Across the blood-brain barrier: Neurotherapeutic screening and characterization of naringenin as a novel CRMP-2 inhibitor in the treatment of Alzheimer's disease using bioinformatics and computational tools

Evaluation of terpenes rich Hura crepitans extract on glucose regulation and diabetic complications in STZ-induced diabetic rats

The continual increase in global diabetic statistics portends decreased productivity and life spans, thus making it a disease of concern requiring more effective and safe therapeutic options. While several reports on antidiabetic plants, including Hura crepitans, are available, there is still a dearth of information on the holistic antidiabetic properties of H. crepitans and its associated complications. This study evaluated the antidiabetic potential of methanolic extract of Hura crepitans using in vitro, in vivo, and in silico approaches. The extract revealed a dose-dependent in vitro effect, with a 47.97 % and 65.34 % decrease in the fasting blood sugar levels of streptozotocin (STZ) induced diabetic rats at 150 and 300 mg/kg BW, respectively. Likewise, the extract increased serum and pancreatic insulin levels, and significantly ameliorated neuronal oxidative stress and inflammation by reducing the expression levels of cholinesterase, NF-κB, and COX-2 in the brain of hyperglycemic rats. Serum dyslipidemia, liver, and kidney biomarker indices, and hematological alterations in diabetic rats were also significantly attenuated by the extract. Several constituents, mainly terpenes, were identified in the extract. To further predict the drug-likeness, pharmacokinetics, and binding properties of the compounds, in silico analysis was conducted. Ergosta-2,24-dien-26-oicacid,18-(acetyloxy)-5,6-epoxy-4, 22-dihydroxy-1-oxo-,delta.-lactone-4.beta., displayed the highest docking scores for acetylcholinesterase, butyrylcholinesterases, alpha-amylase, and nuclear factor-kB with values of -12.4, -10.9, -10.3, and -9.4 kcal/mol, while ergost-25-ene-6,12-dione,3,5-dihydroxy-, (3.beta.,5.alpha.) topped for cyclooxygenase-2 (-9.0 kcal/mol). The top-ranked compounds also presented significant oral drug-likeness, pharmacokinetics, and safety properties. Altogether, our data provide preclinical evidence of the potential of Hura crepitans in ameliorating diabetes and its associated complications.

MAO inhibiting phytochemicals from the roots of Glycyrrhiza glabra L

Glycyrrhizin, a natural compound that is substantially present in Glycyrrhiza glabra L. (Gg) root. Monoamine oxidase B (MAOB) inhibitor is used for the treatment of several important neuropsychological diseases like Parkinson's disease. Gg is known to possess psychoactive properties which relates to its MAO inhibitory potential. This study sought to determine the MAO inhibition property of glycyrrhizin from Gg root extract. The Aqueous extract containing glycyrrhizin was isolated from the root of Gg and characterized using TLC, HPLC, and LC-MS techniques. In silico docking was conducted using Extra precision Glide 2018, Schrödinger docking suite. In addition, the pharmacokinetic properties of the compounds were predicted using SwissADME. The binding energies of the glycyrrhizin correlated well with their in vitro MAO inhibitory potential. Glycyrrhizin exhibited potent inhibitory activity towards MAOB whereas, an aqueous extract of Gg root inhibits both A and B forms of MAO enzyme. Further, molecular docking and molecular dynamics simulation showed that liquiritigenin and methoxyglabridin showed higher stability than other inhibitor compounds from the Gg root extract. These observations suggest that the phytochemicals from the Gg root extract have potent MAO inhibition properties, which can be exploited for the treatment of neurodegenerative disorders.Communicated by Ramaswamy H. Sarma.

Paradigms and Success Stories of Natural Products in Drug Discovery Against Neurodegenerative Disorders (NDDs)

Neurodegenerative disorders (NDDs) are multifaceted complex disorders that have put a great health and economic burden around the globe nowadays. The multi-factorial nature of NDDs has presented a great challenge in drug discovery and continuous efforts are in progress in search of suitable therapeutic candidates. Nature has a great wealth of active principles in its lap that has cured the human population since ancient times. Natural products have revealed several benefits over conventional synthetic medications and scientists have shifted their vision towards exploring the therapeutic potentials of natural products in the past few years. The structural mimicking of natural compounds to endogenous ligands has presented them as a potential therapeutic candidate to prevent the development of NDDs. In the presented review, authors have summarized demographical facts about various NDDs including Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD) and various types of sclerosis in the brain. The significant findings of new active principles of natural origin along with their therapeutic potentials on NDDs have been included. Also, a description of clinical trials and patents on natural products has been enlisted in this compilation. Although natural products have shown promising success in drug discovery against NDDs, still their use is associated with several ethical issues which need to be solved in the upcoming time.

Serotonin Receptors as a Potential Target in the Treatment of Alzheimer's Disease

Alzheimer's disease (AD) is the most common cause of dementia worldwide that has an increasing impact on aging societies. Besides its critical role in the control of various physiological functions and behavior, brain serotonin (5-HT) system is involved in the regulation of migration, proliferation, differentiation, maturation, and programmed death of neurons. At the same time, a growing body of evidence indicates the involvement of 5-HT neurotransmission in the formation of insoluble aggregates of β-amyloid and tau protein, the main histopathological signs of AD. The review describes the role of various 5-HT receptors and intracellular signaling cascades induced by them in the pathological processes leading to the development of AD, first of all, in protein aggregation. Changes in the functioning of certain types of 5-HT receptors or associated intracellular signaling mediators prevent accumulation of β-amyloid plaques and tau protein neurofibrillary tangles. Based on the experimental data, it can be suggested that the use of 5-HT receptors as new drug targets will not only improve cognitive performance in AD, but will be also important in treating the causes of AD-related dementia.

Leveraging Computational Intelligence Techniques for Diagnosing Degenerative Nerve Diseases: A Comprehensive Review, Open Challenges, and Future Research Directions

Degenerative nerve diseases such as Alzheimer's and Parkinson's diseases have always been a global issue of concern. Approximately 1/6th of the world's population suffers from these disorders, yet there are no definitive solutions to cure these diseases after the symptoms set in. The best way to treat these disorders is to detect them at an earlier stage. Many of these diseases are genetic; this enables machine learning algorithms to give inferences based on the patient's medical records and history. Machine learning algorithms such as deep neural networks are also critical for the early identification of degenerative nerve diseases. The significant applications of machine learning and deep learning in early diagnosis and establishing potential therapies for degenerative nerve diseases have motivated us to work on this review paper. Through this review, we covered various machine learning and deep learning algorithms and their application in the diagnosis of degenerative nerve diseases, such as Alzheimer's disease and Parkinson's disease. Furthermore, we also included the recent advancements in each of these models, which improved their capabilities for classifying degenerative nerve diseases. The limitations of each of these methods are also discussed. In the conclusion, we mention open research challenges and various alternative technologies, such as virtual reality and Big data analytics, which can be useful for the diagnosis of degenerative nerve diseases.

A Recent Update on Pathophysiology and Therapeutic Interventions of Alzheimer's Disease

AIM

Alzheimer's disease (AD) has been identified as a progressive brain disorder associated with memory dysfunction and the accumulation of β-amyloid plaques and neurofibrillary tangles of τ protein. Mitochondria is crucial in maintaining cell survival, cell death, calcium regulation, and ATP synthesis. Mitochondrial dysfunction and linked calcium overload have been involved in the pathogenesis of AD. CRM2 (Collapsin response mediator protein-2) is involved in endosomal lysosomal trafficking as well as autophagy, and their reduced level is also a primary culprit in the progression of AD. In addition, Cholinergic neurotransmission and neuroinflammation are two other mechanisms implicated in AD onset and might be protective targets to attenuate disease progression. The microbiota-gut-brain axis (MGBA) is another crucial target for AD treatment. Crosstalk between gut microbiota and brain mutually benefitted each other, dysbiosis in gut microbiota affects the brain functions and leads to AD progression with increased AD-causing biomarkers. Despite the complexity of AD, treatment is only limited to symptomatic management. Therefore, there is an urgent demand for novel therapeutics that target associated pathways responsible for AD pathology. This review explores the role of different mechanisms involved in AD and possible therapeutic targets to protect against disease progression.

BACKGROUND

Amidst various age-related diseases, AD is the most deleterious neurodegenerative disorder that affects more than 24 million people globally. Every year, approximately 7.7 million new cases of dementia have been reported. However, to date, no novel disease-modifying therapies are available to treat AD.

OBJECTIVE

The aim of writing this review is to highlight the role of key biomarker proteins and possible therapeutic interventions that could play a crucial role in mitigating the ongoing prognosis of Alzheimer's disease.

MATERIALS AND METHODS

The available information about the disease was collected through multiple search engines, including PubMed, Science Direct, Clinical Trials, and Google Scholar.

RESULTS

Accumulated pieces of evidence reveal that extracellular aggregation of β-amyloid plaques and intracellular tangles of τ protein are peculiar features of perpetuated Alzheimer's disease (AD). Further, the significant role of mitochondria, calcium, and cholinergic pathways in the pathogenesis of AD makes the respiratory cell organelle a crucial therapeutic target in this neurodegenerative disease. All currently available drugs either delay the clinical damage to cells or temporarily attenuate some symptoms of Alzheimer's disease.

CONCLUSION

The pathological features of AD are extracellular deposition of β-amyloid, acetylcholinesterase deregulation, and intracellular tangles of τ protein. The multifactorial heterogeneity of disease demands more research work in this field to find new therapeutic biological targets.

VANL-100 Attenuates Beta-Amyloid-Induced Toxicity in SH-SY5Y Cells

Antioxidants are being explored as novel therapeutics for the treatment of neurodegenerative diseases such as Alzheimer's disease (AD) through strategies such as chemically linking antioxidants to synthesize novel co-drugs. The main objective of this study was to assess the cytoprotective effects of the novel antioxidant compound VANL-100 in a cellular model of beta-amyloid (Aβ)-induced toxicity. The cytotoxic effects of Aβ in the presence and absence of all antioxidant compounds were measured using the 3-(4,5-dimethylthiazol-2-yl)2-5-diphenyl-2H-tetrazolium bromide (MTT) assay in SH-SY5Y cells in both pre-treatment and co-treatment experiments. In pre-treatment experiments, VANL-100, or one of its parent compounds, naringenin (NAR), alpha-lipoic acid (ALA), or naringenin + alpha-lipoic acid (NAR + ALA), was administrated 24 h prior to an additional 24-h incubation with 20 μM non-fibril or fibril Aβ_25-35. Co-treatment experiments consisted of simultaneous treatment with Aβ and antioxidants. Pre-treatment and co-treatment with VANL-100 significantly attenuated Aβ-induced cell death. There were no significant differences between the protective effects of VANL-100, NAR, ALA, and NAR + ALA with either form of Aβ, or in the effect of VANL-100 between 24-h pre-treatment and co-treatment. These results demonstrate that the novel co-drug VANL-100 is capable of eliciting cytoprotective effects against Aβ-induced toxicity.

Nanodelivery of antiretroviral drugs to nervous tissues

Despite the development of effective combined antiretroviral therapy (cART), the neurocognitive impairments associated with human immunodeficiency virus (HIV) remain challenging. The presence of the blood-brain barrier (BBB) and blood-cerebrospinal fluid barrier (BCFB) impedes the adequate penetration of certain antiretroviral drugs into the brain. In addition, reports have shown that some antiretroviral drugs cause neurotoxicity resulting from their interaction with nervous tissues due to long-term systemic exposure. Therefore, the research into the effective therapeutic modality that would cater for the HIV-associated neurocognitive disorders (HAND) and ART toxicity is now receiving broad research attention. Thus, this review explores the latest information in managing HAND using a nanoparticle drug delivery system (NDDS). We discussed the neurotoxicity profile of various approved ART. Also, we explained the applications of silver nanoparticles (AgNPs) in medicine, their different synthesis methods and their interaction with nervous tissues. Lastly, while proposing AgNPs as useful nanoparticles in properly delivering ART to enhance effectiveness and minimize neurocognitive disorders, we hypothesize that the perceived toxicity of AgNPs could be minimized by taking appropriate precautions. One such precaution is using appropriate reducing and stabilizing agents such as trisodium citrate to reduce silver ion Ag + to ground state Ag0 during the synthesis. Also, the usage of medium-sized, spherical-shaped AgNPs is encouraged in AgNPs-based drug delivery to the brain due to their ability to deliver therapeutic agents across BBB. In addition, characterization and functionalization of the synthesized AgNPs are required during the drug delivery approach. Putting all these factors in place would minimize toxicity and enhance the usage of AgNPs in delivering therapeutic agents across the BBB to the targeted brain tissue and could cater for the HIV-associated neurocognitive disorders and neurotoxic effects of antiretroviral drugs (ARDs).

Angiotensin converting enzyme inhibitors from medicinal plants: a molecular docking and dynamic simulation approach

Angiotensin converting enzyme (ACE) is a key enzyme and mediator in the aetiology of high blood pressure (HBP) and hypertension. As one of the leading cause of untimely death worldwide, there is a lot of research and studies on the management and treatment of hypertension. The usage of medicinal plants in the management of hypertension as alternative to synthetic allopathic drugs is a common practice in folkloric and traditional medicine. Therefore, this study was aimed to investigate the ACE inhibitory activity of some medicinal plants which are commonly used in the treatment of HBP in southwestern part of Nigeria using extensive in-silico approach. Compounds identified in the plants through GC-MS technique, together with Lisinopril were docked against ACE protein. It was observed that only 40 of the compounds had binding affinity ≥ - 6.8 kcal/mol which was demonstrated by the standard drug (lisinopril). Interaction between the compounds and ACE was via conventional hydrogen, carbon hydrogen, alkyl, pi-alkyl, pi-carbon, and Van Der Wall bonds among others. Most of these compounds exhibited drug like properties, without violating majority of the physicochemical descriptors and Lipinski rule of 5. The ADMET evaluation revealed that only 2 compounds (cyclopentadecanone and oxacycloheptadecan-2-one) which were identified in Bacopa florinbunda plant were predicted non-toxic and thus were subjected to molecular dynamics and simulation with ACE. From the molecular dynamics and mechanics analysis, both cyclopentadecanone and oxacycloheptadecan-2-one showed high stability and inhibitory potentials when bound to ACE. Oxacycloheptadecan-2-one was more stable than lisinopril and cyclopentadecanone in the ligand-ACE complex; we therefore suggested its experimental and clinical validation as drug candidates for the treatment of hypertension.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40203-022-00135-z.

Neuroprotective Drug Discovery From Phytochemicals and Metabolites for CNS Viral Infection: A Systems Biology Approach With Clinical and Imaging Validation

Background

Recent studies have reported that pulmo-neurotropic viruses can cause systemic invasion leading to acute respiratory failure and neuroinfection. The tetracycline class of secondary metabolites of microorganisms is effective against several migrating neurotropic viral disorders, as Japanese-Encephalitis (JE), Severe-Acute-Respiratory-Syndrome Coronavirus-2 (SARS-COV2), Human-Immunodeficiency-Virus (HIV), and Simian-Immunodeficiency-Virus (SIV). Another microbial secondary metabolite, cephalosporin, can be used for anti-viral combination therapy. However, a substantial public health debacle is viral resistance to such antibiotics, and, thus, one needs to explore the antiviral efficiency of other secondary metabolites, as phytochemicals. Hence, here, we investigate phytochemicals like podophyllotoxin, chlorogenic acid, naringenin, and quercetin for therapeutic efficiency in neurotropic viral infections.

Methods

To investigate the possibility of the afferent neural pathway of migrating virus in man, MRI scanning was performed on human subjects, whereby the connections between cranial nerves and the brain-stem/limbic-region were assessed by fiber-tractography. Moreover, human clinical-trial assessment (n = 140, p = 0.028) was done for formulating a quantitative model of antiviral pharmacological intervention. Furthermore, docking studies were performed to identify the binding affinity of phytochemicals toward antiviral targets as (i) host receptor [Angiotensin-converting Enzyme-2], (ii) main protease of SARS-COV2 virus (iii) NS3-Helicase/Nucleoside triphosphatase of Japanese-encephalitis-virus, and the affinities were compared to standard tetracycline and cephalosporin antibiotics. Then, network pharmacology analysis was utilized to identify the possible mechanism of action of those phytochemicals.

Results

Human MRI-tractography analysis showed fiber connectivity, as: (a) Path-1: From the olfactory nerve to the limbic region (2) Path-2: From the peripheral glossopharyngeal nerve and vagus nerves to the midbrain-respiratory-center. Docking studies revealed comparable binding affinity of phytochemicals, tetracycline, and cephalosporin antibiotics toward both (a) virus receptors, (b) host cell receptors where virus-receptor binds. The phytochemicals effectively countered the cytokine storm-induced neuroinflammation, a critical pathogenic pathway. We also found that a systems-biology-based double-hit mathematical bi-exponential model accounts for patient survival-curve under antiviral treatment, thus furnishing a quantitative-clinical framework of secondary metabolite action on virus and host cells.

Conclusion

Due to the current viral resistance to antibiotics, we identified novel phytochemicals that can have clinical therapeutic application to neurotropic virus infection. Based on human MRI scanning and clinical-trial analysis, we demarcated the anatomical pathway and systems-biology-based quantitative formulation of the mechanism of antiviral action.

Neuronal CRMP2 phosphorylation inhibition by the flavonoid, naringenin, contributes to the reversal of spinal sensitization and arthritic pain improvement

BACKGROUND

Rheumatoid arthritis patients usually suffer from arthritic chronic pain. However, due to an incomplete understanding of the mechanisms underlying autoimmune disorders, the management of arthritic pain is unsatisfactory. Here, we investigated the analgesic effect and underlying mechanism of the natural flavonoid naringenin (NAR) in collagen-induced arthritis (CIA) pain.

METHODS

NAR was injected (i.p.) once per day for 42 days after initial immunization, and rats were sacrificed on the 28th (the 21st day after final immunization, PID 21) and 42nd days (PID 35). The inflammatory factors, central sensitization indicators, and CRMP2 phosphorylation, as well as the anti-rheumatoid activity and analgesic effect of NAR, were further investigated.

RESULTS

We found that NAR decreased the arthritis score and paw swelling, as well as the mechanical and thermal pain. The immunofluorescence results also showed a dose dependent effect of NAR on reducing the expressions of spinal cFos, IBA-1, and GFAP on the 28th (PID 21) and 42nd day (PID 35). NAR decreased the phosphorylation of CRMP2 S522 and the expression of the kinase CDK5 in the spinal dorsal horn, but pCRMP2 Y479 was unchanged. In addition, CRMP2 was co-localized with NEUN, but not IBA-1 or GFAP, indicating the involvement of neural CRMP2 phosphorylation in CIA-related pain. Finally, CRMP2 S522 phosphorylation selective inhibitor (S)-lacosamide also alleviated arthritic pain.

CONCLUSIONS

Taken together, our results demonstrate that NAR alleviates inflammation and chronic pain in CIA model, which might be related to its inhibition of neuronal CRMP2 S522 phosphorylation, potentially mitigating the central sensitization. Our study provide evidence for the potential use of NAR as non-opioid-dependent analgesia in arthritic pain.

Atomistic insights into the selective therapeutic activity of 6-(2,4-difluorophenoxy)-5-((ethylmethyl)pyridine-3-yl)-8-methylpyrrolo[1,2-a]pyrazin-1(2H)-one towards bromodomain-containing proteins

Cross-target effect has been one of the major mechanisms of drug toxicity, this has necessitated the design of inhibitors that are specifically tailored to target particular biomolecules. 6-(2,4-difluorophenoxy)-5-((ethylmethyl)pyridine-3-yl)-8-methylpyrrolo[1,2-a] pyrazin-1(2H)-one (Cpd38) is an inhibitor possessing high inhibition rate and tailored specificity towards bromodomain-containing protein 4 (BRD4). In this research, we used an array of computational techniques to provide insight at the atomistic level the specific targeting of BRD4 by Cpd38 relative to the binding of Cpd38 with E1A binding protein P300 (EP300); another bromodomain-containing protein (BCP). Comparatively, binding of Cpd38 improved the conformational stability and compactness of BRD4 protein when compared to the Cpd38 bound EP300. Also, Cpd38 induced a conformational change in the active site of BRD4 that facilitated a complementary pose between Cpd38 and BRD4 suitable for effective atomistic interactions. Expectedly, thermodynamic calculations revealed that the Cpd38-BRD4 system had higher binding energy (-36.11 Kcal/mol) than the Cpd38-EP300 system with a free binding energy of -15.86 Kcal/mol. Noteworthy is the opposing role Trp81 (acting as hydrogen bond acceptor) and Pro1074 (acting as hydrogen bond donor) found on the WPF and LPF loops respectively play in maintaining Cpd38 stability. Furthermore, the hydrogen bond acceptor/donator ratio was approximately 4:1 in Cpd38-BRD4 system compared with 2:1 in Cpd38-EP300 system. Taken together, atomistic insights and structural perspectives detailed in this report supplements the experimental report supporting the improved selectivity of Cpd38 for BRD4 ahead of other BCPs while providing leeway for the future design of BET selective agents with better pharmacological profile.

Prospecting the therapeutic edge of a novel compound (B12) over berberine in the selective targeting of Retinoid X Receptor in colon cancer

The Retinoid X Receptor (RXR) is an attractive target in the treatment of colon cancer. Different therapeutic binders with high potency have been used to specifically target RXR. Among these compounds is a novel analogue of berberine, B12. We provided structural and molecular insights into the therapeutic activity properties of B12 relative to its parent compound, berberine, using force field estimations and thermodynamic calculations. Upon binding of B12 to RXR, the high instability elicited by RXR was markedly reduced; similar observation was seen in the berberine-bound RXR. However, our analysis revealed that B12 could have a more stabilizing effect on RXR when compared to berberine. Interestingly, the mechanistic behaviour of B12 in the active site of RXR opposed its impact on RXR protein. This disparity could be due to the bond formation and breaking elicited between B12/berberine and the active site residues. We observed that B12 and berberine could induce a disparate conformational change in regions Gly250-Asp258 located on the His-RXRα/LBD domain. Comparatively, the high agonistic and activation potential reported for B12 compared to berberine might be due to its superior binding affinity as evidenced in the thermodynamic estimations. The total affinity for B12 (-25.76 kcal/mol) was contributed by electrostatic interactions from Glu243 and Glu239. Also, Arg371, which plays a crucial role in the activity of RXR, formed a strong hydrogen bond with B12; however, a weak interaction was elicited between Arg371 and berberine. Taken together, our study has shown the RXRα activating potential of B12, and findings from this study could provide a framework in the future design of RXRα binders specifically tailored in the selective treatment of colon cancer.

Insight into the Therapeutic Potential of a Bicyclic Hydroxypyridone Compound 2-[(2,4-Dichlorophenyl)methyl]-7-hydroxy-1,2,3,4-tetrahydro-8H-pyrido[1,2-a]pyrazin-8-one as COMT Inhibitor in the Treatment of Parkinson's Disease: A Molecular Dynamic Simulation Approach

Parkinson's disease (PD) is one of the most targeted neurodegenerative diseases in clinical research. Awareness of research is due to its increasing number of affected people worldwide. The pathology of PD has been linked to several key proteins upregulation such as the catechol O-Methyltransferase (COMT). Hence, the synthesis of compounds possessing inhibitory capacity has been the frontline of research in recent years. Several compounds have been synthesized among which is the nitrocatechol. However, major limitations associated with the nitrocatechol scaffold include the inability to possess adequate CNS penetration properties and hepatic toxicity associated with the compounds. However, a series of bicyclic hydroxypyridones compounds were synthesized to evaluate their inhibitory potentials on COMT protein with compound 38 (c38) 2-[(2,4-dichlorophenyl)methyl]-7-hydroxy-1,2,3,4-tetrahydro-8H-pyrido[1,2-a]pyrazin-8-one shown to have a 40 fold increase level coverage in its IC₅₀ over brain exposure when compared to the other synthesized compound. The molecular dynamics method was employed to understand the nature of interaction exhibited by c38. Molecular mechanics of c38 revealed a disruptive effect on the secondary structure of COMT protein. Per residue decomposition analysis revealed similar crucial residues involved in the favorable binding of c38 and tolcapone implicated its increased inhibitory capacity on COMT in preventing PD. Free binding energy (ΔG_bind ) of c38 further revealed the inhibitory capacity towards COMT protein in comparison to the FDA approved tolcapone. Ligand mobility analysis of both compounds showed a timewise different mobility pattern across the simulation time frame at the active site pocket of the protein connoting the different inhibitory potency exhibited by c38 and tolcapone. Findings from this study revealed optimization of c38 could facilitate the discovery of new compounds with enhanced inhibitory properties towards COMT in treating PD.

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.

Exploring the Role of Asp1116 in Selective Drug Targeting of CREBcAMP- Responsive Element-binding Protein Implicated in Prostate Cancer

BACKGROUND

The selective targeting of CREB-cAMP-responsive element-binding protein (CBP) has recently evolved as a vital therapeutic approach for curtailing its aberrant upregulation associated with the development of prostate cancer. Inhibition of CBP has been discovered to be an important therapeutic option in androgen receptor signalling pathway mediated prostate cancer. Y08197, a novel selective inhibitor of CBP, has shown promising therapeutic outcome in prostate carcinogenesis over non-selective analogues such as CPI-637.

METHODS/RESULTS

Herein, we used molecular dynamics simulation to gain insights into the mechanistic and selective targeting of Y08197 at the bromodomain active site. Molecular Mechanics/ Poisson-Boltzmann Surface Area (MM/PBSA) analysis revealed a similar inhibitory effect between Y08197 and CPI-637. Furthermore, in exploring the selective affinity of Y08197 towards CBP in combination with Bromodomain and PHD finger-containing protein 1(BRPF1), our findings highlighted Asp1116 as the 'culprit' residue responsible for this selective targeting. Upon binding, Asp1116 assumed a conformation that altered the architecture of the bromodomain active site, thereby orienting the helices around the active site in a more compacted position. In addition to some specific structural perturbations mediated by Asp1116 on the dynamics of CBP, our study revealed that the strong hydrogen bond interaction (N-H...O) elicited in CBP-Y08197 sequestered Y08197 tightly into the CBP bromodomain active site.

CONCLUSION

Conclusively, the inhibition and selective pattern of Y08197 can be replicated in future structure-based CBP inhibitors and other bromodomain implicated in carcinogenesis.

Natural products as pharmacological modulators of mitochondrial dysfunctions for the treatments of Alzheimer's disease: A comprehensive review

Alzheimer's disease (AD) is the most common progressive neurodegenerative disorder characterized by neuronal loss and cognitive impairment that harshly affect the elderly individuals. Currently, the available anti-AD pharmacological approaches are purely symptomatic to alleviate AD symptoms, and the curative effects of novel anti-AD drugs focused on Aβ target are disappointing. Hence, there is a tremendous need to adjust AD therapeutic targets and discover novel anti-AD agents. In AD, mitochondrial dysfunction gradually triggers neuronal death from different aspects and worsens the occurrence and progress of AD. Consequently, it has been proposed that the intervention of impaired mitochondria represents an attractive breakthrough point for AD treatments. Due to chemical diversity, poly-pharmacological activities, few adverse effects and multiple targeting, natural products (NPs) have been identified as a valuable treasure for drug discovery and development. Multiple lines of studies have scientifically proven that NPs display ameliorative benefits in AD treatment in relation to mitochondrial dysfunction. This review surveys the complicated implications for mitochondrial dysregulation and AD, and then summarizes the potentials of NPs and their underlying molecular mechanisms against AD via reducing or improving mitochondrial dysfunction. It is expected that this work may open the window to speed up the development of innovative anti-AD drugs originated from NPs and improve upcoming AD therapeutics.

Piecing the fragments together: Dynamical insights into the enhancement of BRD4-BD1 (BET protein) druggability in cancer chemotherapy using novel 8-methyl-pyrrolo[1,2-a]pyrazin-1(2H)-one derivatives

BACKGROUND

Fragment-based drug discovery in recent times has been explored in the design of highly potent therapeutics.

METHODS

In this study, we explored the inhibitory dynamics of Compound 38 (Cpd38), a newly synthesized Bromodomain-containing protein 4 bromodomain 1 (BRD4-BD1) protein inhibitor derived from the synthetic coupling of Fragment 47 (Fgt47) into ABBV-075 scaffold. Using dynamic simulation methods, we unraveled the augmentative effects of chemical fragmentation on improved BRD4-BD1 inhibition.

RESULTS

Findings from this study revealed that although Fgt47 exhibited a considerable ΔGbind, its incorporation into the difluoro-phenoxy pyridine scaffold (Cpd38) notably enhanced the binding affinity. Time-based analyses of interaction dynamics further revealed that the bulkiness of Cpd38 favored its interaction at the BRD4-BD1 active site relative to the fragment. Strikingly, when compared to Fgt47, Cpd38 demonstrated high mobility, which could have enabled it to bind optimally and complementarily with key residues of the active site such as Ile146, Asn140, Cys136, Tyr98, Leu94, Val87, Phe83 and Trp81.

DISCUSSION

On the contrary, majority of these interactions were gradually lost in Fgt47 which could further indicate the essence of coupling it with the difluoro-phenoxy pyridine scaffold. Furthermore, Cpd38 had a more altering effect on BRD4-BDI relative to Fgt47 which could also be as a result of its higher inhibitory activity.

CONCLUSION

Conclusively, the design of highly potent therapeutics could be facilitated by the incorporation of pharmacologically active small molecule fragments into the scaffold of existing drugs.

PERK Pathway and Neurodegenerative Disease: To Inhibit or to Activate?

With the extension of life span in recent decades, there is an increasing burden of late-onset neurodegenerative diseases, for which effective treatments are lacking. Neurodegenerative diseases include the widespread Alzheimer’s disease (AD) and Parkinson’s disease (PD), the less frequent Huntington’s disease (HD) and Amyotrophic Lateral Sclerosis (ALS) and also rare early-onset diseases linked to mutations that cause protein aggregation or loss of function in genes that maintain protein homeostasis. The difficulties in applying gene therapy approaches to tackle these diseases is drawing increasing attention to strategies that aim to inhibit cellular toxicity and restore homeostasis by intervening in cellular pathways. These include the unfolded protein response (UPR), activated in response to endoplasmic reticulum (ER) stress, a cellular affliction that is shared by these diseases. Special focus is turned to the PKR-like ER kinase (PERK) pathway of the UPR as a target for intervention. However, the complexity of the pathway and its ability to promote cell survival or death, depending on ER stress resolution, has led to some confusion in conflicting studies. Both inhibition and activation of the PERK pathway have been reported to be beneficial in disease models, although there are also some reports where they are counterproductive. Although with the current knowledge a definitive answer cannot be given on whether it is better to activate or to inhibit the pathway, the most encouraging strategies appear to rely on boosting some steps without compromising downstream recovery.

Structural alterations in the catalytic core of hSIRT2 enzyme predict therapeutic benefits of Garcinia mangostana derivatives in Alzheimer's disease: molecular dynamics simulation study

Recent studies have shown that inhibition of the hSIRT2 enzyme provides favorable effects in neurodegenerative diseases such as Alzheimer's disease. Prenylated xanthone phytochemicals including α-mangostin, β-mangostin and γ-mangostin obtained from Garcinia mangostana, a well-established tropical plant, have been shown experimentally to inhibit sirtuin enzymatic activity. However, the molecular mechanism of this sirtuin inhibition has not been reported. Using comprehensive integrated computational techniques, we provide molecular and timewise dynamical insights into the structural alterations capable of facilitating therapeutically beneficial effects of these phytochemicals at the catalytic core of the hSIRT2 enzyme. Findings revealed the enhanced conformational stability and compactness of the hSIRT2 catalytic core upon binding of γ-mangostin relative to the apoenzyme and better than α-mangostin and β-mangostin. Although thermodynamic calculations revealed favorable binding of all the phytochemicals to the hSIRT2 enzyme, the presence of only hydroxy functional groups on γ-mangostin facilitated the occurrence of additional hydrogen bonds involving Pro115, Phe119, Asn168 and His187 which are absent in α-mangostin- and β-mangostin-bound systems. Per-residue energy contributions showed that van der Waals and more importantly electrostatic interactions are involved in catalytic core stability with Phe96, Tyr104 and Phe235 notably contributing π-π stacking, π-π T shaped and π-sigma interactions. Cumulatively, our study revealed the structural alterations leading to inhibition of hSIRT2 catalysis and findings from this study could be significantly important for the future design and development of sirtuin inhibitors in the management of Alzheimer's disease.

A Mechanistic Probe into the Dual Inhibition of T. cruzi Glucokinase and Hexokinase in Chagas Disease Treatment - A Stone Killing Two Birds?

Glucokinase (GLK) and Hexokinase (HK) have been characterized as essential targets in Trypanosoma cruzi (Tc)-mediated infection. A recent study reported the propensity of the concomitant inhibition of TcGLK and TcHK by compounds GLK2-003 and GLK2-004, thereby presenting an efficient approach in Chagas disease treatment. We investigated this possibility using atomic and molecular scaling methods. Sequence alignment of TcGLK and TcHK revealed that both proteins shared approximately 33.3 % homology in their glucose/inhibitor binding sites. The total binding free energies of GLK2-003 and GLK2-004 were favorable in both proteins. PRO92 and THR185 were pivotal to the binding and stabilization of the ligands in TcGLK, likewise their conserved counterparts, PRO163 and THR237 in TcHK. Both compounds also induced a similar pattern of perturbations in both TcGLK and TcHK secondary structure. Findings from this study therefore provide insights into the underlying mechanisms of dual inhibition exhibited by the compounds. These results can pave way to discover and optimize novel dual Tc inhibitors with favorable pharmacokinetics properties eventuating in the mitigation of Chagas disease.

A probable means to an end: exploring P131 pharmacophoric scaffold to identify potential inhibitors of Cryptosporidium parvum inosine monophosphate dehydrogenase

Compound P131 has been established to inhibit Cryptosporidium parvum's inosine monophosphate dehydrogenase (CpIMPDH). Its inhibitory activity supersedes that of paromomycin, which is extensively used in treating cryptosporidiosis. Through the per-residue energy decomposition approach, crucial moieties of P131 were identified and subsequently adopted to create a pharmacophore model for virtual screening in the ZINC database. This search generated eight ADMET-compliant hits that were examined thoroughly to fit into the active site of CpIMPDH via molecular docking. Three compounds ZINC46542062, ZINC58646829, and ZINC89780094, with favorable docking scores of - 8.3 kcal/mol, - 8.2 kcal/mol, and - 7.5 kcal/mol, were selected. The potential inhibitory mechanism of these compounds was probed using molecular dynamics simulation and Molecular Mechanics Generalized Poisson Boltzmann Surface Area (MM/PBSA) analyses. Results revealed that one of the hits (ZINC46542062) exhibited a lower binding free energy of - 39.52 kcal/mol than P131, which had - 34.6 kcal/mol. Conformational perturbation induced by the binding of the identified hits to CpIMPDH was similar to P131, suggesting a similarity in inhibitory mechanisms. Also, in silico investigation of the properties of the hit compounds implied superior physicochemical properties with regards to their synthetic accessibility, lipophilicity, and number of hydrogen bond donors and acceptors in comparison with P131. ZINC46542062 was identified as a promising hit compound with the highest binding affinity to the target protein and favorable physicochemical and pharmacokinetic properties relative to P131. The identified compounds can serve as a basis for conducting further experimental investigations toward the development of anticryptosporidials, which can overcome the challenges of existing therapeutic options. Graphical abstract P131 and the identified compounds docked in the NAD⁺ binding site of Cryptosporidium parvum IMPDH.

'In silico' toxicology methods in drug safety assessment

While experimental animal investigation has historically been the most conventional approach conducted to assess drug safety and is currently considered the main method for determining drug toxicity, these studies are constricted by cost, time, and ethical approvals. Over the last 20 years, there have been significant advances in computational sciences and computer data processing, while knowledge of alternative techniques and their application has developed into a valuable skill in toxicology. Thus, the application of in silico methods in drug safety assessment is constantly increasing. They are very complex and are grounded on accumulated knowledge from toxicology, bioinformatics, biochemistry, statistics, mathematics, as well as molecular biology. This review will summarize current state-of-the-art scientific data on the use of in silico methods in toxicity testing, taking into account their shortcomings, and highlighting the strategies that should deliver consistent results, while covering the applications of in silico methods in preclinical trials and drug impurities toxicity testing.

Exploring the effect of ritonavir and TMC-310911 on SARS-CoV-2 and SARS-CoV main proteases: potential from a molecular perspective

AIM

As coronavirus (CoV) disease 2019-associated pneumonia spreads globally, there has been an urgent need to combat the spread and develop vaccines.

MATERIALS & METHODS

We used an integrated computational algorithm to explore the binding mechanism of TMC-310911/ritonavir (RVT) with SARS-CoV-2 and SARS-CoV main proteases.

RESULTS

RVT and TMC-310911 had favorable interactions with the proteases, and these high interactions are facilitated by some significant residues such as Asn133, Gly195 and Gln192. Our study further implicated two important rings in the structure of RVT as a possible chemical culprit in its therapeutic activity.

CONCLUSION

Although there are conflicting clinical results on the therapeutic potency of RVT in the treatment of coronavirus disease 2019, our findings provided molecular insight into the binding mechanism of TMC-310911 and RVT with SARS-CoV-2 and SARS-CoV main proteases.

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.

In Silico Repurposing of J147 for Neonatal Encephalopathy Treatment: Exploring Molecular Mechanisms of Mutant Mitochondrial ATP Synthase

BACKGROUND

Neonatal Encephalopathy (NE) is a mitochondrial ATP synthase (mATPase) disease, which results in the death of infants. The case presented here is reportedly caused by complex V deficiency as a result of mutation of Arginine to Cysteine at residue 329 in the mATPase. A recent breakthrough was the discovery of J147, which targets mATPase in the treatment of Alzheimer's disease. Based on the concepts of computational target-based drug design, this study investigated the possibility of employing J147 as a viable candidate in the treatment of NE.

OBJECTIVE/METHODS

The structural dynamic implications of this drug on the mutated enzyme are yet to be elucidated. Hence, integrative molecular dynamics simulations and thermodynamic calculations were employed to investigate the activity of J147 on the mutated enzyme in comparison to its already established inhibitory activity on the wild-type enzyme.

RESULTS

A correlated structural trend occurred between the wild-type and mutant systems whereby all the systems exhibited an overall conformational transition. Equal observations in favorable free binding energies further substantiated uniformity in the mobility, and residual fluctuation of the wild-type and mutant systems. The similarity in the binding landscape suggests that J147 could as well modulate mutant mATPase activity in addition to causing structural modifications in the wild-type enzyme.

CONCLUSION

Findings suggest that J147 can stabilize the mutant protein and restore it to a similar structural state as the wild-type which depicts functionality. These details could be employed in drug design for potential drug resistance cases due to mATPase mutations that may present in the future.

Early Detection of Alzheimer's Disease: Detecting Asymmetries with a Return Random Walk Link Predictor

Alzheimer's disease has been extensively studied using undirected graphs to represent the correlations of BOLD signals in different anatomical regions through functional magnetic resonance imaging (fMRI). However, there has been relatively little analysis of this kind of data using directed graphs, which potentially offer the potential to capture asymmetries in the interactions between different anatomical brain regions. The detection of these asymmetries is relevant to detect the disease in an early stage. For this reason, in this paper, we analyze data extracted from fMRI images using the net4Lap algorithm to infer a directed graph from the available BOLD signals, and then seek to determine asymmetries between the left and right hemispheres of the brain using a directed version of the Return Random Walk (RRW). Experimental evaluation of this method reveals that it leads to the identification of anatomical brain regions known to be implicated in the early development of Alzheimer's disease in clinical studies.

The Dual-Targeting Activity of the Metabolite Substrate of Para-amino Salicyclic Acid in the Mycobacterial Folate Pathway: Atomistic and Structural Perspectives

Therapeutic targeting of folate biosynthetic pathway has recently been explored as a viable strategy in the treatment of tuberculosis. The bioactive metabolite substrate of Para-amino salicyclic acid (PAS-M) reportedly dual-targets dihydrofolate reductase (DHFR) and flavin-dependent thymidylate synthase (FDTS), two essential enzymes in folate biosynthetic pathway. However, the molecular mechanisms and structural dynamics of this dual inhibitory activity of the PAS-M remain elusive. Molecular dynamics simulations revealed that binding of PAS-M towards DHFR is characterized by a recurrence of strong conventional hydrogen bond interactions between a peculiar DHFR binding site residue (Asp27) and the 2-amino-decahydropteridin-4-ol group of PAS-M. Similarly, the binding of PAS-M towards FDTS also involved consistent strong conventional hydrogen bond interactions between some specific residues (Tyr101, Arg172, Thr4, Gln103, Arg87 and Gln106) and, the 2-amino-decahydropteridin-4-ol group, thus establishing the cruciality of the group. Structural dynamics of the bound complexes of both enzymes revealed that, upon binding, PAS-M is anchored at the entrance of hydrophobic pockets by strong hydrogen bond interactions while the rest of the structure gains access to deeper hydrophobic residues to engage in favorable interactions. Further analysis of atomistic changes of both enzymes showed increased C-α atom deviations as well as an increase C-α atoms radius of gyration consistent with structural disorientations. These conformational changes possibly interfered with the biological functions of the enzymes and hence their inhibition as experimentally reported. Structural Insights provided could open up a novel paradigm of structure-based design of multi-targeting inhibitors of biological targets in the folate biosynthetic pathway toward tuberculosis therapy.

Exploring the ring potential of 2,4-diaminopyrimidine derivatives towards the identification of novel caspase-1 inhibitors in Alzheimer's disease therapy

Pro-inflammatory activation of caspase-1 in the neurodegenerative pathway has been associated with age-dependent cognitive impairment and Alzheimer's disease (AD) in humans. A recent report highlighted 2,4-diaminopyrimidine ring as an essential fragment in the inhibition of human caspase-1. However, the role of the ring and its enzyme inhibitory mechanism is not thoroughly investigated at the molecular level. The purpose of this study is therefore in twofold: (1) to understand the enzyme binding mechanism of the 2,4-diaminopyrimidine ring and (2) to search for more potent caspase-1 inhibitors that contain the ring, using integrative per-residue energy decomposition (PRED) pharmacophore modeling. Ligand interaction profile of a reference compound revealed a peculiar hydrogen formation of the amino group of 2,4-diaminopyrimidine with active site residue Arg341, possibly forming the bases for its inhibitory prowess against caspase-1. A generated pharmacophore model for structure-based virtual screening identified compounds, ZINC724667, ZINC09908119, and ZINC09933770, as potential caspase-1 inhibitors that possessed desirable pharmacokinetic and physiochemical properties. Further analyses revealed active site residues, Arg179, Ser236, Cys285, Gln283, Ser339, and Arg341, as crucial to inhibitor binding by stabilizing and forming hydrogen bonds, hydrophobic, and pi-pi interactions with the 2,4-diaminopyrimidine rings. Common interaction patterns of the hits could have accounted for their selective and high-affinity ligand binding, which was characterized by notable disruptions in caspase-1 structural architecture. These compounds could further be explored as potential leads in the development of novel caspase-1 inhibitors.

Can Medicinal Plants and Bioactive Compounds Combat Lipid Peroxidation Product 4-HNE-Induced Deleterious Effects?

The toxic reactive aldehyde 4-hydroxynonenal (4-HNE) belongs to the advanced lipid peroxidation end products. Accumulation of 4-HNE and formation of 4-HNE adducts induced by redox imbalance participate in several cytotoxic processes, which contribute to the pathogenesis and progression of oxidative stress-related human disorders. Medicinal plants and bioactive natural compounds are suggested to be attractive sources of potential agents to mitigate oxidative stress, but little is known about the therapeutic potentials especially on combating 4-HNE-induced deleterious effects. Of note, some investigations clarify the attenuation of medicinal plants and bioactive compounds on 4-HNE-induced disturbances, but strong evidence is needed that these plants and compounds serve as potent agents in the prevention and treatment of disorders driven by 4-HNE. Therefore, this review highlights the pharmacological basis of these medicinal plants and bioactive compounds to combat 4-HNE-induced deleterious effects in oxidative stress-related disorders, such as neurotoxicity and neurological disorder, eye damage, cardiovascular injury, liver injury, and energy metabolism disorder. In addition, this review briefly discusses with special attention to the strategies for developing potential therapies by future applications of these medicinal plants and bioactive compounds, which will help biological and pharmacological scientists to explore the new vistas of medicinal plants in combating 4-HNE-induced deleterious effects.

The Nrf2/HO-1 Axis as Targets for Flavanones: Neuroprotection by Pinocembrin, Naringenin, and Eriodictyol

Flavanones are a group of flavonoids that derive from their immediate chalcone precursors through the action of chalcone isomerase enzymes. The Aromatic A and B rings, C4-keto group, and the 15-carbon flavonoid skeleton are all evident in flavanones, but a notable absence of C2-C3 double bond and a lack of oxygenation at C-3 position of the C-ring makes them distinctively different from other groups such as flavonols (e.g., quercetin). On the basis of oxygenation level in the B ring, flavanones can vary from each other as exemplified by pinocembrin (no oxygenation), naringenin (4′-hydroxyl), or eriodictyol (3′,4′-dihydroxyl substitution). These groups are generally weaker free radical scavengers as compared to quercetin and derivatives though eriodictyol has a better free radical scavenging profile within the group due to the presence of the catechol functional moiety. In this communication, their antioxidant potential through the induction of antioxidant defenses is scrutinized. These compounds as exemplified by pinocembrin could induce the nuclear factor erythroid 2-related factor 2- (Nrf2-) heme oxygenase-1 (HO-1) axis leading to amelioration of oxidative stress in cellular and animal models. Their neuroprotective effect through such mechanism is discussed.

On the Neuroprotective Effects of Naringenin: Pharmacological Targets, Signaling Pathways, Molecular Mechanisms, and Clinical Perspective

As a group of progressive, chronic, and disabling disorders, neurodegenerative diseases (NDs) affect millions of people worldwide, and are on the rise. NDs are known as the gradual loss of neurons; however, their pathophysiological mechanisms have not been precisely revealed. Due to the complex pathophysiological mechanisms behind the neurodegeneration, investigating effective and multi-target treatments has remained a clinical challenge. Besides, appropriate neuroprotective agents are still lacking, which raises the need for new therapeutic agents. In recent years, several reports have introduced naturally-derived compounds as promising alternative treatments for NDs. Among natural entities, flavonoids are multi-target alternatives affecting different pathogenesis mechanisms in neurodegeneration. Naringenin is a natural flavonoid possessing neuroprotective activities. Increasing evidence has attained special attention on the variety of therapeutic targets along with complex signaling pathways for naringenin, which suggest its possible therapeutic applications in several NDs. Here, in this review, the neuroprotective effects of naringenin, as well as its related pharmacological targets, signaling pathways, molecular mechanisms, and clinical perspective, are described. Moreover, the need to develop novel naringenin delivery systems is also discussed to solve its widespread pharmacokinetic limitation.

Dysregulation of CRMP2 Post-Translational Modifications Drive Its Pathological Functions

Collapsin response mediator proteins (CRMPs) are a family of ubiquitously expressed, homologous phosphoproteins best known for coordinating cytoskeletal formation and regulating cellular division, migration, polarity, and synaptic connection. CRMP2, the most studied of the five family members, is best known for its affinity for tubulin heterodimers and function in regulating the microtubule network. These functions are tightly regulated by post-translational modifications including phosphorylation, SUMOylation, oxidation, and O-GlcNAcylation. While CRMP2's physiological functions rely mostly on its non-phosphorylated state, dysregulation of CRMP2 phosphorylation and SUMOylation has been reported to be involved in the pathophysiology of multiple diseases including cancer, chronic pain, spinal cord injury, neurofibromatosis type 1, and others. Here, we provide a consolidated update on what is known about CRMP2 signaling and function, first focusing on axonal growth and neuronal polarity, then illustrating the link between dysregulated CRMP2 post-translational modifications and diseases. We additionally discuss the roles of CRMP2 in non-neuronal cells, both in the CNS and regions of the periphery. Finally, we offer thoughts on the therapeutic implications of modulating CRMP2 function in a variety of diseases.

From the Explored to the Unexplored: Computer-Tailored Drug Design Attempts in the Discovery of Selective Caspase Inhibitors

The pathophysiological roles of caspases have made them attractive targets in the treatment and amelioration of neurologic diseases. In normal conditions, the expression of caspases is regulated in the brain, while at the onset of neurodegeneration, such as in Alzheimer's disease, they are typically overexpressed. Till date, several therapeutic efforts that include the use of small endogenous binders have been put forward to curtail dysfunctionalities that drive aberrant death in neuronal cells. Caspases are highly homologous, both in structure and in sequence, which leaves us with the question: is it possible to specifically and individually target caspases, while multiple therapeutic attempts to achieve selective targeting have failed! Based on antecedent events, the use of Computer-Aided Drug Design (CADD) methods has significantly contributed to the design of small molecule inhibitors, especially with selective target ability and reduced off-target therapeutic effects. Interestingly, we found out that there still exists an enormous room for the integration of structure/ligand-based drug design techniques towards the development of highly specific reversible and irreversible caspase inhibitors. Therefore, in this review, we highlight drug discovery approaches that have been directed towards caspase inhibition in addition to an insightful focus on applicable CADD techniques for achieving selective targeting in caspase research.

'Piperazining' the catalytic gatekeepers: unraveling the pan-inhibition of SRC kinases; LYN, FYN and BLK by masitinib

Aim: Blocking oncogenic signaling of B-cell receptor (BCR) has been explored as a viable strategy in the treatment of diffuse large B-cell lymphoma. Masitinib is shown to multitarget LYN, FYN and BLK kinases that propagate BCR signals to downstream effectors. However, the molecular mechanisms of its selectivity and pan-inhibition remain elusive. Materials & methods: This study therefore employed molecular dynamics simulations coupled with advanced post-molecular dynamics simulation techniques to unravel the structural mechanisms that inform the reported multitargeting ability of masitinib. Results: Molecular dynamics simulations revealed initial selective targeting of catalytic residues (Asp334/Glu335 - LYN; Asp130/Asp148/Glu54 - FYN; Asp89 - BLK) by masitinib, with high-affinity interactions via its piperazine ring at the entrance of the ATP-binding pockets, before systematic access into the hydrophobic deep pocket grooves. Conclusion: Identification of these 'gatekeeper' residues could open up a novel paradigm of structure-based design of highly selective pan-inhibitors of BCR signaling in the treatment of diffuse large B-cell lymphoma.

From genomic variation to protein aberration: Mutational analysis of single nucleotide polymorphism present in ULBP6 gene and implication in immune response

BACKGROUND

Genetic polymorphisms have been identified as one of the underlying factors in disease pathogenesis and drug resistance since they account for protein dysfunctionality, or in some cases, aberrancy. This explains the high degree of inactivity that characterizes the polymorphic variants of ULBP6 binding protein, which in turn disrupts its primary interaction with human Natural Killer Group 2-member D (NKG2D) and accounts for an impediment to immuno-surveillance. The possible identification of deleterious non-synonymous Single Nucleotide Polymorphisms (nsSNPs) present in the ULBP6 gene is essential for the development of novel gene therapies to prevent the translation of dysfunctional protein variants.

METHODS/RESULTS

In this study, for the first time, we employed an SNP-informatics approach (SNPs retrieval, pathogenic/mutational analysis, phenotypic analysis, and structural analysis) and molecular dynamics techniques to identify and characterize undesirable SNPs coupled with their impact on ULBP6 structural activities relative to dysfunctionality. V52F was predictively pathogenic amongst SNPs studied. Conformational and dynamic studies revealed that in comparison to wildtype ULBP6 (ULBP6^wt), pathogenic ULBP6^V52F demonstrated considerable structural inactivity, which could, in turn, impede biological protein-protein interactions. Moreover, ULBP6^V52F showed relatively limited motions in the conformational space as deduced from estimations of structural stability, fluctuations, and principal components.

CONCLUSION

This study provides a workable paradigm for investigating pathological nsSNPS using computational platforms which findings present ULBP6^V52F as a novel and attractive immunotherapeutic target in combatting immune-associated disorders.

Therapeutic potential of naringin in neurological disorders

Neurological illnesses are multifactorial incurable debilitating disorders that may cause neurodegeneration. These diseases influence approximately 30 million people around the world. Despite several therapies, effective management of such disorders remains a global challenge. Thus, natural products might offer an alternative therapy for the treatment of various neurological disorders. Polyphenols, such as curcumin, resveratrol, myricetin, mangiferin and naringin (NRG) have been shown to possess promising potential in the treatment of neurogenerative illness. In this review, we have targeted the therapeutic potential of naringin as a neuroprotective agent. The overall neuroprotective effects and different possible underlying mechanisms related to NRG are discussed. In light of the strong evidence for the neuropharmacological efficacy of NRG in various experimental paradigms, it is concluded that this molecule should be further considered and studied as a potential candidate for neurotherapeutics, focusing on mechanistic and clinical trials to ascertain its efficacy.

Deciphering the canonical blockade of activated Hageman factor (FXIIa) by benzamidine in the coagulation cascade: A thorough dynamical perspective

The experimental inhibitory potency of benzamidine (BEN) paved way for further design and development of inhibitors that target β-FXIIa. Structural dynamics of the loops and catalytic residues that encompass the binding pocket of β-FXIIa and all serine proteases are crucial to their overall activity. Employing molecular dynamics and post-MD analysis, this study sorts to unravel the structural and molecular events that accompany the inhibitory activity of BEN on human β-FXIIa upon selective non-covalent binding. Analysis of conformational dynamics of crucial loops revealed prominent alterations of the original conformational posture of FXIIa, evidenced by increased flexibility, decreased compactness, and an increased exposure to solvent upon binding of BEN, which could have in turn interfered with the essential roles of these loops in enhancing their procoagulation interactions with biological substrates and cofactors, altogether resulting in the consequential inactivation of FXIIa. A sustained interaction of the catalytic triad residues and key residues of the autolysis loop impeded their roles in catalysis which equally enhanced the inhibitory potency of BEN toward β-FXIIa evidenced by a favorable binding. Findings provide essential structural and molecular insights that could facilitate the structure-based design of novel antithrombotic compounds with enhanced inhibitory activities and low therapeutic risk.

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.

Effects and Underlying Mechanisms of Bioactive Compounds on Type 2 Diabetes Mellitus and Alzheimer's Disease

Type 2 diabetes mellitus is a complicated metabolic disorder characterized by hyperglycemia and glucose intolerance. Alzheimer's disease is a progressive brain disorder characterized by a chronic loss of cognitive and behavioral function. Considering the shared characteristics of both diseases, common therapeutic and preventive agents may be effective. Bioactive compounds such as polyphenols, vitamins, and carotenoids found in vegetables and fruits can have antioxidant and anti-inflammatory effects. These effects make them suitable candidates for the prevention or treatment of diabetes and Alzheimer's disease. Increasing evidence from cell or animal models suggest that bioactive compounds may have direct effects on decreasing hyperglycemia, enhancing insulin secretion, and preventing formation of amyloid plaques. The possible underlying molecular mechanisms are described in this review. More studies are needed to establish the clinical effects of bioactive compounds.

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.

An update on the discovery and development of selective heat shock protein inhibitors as anti-cancer therapy

INTRODUCTION

Over the years, not a single HSP inhibitor has progressed into the post-market phase of drug development despite the success recorded in various pre-clinical and clinical studies. The inability of existing drugs to specifically target oncogenic HSPs has majorly accounted for these setbacks. Recent combinatorial strategies that incorporated computer-aided drug design (CADD) techniques are geared towards the development of highly specific HSP inhibitors with increased activities and minimal toxicities. Areas covered: In this review, strategic therapeutic approaches that have recently aided the development of selective HSP inhibitors were highlighted. Also, the significant contributions of CADD techniques over the years were discussed in detail. This article further describes promising computational paradigms and their applications towards the discovery of highly specific inhibitors of oncogenic HSPs. Expert opinion: The recent shift towards highly selective and specific HSP inhibition has shown great promise as evidenced by the development of paralog/isoform-selective HSP drugs. It could be further augmented with computer-aided drug design strategies, which incorporate reliable methods that would greatly enhance the design and optimization of novel inhibitors with improved activities and minimal toxicities.