0824 has been reported to exhibit nanomolar range inhibition as well as significant anti-proliferative activity on AR-positive CRPC cells in vitro. However, structural, and mechanistic events associated with its dual inhibitory and anti-proliferative mechanisms remain unclear. Utilizing integrative computer-assisted atomistic techniques, analyses revealed that the dual-inhibitory activity of WNY0824 against BRD4 and PLK1 proteins is mediated by conserved residues present in the binding cavities of both proteins which are shown to elicit various strong intermolecular interactions and thus favour binding affinity. Also, binding orientation of the ligand at the protein binding cavities allowed for important hydrophobic interactions which resulted in high binding free energy of -42.50 kcal/mol and -51.64 kcal/mol towards BRD4 and PLK1, respectively. While van der Waals interactions are very important to ligand binding in BRD4-WNY complex, electrostatic interactions are pertinent to PLK1-WNY complex. Intriguingly, WNY0824 triggered conformational alterations in both proteins through increased structural instability, decreased structural compactness and mitigation in exposure of residues to solvent surface area. Consequently, critical interactions peculiar to the oncogenic activities of BRD4 and PLK1 were inhibited, a phenomenon that results in an antagonism of CRPC progression. The mechanistic insights presented in this report would further assist in the structure-based design of improved inhibitors useful in CRPC therapy.

Immunoinformatics prediction of potential B-cell and T-cell epitopes as effective vaccine candidates for eliciting immunogenic responses against Epstein-Barr virus

BACKGROUND

The ongoing search for viable treatment options to curtail Epstein Barr Virus (EBV) pathogenicity has necessitated a paradigmatic shift towards the design of peptide-based vaccines. Potential B-cell and T-cell epitopes were predicted for nine antigenic EBV proteins that mediate epithelial cell-attachment and spread, capsid self-assembly, DNA replication and processivity.

METHODS

Predictive algorithms incorporated in the Immune Epitope Database (IEDB) resources were used to determine potential B-cell epitopes based on their physicochemical attributes. These were combined with a string-kernel method and an antigenicity predictive AlgPred tool to enhance accuracy in the end-point selection of highly potential antigenic EBV B-cell epitopes. NetCTL 1.2 algorithms enabled the prediction of probable T-cell epitopes which were structurally modeled and subjected to blind peptide-protein docking with HLA-A*02:01. All-atom molecular dynamics (MD) simulation and Molecular Mechanics Generalized-Born Surface Area methods were used to investigate interaction dynamics and affinities of predicted T-cell peptide-protein complexes.

RESULTS

Computational predictions and sequence overlapping analysis yielded 18 linear (continuous) and discontinuous (conformational) subunit epitopes from the antigenic proteins with characteristic surface accessibility, flexibility and antigenicity, and predictive scores above the threshold value (1) set. A novel site was identified on HLA-A*02:01 with preferential affinity binding for modeled BMRF2, BXLF1 and BGLF4 T-cell epitopes. Interaction dynamics and energies were also computed in addition to crucial residues that mediated complex formation and stability.

CONCLUSION

This study implemented an integrative meta-analytical approach to model highly probable B-cell and T-cell epitopes as potential peptide-vaccine candidates for the treatment of EBV-related diseases.

Piece of the puzzle: Remdesivir disassembles the multimeric SARS-CoV-2 RNA-dependent RNA polymerase complex

The recently emerged SARS-like coronavirus (SARS-CoV-2) has continued to spread rapidly among humans with alarming upsurges in global mortality rates. A major key to tackling this virus is to disrupt its RNA replication process as previously reported for Remdesivir (Rem-P₃). In this study, we theorize, using computational simulations, novel mechanisms that may underlie the binding of Rem-P₃ to SARS-CoV-2 RdRp-NSPs complex; a multimeric assembly that drives viral RNA replication in human hosts. Findings revealed that while ATP-binding stabilized the replicative tripartite, Rem-P₃ disintegrated the RdRp-NSP complex, starting with the detachment of the NSP7-NSP8 heterodimer followed by minimal displacement of the second NSP8 subunit (NSP8_II). More so, Rem-P₃ interacted with a relatively higher affinity (ΔG_bind) while inducing high perturbations across the RdRp-NSP domains. D452, T556, V557, S682, and D760 were identified for their crucial roles in stacking the cyano-adenosine and 3,4-dihydroxyoxolan rings of Rem-P₃ while its flexible P₃ tail extended towards the palm domain blocking D618 and K798; a residue-pair identified for essential roles in RNA replication. However, ATP folded away from D618 indicative of a more coordinated binding favorable for nucleotide polymerization. We believe findings from this study will significantly contribute to the structure-based design of novel disruptors of the SARS-CoV-2 RNA replicative machinery.

Identification of potential SARS-CoV-2 inhibitors from South African medicinal plant extracts using molecular modelling approaches

The coronavirus is a group of viruses found in animals as well as humans and have been detected since the 1960s. However, a newly identified form, SARS-CoV-2, has triggered a recent pandemic of respiratory disease now called COVID-19. There is currently no specific antiviral drug for the treatment of this pandemic, with most treatment strategies focused on symptomatic management and supportive therapy. As such, several drug discovery efforts are ongoing for potent treatment agents, with medicinal plants gradually gaining prominence. Approximately 80% of the South African population use traditional medicines to meet their primary health care needs. The current study aimed to identify potential COVID-19 therapeutic agents from a list of 29 bioactive compounds isolated from commonly used South African medicinal plants using molecular docking and molecular dynamics. Molecular docking identified arabic acid from Acacia senegal and L-canavanine found in Sutherlandia frutescens as a potential inhibitor of SARS-CoV-2 3C-like main protease. Similarly, hypoxoside isolated from Hypoxis hemerocallidea and uzarin from Xysmalobium undulatum, were identified as a potential inhibitor of SARS-CoV-2 receptor binding domain and SARS-CoV-2 RNA-dependent polymerase. These four bioactive compounds exhibited favourable binding orientations characterized by strong molecular interactions within respective inhibitors binding pockets of the target enzymes. Molecular dynamics simulations revealed that the binding of the identified inhibitors are characterized by structural perturbations which favour the inhibitory potency of these bioactive compounds. Additionally, in silico pharmacokinetic assessment of the compounds demonstrated favourable anti-SARS-CoV-2 properties. Although not conclusive, further experimental exploration of these compounds could serve as a starting point for the discovery of novel SARS-CoV-2 therapeutic.

'Polymorphism-aided' Selective Targeting and Inhibition of Caspase-6 by a Novel Allosteric Inhibitor Towards Efficient Alzheimer's Disease Treatment

The predominance of Alzheimer's disease (AD) among the aged remains a global challenge. As such, the search for alternative and effective therapeutic options continuous unabated. Among the therapeutic targets explored over the years toward impeding the progression of AD is caspase-6 (Casp6), although selectively targeting Casp6 remains a challenge due to high homology with other members of the caspase family. Methyl 3-[(2,3-dihydro-1-benzofuran-2-yl formamido) methyl]-5-(furan-2-amido) benzoate (C13), a novel allosteric inhibitor, is reportedly shown to exhibit selective inhibition against mutant human Casp6 variants (E35K). However, structural and atomistic insights accounting for the reported inhibitory prowess of C13 remains unresolved. In this study, we seek to unravel the mechanistic selectivity of C13 coupled with the complementary effects of E35K single-nucleotide polymorphism (SNP) relative to Casp6 inhibition. Analyses of binding dynamics revealed that the variant Lysine-35 mediated consistent high-affinity interactions with C13 at the allosteric site, possibly forming the molecular basis of the selectivity of C13 as well as its high binding free energy as estimated. Analysis of residue interaction network around Glu35 and Lys35 revealed prominent residue network distortions in the mutant Casp6 conformation evidenced by a decrease in node degree, reduced number of edges and an increase short in path length relative to a more compact conformation in the wild system. The relatively higher binding free energy of C13 coupled with the stronger intermolecular interactions elicited in the mutant conformation further suggests that the mutation E35K probably favours the inhibitory activity of C13. Further analysis of atomistic changes showed increased C-α atom deviations consistent with structural disorientations in the mutant Casp6. Structural Insights provided could open up a novel paradigm of structure-based design of selective allosteric inhibition of Casp6 towards the treatment of neurodegenerative diseases.

Revealing the role of fluorine pharmacophore in chalcone scaffold for shifting the MAO-B selectivity: investigation of a detailed molecular dynamics and quantum chemical study

The development of highly selective monoamine oxidase-B (MAO-B) inhibitors has great therapeutic benefit in treatment of various neurodegenerative disorders. Recent study documented that shifting of fluorine atom from para to ortho position on the phenyl B ring of heteroaryl chalcones shown a remarkable shift in the selectivity and potency between MAO-A and MAO-B isoforms. Despite the large plethora of the design of new selective MAO-B inhibitors, the current paper illustrates the role and orientation of fluorine atom with remarkable MAO-B selectivity of three compounds (O23, O24 and O25), which differ from all other substituents encountered in the chalcone scaffolds is recently reported by our group. Conformational analyses of differential inhibitory effects of O23, O24 and O25 on MAO-A and MAO-B, differential analyses of complementary interactions at MAO-A/-B active sites and differential analysis of affinity binding and per-residue energy contributions are calculated by molecular dynamics study. Density functional theory based electronic structure calculations were employed with special emphasis to electrostatic potential and frontier molecular orbitals. Results of the current study can be used for lead modification and a new insight for the development of novel fluorinated chalcones for the treatment of various neurodegenerative disorders. Communicated by Ramaswamy H. Sarma.

Tweaking α -Galactoceramides: Probing the Dynamical Mechanisms of Improved Recognition for Invariant Natural Killer T-cell Receptor in Cancer Immunotherapeutics

BACKGROUND

The last few decades have witnessed groundbreaking research geared towards immune surveillance mechanisms and have yielded significant improvements in the field of cancer immunotherapy. This approach narrows down on the development of therapeutic agents that either activate or enhance the recognitive function of the immune system to facilitate the destruction of malignant cells. The α -galactosylceramide derivative, KRN7000, is an immunotherapeutic agent that has gained attention due to its pharmacological ability to activate CD1d-restricted invariant natural killer T(iNKT) cells with notable potency against cancer cells in mouse models; a therapeutic success was not well replicated in human models. Dual structural modification of KRN7000 entailing the incorporation of hydrocinnamoyl ester on C6" and C4-OH truncation of the sphingoid base led to the development of AH10-7 which, interestingly, exhibited high potency in human cells.

OBJECTIVE/METHODS

Therefore, to gain molecular insights into the structural dynamics and selective mechanisms of AH10-7 for human variants, we employed integrative molecular dynamics simulations and thermodynamic calculations to investigate the inhibitory activities of KRN7000 andAH10-7 on hTCR-CD1d towards activating iNKT.

RESULTS

Interestingly, our findings revealed that AH10-7 exhibited higher affinity binding and structural effects on hTCR-CD1d, as mediated by the incorporated hydrocinnamoyl ester moiety which accounted for stronger intermolecular interactions with 'non-common' binding site residues.

CONCLUSION

Findings extracted from this study further reveal important molecular and structural perspectives that could aid in the design of novel α-GalCer derivatives for cancer immunotherapeutics.

Deciphering the 'Elixir of Life': Dynamic Perspectives into the Allosteric Modulation of Mitochondrial ATP Synthase by J147, a Novel Drug in the Treatment of Alzheimer's Disease

The discovery of J147 represented a significant milestone in the treatment of age-related disorders, which was further augmented by the recent identification of mitochondrial ATP synthase as the therapeutic target. However, the underlying molecular events associated with the modulatory activity of J147 have remained unresolved till date. Herein, we present, for the first time, a dynamical approach to investigate the allosteric regulation of mATP synthase by J147, using a reliable human αγβ protein model. The highlight of our findings is the existence of the J147-bound protein in distinct structural associations at different MD simulation periods coupled with concurrent open↔close transitions of the β catalytic and α allosteric (ATP5A) sites as defined by Cα distances (d), TriCα (Θ) and dihedral (φ) angular parameters. Firstly, there was an initial pairing of the αγ subunits away from the β subunit followed by the formation of the 'non-catalytic' αβ pair at a distance from the γ subunit. Interestingly, J147-induced structural arrangements were accompanied by the systematic transition of the β catalytic site from a closed to an open state, while there was a concurrent transition of the allosteric site from an open α_E conformation to a closed state. Consequentially, J147 reduced the structural activity of the whole αγβ complex, while the unbound system exhibited high atomistic deviations and structural flexibility. Furthermore, J147 exhibited favorable binding at the allosteric site of mATP synthase with considerable electrostatic energy contributions from Gln215, Gly217, Thr219, Asp312, Asp313, Glu371 and Arg406. These findings provide details on the possible effects of J147 on mitochondrial bioenergetics, which could facilitate the structure-based design of novel small-molecule modulators of mATP synthase in the management of Alzheimer's disease and other neurodegenerative disorders.

Turning to Computer-aided Drug Design in the Treatment of Diffuse Large B-cell Lymphoma: Has it been Helpful?

INTRODUCTION

Amidst the numerous effective therapeutic options available for the treatment of Diffuse Large B-cell Lymphoma (DLBCL), about 30-40% of patients treated with first-line chemoimmunotherapy still experience a relapse or refractory DLBCL. This has necessitated a continuous search for new therapeutic agents to augment the existing therapeutic arsenal.

METHODS

The dawn of Computer-Aided Drug Design (CADD) in the drug discovery process has accounted for persistency in the application of computational approaches either alone or in combinatorial strategies with experimental methods towards the identification of potential hit compounds with high therapeutic efficacy in abrogating DLBCL.

RESULTS

This review showcases the interventions of structure-based and ligand-based computational approaches which have led to the identification of numerous small molecule inhibitors against implicated targets in DLBCL therapy, even though many of these potential inhibitors are piled-up awaiting further experimental validation and exploration.

CONCLUSION

We conclude that a successful and a conscious amalgamation of CADD and experimental approaches could pave the way for the discovery of the next generation potential leads in DLBCL therapy with improved activities and minimal toxicities.

Molecular Targets of Epigallocatechin-Gallate (EGCG): A Special Focus on Signal Transduction and Cancer

Green tea is a beverage that is widely consumed worldwide and is believed to exert effects on different diseases, including cancer. The major components of green tea are catechins, a family of polyphenols. Among them, epigallocatechin-gallate (EGCG) is the most abundant and biologically active. EGCG is widely studied for its anti-cancer properties. However, the cellular and molecular mechanisms explaining its action have not been completely understood, yet. EGCG is effective in vivo at micromolar concentrations, suggesting that its action is mediated by interaction with specific targets that are involved in the regulation of crucial steps of cell proliferation, survival, and metastatic spread. Recently, several proteins have been identified as EGCG direct interactors. Among them, the trans-membrane receptor 67LR has been identified as a high affinity EGCG receptor. 67LR is a master regulator of many pathways affecting cell proliferation or apoptosis, also regulating cancer stem cells (CSCs) activity. EGCG was also found to be interacting directly with Pin1, TGFR-II, and metalloproteinases (MMPs) (mainly MMP2 and MMP9), which respectively regulate EGCG-dependent inhibition of NF-kB, epithelial-mesenchimal transaction (EMT) and cellular invasion. EGCG interacts with DNA methyltransferases (DNMTs) and histone deacetylases (HDACs), which modulates epigenetic changes. The bulk of this novel knowledge provides information about the mechanisms of action of EGCG and may explain its onco-suppressive function. The identification of crucial signalling pathways that are related to cancer onset and progression whose master regulators interacts with EGCG may disclose intriguing pharmacological targets, and eventually lead to novel combined treatments in which EGCG acts synergistically with known drugs.

Does Size Really Matter? Probing the Efficacy of Structural Reduction in the Optimization of Bioderived Compounds - A Computational "Proof-of-Concept"

Over the years, numerous synthetic approaches have been utilized in drug design to improve the pharmacological properties of naturally derived compounds and most importantly, minimize toxic effects associated with their transition to drugs. The reduction of complex bioderived compounds to simpler bioactive fragments has been identified as a viable strategy to develop lead compounds with improved activities and minimal toxicities. Although this ‘reductive’ strategy has been widely exemplified, underlying biological events remain unresolved, hence the unanswered question remains how does the fragmentation of a natural compound improve its bioactivity and reduce toxicities? Herein, using a combinatorial approach, we initialize a computational “proof-of- concept” to expound the differential pharmacological and antagonistic activities of a natural compound, Anguinomycin D, and its synthetic fragment, SB640 towards Exportin Chromosome Region Maintenance 1 (CRM1). Interestingly, our findings revealed that in comparison with the parent compound, SB640 exhibited improved pharmacological attributes, while toxicities and off-target activities were relatively minimal. Moreover, we observed that the reduced size of SB640 allowed ‘deep access’ at the Nuclear Export Signals (NES) binding groove of CRM1, which favored optimal and proximal positioning towards crucial residues while the presence of the long polyketide tail in Anguinomycin D constrained its burial at the hydrophobic groove. Furthermore, with regards to their antagonistic functions, structural inactivation (rigidity) was more pronounced in CRM1 when bound by SB640 as compared to Anguinomycin D. These findings provide essential insights that portray synthetic fragmentation of natural compounds as a feasible approach towards the discovery of potential leads in disease treatment.