In Silico Screening of Isocitrate Lyase for Novel Anti-Buruli Ulcer Natural Products Originating from Africa

In silico drug repurposing of potential antiviral inhibitors targeting methyltransferase (2'-O-MTase) domain of Marburg virus

Marburg Virus (MARV) presents a significant threat to human health, highlighting the urgent need for effective therapeutics. The MARV genome encodes a multifunctional 'large' L protein that plays a crucial role in polymerase, capping, and methyltransferase activities. Within this protein, the 2'-O-methyltransferase (2'-O-MTase) domain is essential for viral replication and immune evasion, making it a promising therapeutic target. However, the lack of structural data on this domain limits drug discovery efforts. To address this challenge, we utilized AlphaFold2 to predict a 3D structure of the MARV 2'-O-MTase domain. Molecular docking with its natural ligand, S-adenosyl methionine (SAM), allowed us to identify key active-site residues involved in ligand binding. We then screened 62 known inhibitors against this domain and identified four promising candidates: Lifirafenib (- 9.5 kcal/mol), Dolutegravir (- 8.5 kcal/mol), BRD3969 (- 8.3 kcal/mol), and JFD00244 (- 8.2 kcal/mol). Further, we assessed the pharmacokinetic and pharmacodynamic properties of these compounds to evaluate their drug-likeness. Molecular dynamics simulations, along with MM/GBSA free energy calculations, confirmed stable interactions between the selected inhibitors and the target domain. While these findings highlight promising candidates for MARV, experimental validation through in vitro and in vivo assays is essential to assess their safety and efficacy.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s40203-025-00355-z.

Computational and GC-MS screening of bioactive compounds from Thymus Vulgaris targeting mycolactone protein associated with Buruli ulcer

Buruli ulcer (BU) a neglected disease induced by the bacterium Mycobacterium ulcerans, predominantly impacts tropical and subtropical areas with its pathophysiology ascribed to the Mycolactone protein. Current antibiotics frequently prove insufficient to manage advanced or chronic ulcers and the rise of drug resistance presents a considerable challenge. This work aims to address these challenges by employing computational methods to identify therapeutic candidates from organic compounds, which may be developed into more effective therapies for Buruli ulcer. The Gas-Chromatography Mass Spectrometry (GCMS) analysis of the Thymus Vulgaris identified the 29 bioactive compounds as potential drug candidates having different medicinal properties. Out of the 29 compounds against the mycolactone protein, 14 compounds demonstrated a binding affinity higher than - 6 kcal/mol predicted through PyRx. Among all compounds, gamma sitosterol and borneol showed the highest binding affinity - 7.7 kcal/mol. The ADMET analysis predicted that the compound borneol crosses the PGP + through the Blood Brain Barrier and gastrointestinal tract without violating Lipinski's rule of 5 having high water solubility, and log p-value of 2.29. The molecular dynamic simulation was performed and showed the Eigenvalue of 1.332692e-04. The leads identified in the study have demonstrated encouraging outcomes with regard to their efficacy, toxicity, pharmacokinetics, and safety. Further experimental investigations can be conducted to evaluate their anti-bacterial activity, and their molecular frameworks could be utilized as a valuable foundation for designing new drugs for the treatment of Buruli ulcer.

Gallic Acid: A Potent Metabolite Targeting Shikimate Kinase in Acinetobacter baumannii

Background/Objectives:Acinetobacter baumannii is a highly multidrug-resistant pathogen resistant to almost all classes of antibiotics; new therapeutic strategies against this infectious agent are urgently needed. Shikimate kinase is an enzyme belonging to the shikimate pathway and has become a potential target for drug development. This work describes the search for Food and Drug Administration (FDA)-approved drugs and natural compounds, including gallic acid, that could be repurposed as selective shikimate kinase inhibitors by integrated computational and experimental approaches. Methods: Approaches to drug design using structure-based and ligand-based methodology, in-silico screening, molecular docking, and molecular dynamics for the study of both binding affinity and stability. Experimental Validation Determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) on Acinetobacter baumannii and Enterococcus faecalis. Results/Conclusions: Among them, gallic acid, obtained from plants, proved to be the most promising compound that showed sufficient binding with shikimate kinase through computational studies. Gallic acid showed very good activity against Acinetobacter baumannii and Enterococcus faecalis in the MIC and MBC assay, respectively. Gallic acid exhibited better activity against Acinetobacter baumannii due to the overexpression of shikimate kinase. Gallic acid has emerged as a potential therapeutic candidate drug against A. baumannii infection and, therefore, as a strategy against the appearance of multidrug-resistant microorganisms. This study not only identifies a novel repurposing opportunity for gallic acid but also provides a comprehensive computational and experimental framework for accelerating antimicrobial drug discovery against multidrug-resistant pathogens.

Discovery of Non-Peptide GLP-1 Positive Allosteric Modulators from Natural Products: Virtual Screening, Molecular Dynamics, ADMET Profiling, Repurposing, and Chemical Scaffolds Identification

Background/Objectives: Glucagon-like peptide-1 (GLP-1) receptor is currently one of the most explored targets exploited for the management of diabetes and obesity, with many aspects of its mechanisms behind cardiovascular protection yet to be fully elucidated. Research dedicated towards the development of oral GLP-1 therapy and non-peptide ligands with broader clinical applications is crucial towards unveiling the full therapeutic capacity of this potent class of medicines. Methods: This study describes the virtual screening of a natural product database consisting of 695,133 compounds for positive GLP-1 allosteric modulation. The database, obtained from the Coconut website, was filtered according to a set of physicochemical descriptors, then was shape screened against the crystal ligand conformation. This filtered database consisting of 26,325 compounds was used for virtual screening against the GLP-1 allosteric site. Results: The results identified ten best hits with the XP score ranging from -9.6 to -7.6 and MM-GBSA scores ranging from -50.8 to -32.4 and another 58 hits from docked pose filter and a second round of XP docking and MM-GBSA calculation followed by molecular dynamics. The analysis of results identified hits from various natural products (NPs) classes, to whom attributed antidiabetic and anti-obesity effects have been previously reported. The results also pointed to β-lactam antibiotics that may be evaluated in drug repurposing studies for off-target effects. The calculated ADMET properties for those hits revealed suitable profiles for further development in terms of bioavailability and toxicity. Conclusions: The current study identified several NPs as potential GLP-1 positive allosteric modulators and revealed common structural scaffolds including peptidomimetics, lactams, coumarins, and sulfonamides with peptidomimetics being the most prominent especially in indole and coumarin cores.

In Silico Design of CT26 Polytope and its Surface Display by ClearColi™-Derived Outer Membrane Vesicles as a Cancer Vaccine Candidate Against Colon Carcinoma

Simultaneous targeting of several mutations can be useful in colorectal cancer (CRC) due to its heterogeneity and presence of somatic mutations. As CT26 mutations and expression profiles resemble those of human CRC, we focused on designing a polyepitope vaccine based on CT26 neoepitopes. Due to its low immunogenicity, outer membrane vesicles (rOMV) as an antigen delivery system and adjuvant was applied. Herein, based on previous experimental and our in silico studies four CT26 neoepitopes with the ability to bind MHC-I and MHC-II, TCR, and induce IFN-α production were selected. To increase their immunogenicity, the gp70 and PADRE epitopes were added. The order of the neoepitopes was determined through 3D structure analysis using ProSA, Verify 3D, ERRAT, and Ramachandran servers. The stable peptide-protein docking between the selected epitopes and MHC alleles strengthen our prediction. The CT26 polytope vaccine sequence was fused to the C-terminal of cytolysin A (ClyA) anchor protein and rOMVs were isolated from endotoxin-free ClearColi™ strain. The results of the C-ImmSim server showed that the ClyA-CT26 polytope vaccine could induce T and B cells immunity.The ClyA-CT26 polytope was characterized as a soluble, stable, immunogen, and non-allergen vaccine and optimized for expression in ClearColi™ 24 h after induction with 1 mM IPTG at 25 °C. Western blot analysis confirmed the expression of ClyA-CT26 polytope by ClearColi™ and also on ClearColi™-derived rOMVs. In conclusion, we found that ClearColi™-derived rOMVs with CT26 polytope can deliver CRC neoantigens and induce antitumor immunity, but in vivo immunological studies are needed to confirm vaccine efficacy.

Synthesis and antiproliferative activity of 2-oxo-3-phenylquinoxaline derivatives and related compounds against colon cancer

We have designed 17 new 2-oxo-3-phenylquinoxalines via the chemoselective Michael reaction of 3-phenylquinoxalin-2(1H)-one with acrylic acid derivatives. The ester, ethyl 3-(2-oxo-3-phenylquinoxalin-1(2H)-yl)propanoate, was reacted with hydroxylamine and hydrazine to produce N-hydroxy-3-(2-oxo-3-phenylquinoxalin-1(2H)-yl)propanamide and hydrazide, respectively. Further modifications were made through reactions with isothiocyanates and azide coupling with amines, yielding thiosemicarbazides and N-alkyl derivatives. Molecular docking studies identified compound 7j as the most potent binder, fitting well into the active site, with the phenyl ring occupying the S1 pocket and the amino acid chain positioned in the S2 pocket. The synthesized compounds (2a, 4, 7a, 7g, 7d, 7h, 7e, 7b, 7c, 7f, and 7j) were evaluated for their anti-cancer activity on colorectal cancer (HCT-116) cells. Compounds 2a and 7j showed significant reductions in cell viability, with IC50 values of 28.85 ± 3.26 μg mL-1 and 26.75 ± 3.50 μg mL-1, respectively. Image analysis of HCT-116 cells treated with 60 μg mL-1 of compound 7j for 48 hours revealed notable morphological changes in both nuclei and cells. The number of cells reduced from 447 in the control to 238 in the treated group, with a corresponding reduction in the area covered by cells from 41.9% to 17.6%. Nuclear disintegration and chromatin fragmentation were observed, confirming apoptosis. These results highlight the potent cytotoxic effect of compound 7j.

Exploring Marine-Derived Compounds: In Silico Discovery of Selective Ketohexokinase (KHK) Inhibitors for Metabolic Disease Therapy

The increasing prevalence of metabolic diseases, including nonalcoholic fatty liver disease (NAFLD), obesity, and type 2 diabetes, poses significant global health challenges. Ketohexokinase (KHK), an enzyme crucial in fructose metabolism, is a potential therapeutic target due to its role in these conditions. This study focused on the discovery of selective KHK inhibitors using in silico methods. We employed structure-based drug design (SBDD) and ligand-based drug design (LBDD) approaches, beginning with molecular docking to identify promising compounds, followed by induced-fit docking (IFD), molecular mechanics generalized Born and surface area continuum solvation (MM-GBSA), and molecular dynamics (MD) simulations to validate binding affinities. Additionally, shape-based screening was conducted to assess structural similarities. The findings highlight several potential inhibitors with favorable ADMET profiles, offering promising candidates for further development in the treatment of fructose-related metabolic disorders.

Cheminformatics-enhanced discovery of therapeutic agents targeting isocitrate lyase in Mycobacterium tuberculosis infections

Tuberculosis (TB) is a global health challenge; therefore, there is an urgent requirement to develop a novel and more effective anti-TB therapeutic. This study targeted the isocitrate lyase (ICL) protein due to its pivotal role in the pathogenicity of Mycobacterium tuberculosis (Mtb). Virtual screening of 8752 bioactive compounds used an ML-based QSAR model and molecular docking. ADMET testing was performed on the top three hits to identify the compound most closely mimicking a drug molecule. The top hits, 648 and 2785758, showed high binding affinity towards ICL with -7.3 and -7 kcal/mol, comparable to the control. These molecules also showed strong binding with the residue Asp108, which plays a vital role in ICL activity. Molecular dynamics simulations showed stability for 648 and 2785758, comparable to the control compound used in this study. It was found that 648 bound to the protein maintained the RMSD constant and consistent at 0.3 nm for a complete 100 ns simulation. 2785758 showed a comparable RMSD trend to the control. Both 648 and 2785758 showed high RMSF for critical residue Asp108. Further, PCA and FEL confirmed the formation of a stable complex. MM/GBSA estimations of binding free energy indicated that compounds 648 had an elevated level of stability (ΔGTOTAL = -28.11 kcal/mol) and 2785758 (ΔGTOTAL = -21.05 kcal/mol). This study suggests that compounds 648 and 2785758 can potentially affect the activity of ICL, leading to its inactivation and ultimately preventing the progression of tuberculosis.Communicated by Ramaswamy H. Sarma.

Molecular characterization, expression and in-silico analysis of fibrinogen-related protein 1 (frep1) in malaria vector Anopheles stephensi

BACKGROUND

Fibrinogen-related protein 1 (frep1) is a member of the pattern-recognizing receptor family (PRR) which generates an innate immune response after recognizing the pattern associated molecular pattern (PAMP) that occurs on the surface of microorganisms. The main objective of this study is to characterize frep1 and its in-silico analysis in Anopheles stephensi.

METHODS AND RESULT

The DNA was extracted from female Anopheles stephensi. PCR was performed for complete analysis of frep1 using specific primers. The gene sequence of frep1 was identified by Sanger sequencing. The bioinformatics structure analysis approach revealed the presence of 3 exons and 4 introns in the frep1. The sequence of frep1 was submitted to NCBI GeneBank with accession number ON817187.1. Quantitative real-time PCR was performed to analyze frep1 expression. At the developmental stage, frep1 is highly expressed in the L1 stage, egg, and adult female mosquito. In addition, frep1 is highly expressed in the tissue fat body, midgut, and salivary gland. After blood-fed, an upregulation of frep1 at 48 h in the midgut, and downregulation in fat body were observed at different time intervals.

CONCLUSION

The genomic data of frep1 is encoded by 12,443 bp. The frep1 has a significant role in the early metamorphosis. Its expression in fat body and midgut suggests it could be important for fat metabolism and post-blood digestion. The conserved domain could be targeted for vector control. Further study is required to elucidate its function against malaria parasites to confirm its agonist role in malaria transmission.

Computational exploration of SLC14A1 genetic variants through structure modeling, protein-ligand docking, and molecular dynamics simulation

The urea transporter UT-B1, encoded by the SLC14A1 gene, has been hypothesized to be a significant protein whose deficiency and dysfunction contribute to the pathogenesis of bladder cancer and many other diseases. Several studies reported the association of genetic alterations in the SLC14A1 (UT-B1) gene with bladder carcinogenesis, suggesting a need for thorough characterization of the UT-B1 protein's coding and non-coding variants. This study used various computational techniques to investigate the commonly occurring germ-line missense and non-coding SNPs (ncSNPs) of the SLC14A1 gene (UT-B1) for their structural, functional, and molecular implications for disease susceptibility and dysfunctionality. SLC14A1 missense variants, primarily identified from the ENSEMBL genome browser, were screened through twelve functionality prediction tools leading to two variants D280Y (predicted detrimental by maximum tools) and D280N (high global MAF) for rs1058396. Subsequently, the ConSurf and NetSurf tools revealed the D280 residue to be in a variable site and exposed on the protein surface. According to I-Mutant2.0 and MUpro, both variants are predicted to cause a significant effect on protein stability. Analysis of molecular docking anticipated these two variants to decrease the binding affinity of UT-B1 protein for the examined ligands to a significant extent. Molecular dynamics also disclosed the possible destabilization of the UT-B1 protein due to single nucleotide polymorphism compared to wild-type protein which may result in impaired protein function. Furthermore, several non-coding SNPs were estimated to affect transcription factor binding and regulation of SLC14A1 gene expression. Additionally, two ncSNPs were found to affect miRNA-based post-transcriptional regulation by creating new seed regions for miRNA binding. This comprehensive in-silico study of SLC14A1 gene variants may serve as a springboard for future large-scale investigations examining SLC14A1 polymorphisms.

Anti-Infective Activity of Momordica charantia Extract with Molecular Docking of Its Triterpenoid Glycosides

Momordica charantia, commonly known as bitter melon, is a fruiting plant that has been used for several diseases including infectious diseases. In this study, we report the antibacterial, antifungal, and antiviral activity of different bitter melon fruit parts originating from India and Saudi Arabia. The in vitro experiments are supported by the molecular docking of karavilosides to verify their role in the bioactivity. The antimicrobial assays revealed activity against Candida albicans, Escherichia coli, and Staphylococcus aureus. The extracts exhibited the potent inhibition of HIV-I reverse transcriptase, with an IC50 of 0.125 mg/mL observed for the pith extract originating from Saudi Arabia and the standard drug doxorubicin. The molecular docking of karavilosides exhibited a significant affinity to reverse transcriptase comparable to Rilpivirine and higher than that of doxorubicin. These outcomes encourage the precious bioactive components of the seed and pith of the Saudi bitter melon fruits to be further studied for isolation and structure elucidation.

Analysis of highly frequent point mutations in glycoprotein C, glycoprotein N, and nucleoprotein of CCHFV

Crimean-Congo hemorrhagic fever virus (CCHFV) is classified among top 10 priority pathogens by World Health Organization. CCHFV belongs to Bunyaviridae family and negative sense ssRNA genome composed of three RNA segments: L, M, and S. RNA viruses show higher mutation rate as compared to DNA viruses. To gain deeper understanding of impact of point mutations in CCHFV M and S segment, mutation profiling, homology modeling, and molecular dynamic (MD) simulation were performed. Structural glycoproteins (glycoprotein C [Gc] and glycoprotein N [Gn]) of CCHFV are important for host-virus interaction and genome packaging, whereas CCHFV nucleoprotein (NP) is crucial for viral replication. Hence, current study is focused on evaluation of eight mutations in structural glycoproteins (Gc: 7 and Gn: 1) of M segment and seven mutations in NP of S segment. All these mutations were highly frequent, with mutation frequency between 0.81 and 1.0 and found to be persistent in the recent strains of CCHFV. Solubility analysis predicted that selected point mutations reduce solubility of Gc protein and increase solubility of Gn and NP proteins. MD simulation study deciphered that A1046V and G1158E in Gc protein, I778T in Gn protein, and H195R in NP protein displayed large deviation and fluctuation, and affected intramolecular interactions. In conclusion, we observed that point mutations could impact structure, stability, and host-virus interaction of protein, and might lead to evolution of new strains for better survival and drug resistance.

Sulfadiazine Exerts Potential Anticancer Effect in HepG2 and MCF7 Cells by Inhibiting TNFα, IL1b, COX-1, COX-2, 5-LOX Gene Expression: Evidence from In Vitro and Computational Studies

Drug repurposing is a promising approach that has the potential to revolutionize the drug discovery and development process. By leveraging existing drugs, we can bring new treatments to patients more quickly and affordably. Anti-inflammatory drugs have been shown to target multiple pathways involved in cancer development and progression. This suggests that they may be more effective in treating cancer than drugs that target a single pathway. Cell viability was measured using the MTT assay. The expression of genes related to inflammation (TNFa, IL1b, COX-1, COX-2, and 5-LOX) was measured in HepG2, MCF7, and THLE-2 cells using qPCR. The levels of TNFα, IL1b, COX-1, COX-2, and 5-LOX were also measured in these cells using an ELISA kit. An enzyme binding assay revealed that sulfadiazine expressed weaker inhibitory activity against COX-2 (IC50 = 5.27 μM) in comparison with the COX-2 selective reference inhibitor celecoxib (COX-2 IC50 = 1.94 μM). However, a more balanced inhibitory effect was revealed for sulfadiazine against the COX/LOX pathway with greater affinity towards 5-LOX (IC50 = 19.1 μM) versus COX-1 (IC50 = 18.4 μM) as compared to celecoxib (5-LOX IC50 = 16.7 μM, and COX-1 IC50 = 5.9 μM). MTT assays revealed the IC50 values of 245.69 ± 4.1 µM and 215.68 ± 3.8 µM on HepG2 and MCF7 cell lines, respectively, compared to the standard drug cisplatin (66.92 ± 1.8 µM and 46.83 ± 1.3 µM, respectively). The anti-inflammatory effect of sulfadiazine was also depicted through its effect on the levels of inflammatory markers and inflammation-related genes (TNFα, IL1b, COX-1, COX-2, 5-LOX). Molecular simulation studies revealed key binding interactions that explain the difference in the activity profiles of sulfadiazine compared to celecoxib. The results suggest that sulfadiazine exhibited balanced inhibitory activity against the 5-LOX/COX-1 enzymes compared to the selective COX-2 inhibitor, celecoxib. These findings highlight the potential of sulfadiazine as a potential anticancer agent through balanced inhibitory activity against the COX/LOX pathway and reduction in the expression of inflammatory genes.

Design of Inhibitors That Target the Menin-Mixed-Lineage Leukemia Interaction

The prognosis of mixed-lineage leukemia (MLL) has remained a significant health concern, especially for infants. The minimal treatments available for this aggressive type of leukemia has been an ongoing problem. Chromosomal translocations of the KMT2A gene are known as MLL, which expresses MLL fusion proteins. A protein called menin is an important oncogenic cofactor for these MLL fusion proteins, thus providing a new avenue for treatments against this subset of acute leukemias. In this study, we report results using the structure-based drug design (SBDD) approach to discover potential novel MLL-mediated leukemia inhibitors from natural products against menin. The three-dimensional (3D) protein model was derived from Protein Databank (Protein ID: 4GQ4), and EasyModeller 4.0 and I-TASSER were used to fix missing residues during rebuilding. Out of the ten protein models generated (five from EasyModeller and I-TASSER each), one model was selected. The selected model demonstrated the most reasonable quality and had 75.5% of residues in the most favored regions, 18.3% of residues in additionally allowed regions, 3.3% of residues in generously allowed regions, and 2.9% of residues in disallowed regions. A ligand library containing 25,131 ligands from a Chinese database was virtually screened using AutoDock Vina, in addition to three known menin inhibitors. The top 10 compounds including ZINC000103526876, ZINC000095913861, ZINC000095912705, ZINC000085530497, ZINC000095912718, ZINC000070451048, ZINC000085530488, ZINC000095912706, ZINC000103580868, and ZINC000103584057 had binding energies of -11.0, -10.7, -10.6, -10.2, -10.2, -9.9, -9.9, -9.9, -9.9, and -9.9 kcal/mol, respectively. To confirm the stability of the menin-ligand complexes and the binding mechanisms, molecular dynamics simulations including molecular mechanics Poisson-Boltzmann surface area (MM/PBSA) computations were performed. The amino acid residues that were found to be potentially crucial in ligand binding included Phe243, Met283, Cys246, Tyr281, Ala247, Ser160, Asn287, Asp185, Ser183, Tyr328, Asn249, His186, Leu182, Ile248, and Pro250. MI-2-2 and PubChem CIDs 71777742 and 36294 were shown to possess anti-menin properties; thus, this justifies a need to experimentally determine the activity of the identified compounds. The compounds identified herein were found to have good pharmacological profiles and had negligible toxicity. Additionally, these compounds were predicted as antileukemic, antineoplastic, chemopreventive, and apoptotic agents. The 10 natural compounds can be further explored as potential novel agents for the effective treatment of MLL-mediated leukemia.

Buruli ulcer in Africa: Geographical distribution, ecology, risk factors, diagnosis, and indigenous plant treatment options - A comprehensive review

Buruli ulcer (BU), a neglected tropical disease (NTD), is an infection of the skin and subcutaneous tissue caused by Mycobacterium ulcerans. The disease has been documented in many South American, Asian, and Western Pacific countries and is widespread throughout much of Africa, especially in West and Central Africa. In rural areas with scarce medical care, BU is a devastating disease that can leave patients permanently disabled and socially stigmatized. Mycobacterium ulcerans is thought to produce a mycolactone toxin, which results in necrosis of the afflicted tissue and may be involved in the etiology of BU. Initially, patients may notice a painless nodule or plaque on their skin; as the disease progresses, however, it may spread to other parts of the body, including the muscles and bones. Clinical signs, microbial culture, and histological analysis of afflicted tissue all contribute to a diagnosis of BU. Though antibiotic treatment and surgical removal of infected tissue are necessary for BU management, plant-derived medicine could be an alternative in areas with limited access to conventional medicine. Herein we reviewed the geographical distribution, socioeconomic, risk factors, diagnosis, biology and ecology of the pathogen. Complex environmental, socioeconomic, and genetic factors that influence BU are discussed. Further, our review highlights future research areas needed to develop strategies to manage the disease through the use of indigenous African plants.

Antiemetic effects of sclareol, possibly through 5-HT3 and D2 receptor interaction pathways: In-vivo and in-silico studies

BACKGROUND

Emesis is a complex physiological phenomenon that serves as a defense against numerous toxins, stressful situations, adverse medication responses, chemotherapy, and movement. Nevertheless, preventing emesis during chemotherapy or other situations is a significant issue for researchers. Hence, the majority view contends that successfully combining therapy is the best course of action. In-vivo analysis offers a more comprehensive grasp of how compounds behave within a complex biological environment, whereas in-silico evaluation refers to the use of computational models to forecast biological interactions.

OBJECTIVES

The objectives of the present study were to evaluate the effects of Sclareol (SCL) on copper sulphate-induced emetic chicks and to investigate the combined effects of these compounds using a conventional co-treatment approach and in-silico study.

METHODS

SCL (5, 10, and 15 mg/kg) administered orally with or without pre-treatment with anti-emetic drugs (Ondansetron (ODN): 24 mg/kg, Domperidone (DOM): 80 mg/kg, Hyoscine butylbromide (HYS): 100 mg/kg, and Promethazine hydrochloride (PRO): 100 mg/kg) to illustrate the effects and the potential involvement with 5HT3, D2, M3/AChM, H1, or NK1 receptors by SCL. Furthermore, an in-silico analysis was conducted to forecast the role of these receptors in the emetic process.

RESULTS

The results suggest that SCL exerted a dose-dependent anti-emetic effect on the chicks. Pretreatment with SCL-10 significantly minimized the number of retches and lengthened the emesis tendency of the experimental animals. SCL-10 significantly increased the anti-emetic effects of ODN and DOM. However, compared to the ODN-treated group, (SCL-10 + ODN) group considerably (p < 0.0001) extended the latency duration (109.40 ± 1.03 s) and significantly (p < 0.01) decreased the number of retches (20.00 ± 0.70), indicating an anti-emetic effect on the test animals. In in-silico analysis, SCL exhibited promising binding affinities with suggesting receptors.

CONCLUSION

SCL-10 exerted an inhibitory-like effect on emetic chicks, probably through the interaction of the 5HT3 and D2 receptors. Further studies are highly appreciated to validate this study and determine the precise mechanism(s) behind the anti-emetic effects of SCL. We expect that SCL-10 may be utilized as an antiemetic treatment in a single dosage form or that it may function as a synergist with other traditional medicines.

Computational exploration and design of a multi-epitopes vaccine construct against Chlamydia psittaci

Chlamydia psittaci is an intracellular pathogen and causes variety of deadly infections in humans. Antibiotics are effective against C. psittaci however high percentage of resistant strains have been reported in recent times. As there is no licensed vaccine, we used in-silico techniques to design a multi-epitopes vaccine against C. psittaci. Following a step-wise protocol, the proteome of available 26 strains was retrieved and filtered for subcellular localized proteins. Five proteins were selected (2 extracellular and 3 outer membrane) and were further analyzed for B-cell and T-cell epitopes prediction. Epitopes were further checked for antigenicity, solubility, stability, toxigenicity, allergenicity, and adhesive properties. Filtered epitopes were linked via linkers and the 3D structure of the designed vaccine construct was predicted. Binding of the designed vaccine with immune receptors: MHC-I, MHC-II, and TLR-4 was analyzed, which resulted in docking energy scores of -4.37 kcal/mol, -0.20 kcal/mol and -22.38 kcal/mol, respectively. Further, the docked complexes showed stable dynamics with a maximum value of vaccine-MHC-I complex (7.8 Å), vaccine-MHC-II complex (6.2 Å) and vaccine-TLR4 complex (5.2 Å). As per the results, the designed vaccine construct reported robust immune responses to protect the host against C. psittaci infections. In the study, the C. psittaci proteomes were considered in pan-genome analysis to extract core proteins. The pan-genome analysis was conducted using bacterial pan-genome analysis (BPGA) software. The core proteins were checked further for non-redundant proteins using a CD-Hit server. Surface localized proteins were investigated using PSORTb v 3.0. The surface proteins were BLASTp against Virulence Factor Data Base (VFDB) to predict virulent factors. Antigenicity prediction of the shortlisted proteins was further done using VAXIGEN v 2.0. The epitope mapping was done using the immune epitope database (IEDB). A multi-epitopes vaccine was built and a 3D structure was generated using 3Dprot online server. The docking analysis of the designed vaccine with immune receptors was carried out using PATCHDOCK. Molecular dynamics and post-simulation analyses were carried out using AMBER v20 to decipher the dynamics stability and intermolecular binding energies of the docked complexes.Communicated by Ramaswamy H. Sarma.

Molecular Docking and Dynamics Simulation Studies Predict Potential Anti-ADAR2 Inhibitors: Implications for the Treatment of Cancer, Neurological, Immunological and Infectious Diseases

Altered RNA editing has been linked to several neurodevelopmental disorders, including autism spectrum disorder (ASD) and intellectual disability, in addition to depression, schizophrenia, some cancers, viral infections and autoimmune disorders. The human ADAR2 is a potential therapeutic target for managing these various disorders due to its crucial role in adenosine to inosine editing. This study applied consensus scoring to rank potential ADAR2 inhibitors after performing molecular docking with AutoDock Vina and Glide (Maestro), using a library of 35,161 compounds obtained from traditional Chinese medicine. A total of 47 compounds were predicted to be good binders of the human ADAR2 and had insignificant toxicity concerns. Molecular dynamics (MD) simulations, including the molecular mechanics Poisson-Boltzmann surface area (MM/PBSA) procedure, also emphasized the binding of the shortlisted compounds. The potential compounds had plausible binding free energies ranging from -81.304 to -1068.26 kJ/mol from the MM/PBSA calculations. ZINC000085511995, a naphthoquinone had more negative binding free energy (-1068.26 kJ/mol) than inositol hexakisphosphate (IHP) [-873.873 kJ/mol], an agonist and a strong binder of ADAR2. The potential displacement of IHP by ZINC000085511995 in the IHP binding site of ADAR2 could be explored for possible deactivation of ADAR2. Bayesian-based biological activity prediction corroborates the neuropharmacological, antineoplastic and antiviral activity of the potential lead compounds. All the potential lead compounds, except ZINC000014612330 and ZINC000013462928, were predicted to be inhibitors of various deaminases. The potential lead compounds also had probability of activity (Pa) > 0.442 and probability of inactivity (Pi) < 0.116 values for treating acute neurologic disorders, except for ZINC000085996580 and ZINC000013462928. Pursuing these compounds for their anti-ADAR2 activities holds a promising future, especially against neurological disorders, some cancers and viral infections caused by RNA viruses. Molecular interaction, hydrogen bond and per-residue decomposition analyses predicted Arg400, Arg401, Lys519, Trp687, Glu689, and Lys690 as hot-spot residues in the ADAR2 IHP binding site. Most of the top compounds were observed to have naphthoquinone, indole, furanocoumarin or benzofuran moieties. Serotonin and tryptophan, which are beneficial in digestive regulation, improving sleep cycle and mood, are indole derivatives. These chemical series may have the potential to treat neurological disorders, prion diseases, some cancers, specific viral infections, metabolic disorders and eating disorders through the disruption of ADAR2 pathways. A total of nine potential lead compounds were shortlisted as plausible modulators of ADAR2.

Design of multi-epitope based vaccine against Mycobacterium tuberculosis: a subtractive proteomics and reverse vaccinology based immunoinformatics approach

Tuberculosis is an airborne transmissible disease caused by Mycobacterium tuberculosis that infects millions of lives worldwide. There is still no single comprehensive therapy or preventative available for the lethal illness. Currently, the available vaccine, BCG is ineffectual in preventing the prophylactic adult pulmonary TB and reactivation of latent tuberculosis. Therefore, this investigation was intended to design a new multi-epitope vaccine that can address the existing problems. The subtractive proteomics approach was implemented to prioritize essential, virulence, druggable, and antigenic proteins as suitable vaccine candidates. Furthermore, a reverse vaccinology-based immunoinformatics technique was employed to identify potential B-cell, helper T lymphocytes (HTL), and cytotoxic T lymphocytes (CTL) epitopes from the target proteins. Immune-stimulating adjuvant, linkers, and PADRE (Pan HLA-DR epitopes) amino acid sequences along with the selected epitopes were used to construct a chimeric multi-epitope vaccine. The molecular docking and normal mode analysis (NMA) were carried out to evaluate the binding mode of the designed vaccine with different immunogenic receptors (MHC-I, MHC-II, and Tlr4). In addition, the MD simulation, followed by essential dynamics study and MMPBSA analysis, was carried out to understand the dynamics and stability of the complexes. In-silico cloning was accomplished using E.coli as an expression system to express the designed vaccine successfully. Finally, the immune simulation study has foreseen that our designed vaccine could induce a significant immune response by elevation of different immunoglobulins in the host. However, there is an imperative need for the experimental validation of the designed vaccine in animal models to confer effectiveness and safety.HIGHLIGHTSMulti-epitope based vaccine was designed against Mycobacterium tuberculosis using subtractive proteomics and Immunoinformatics approach.The vaccine was found to be antigenic, non-allergenic, immunogenic, and stable based on in-silico prediction.Population coverage analysis of the proposed vaccine predicts an effective response in the world population.The molecular docking, MD simulation, and MM-PBSA study confirm the stable interaction of the vaccine with immunogenic receptors.In silico cloning and immune simulation of the vaccine demonstrated its successful expression in E.coli and induction of immune response in the host. Communicated by Ramaswamy H. Sarma.

Molecular modeling, simulation and docking of Rv1250 protein from Mycobacterium tuberculosis

Computational prediction and protein structure modeling have come to the aid of various biological problems in determining the structure of proteins. These technologies have revolutionized the biological world of research, allowing scientists and researchers to gain insights into their biological questions and design experimental research much more efficiently. Pathogenic Mycobacterium spp. is known to stay alive within the macrophages of its host. Mycobacterium tuberculosis is an acid-fast bacterium that is the most common cause of tuberculosis and is considered to be the main cause of resistance of tuberculosis as a leading health issue. The genome of Mycobacterium tuberculosis contains more than 4,000 genes, of which the majority are of unknown function. An attempt has been made to computationally model and dock one of its proteins, Rv1250 (MTV006.22), which is considered as an apparent drug-transporter, integral membrane protein, and member of major facilitator superfamily (MFS). The most widely used techniques, i.e., homology modeling, molecular docking, and molecular dynamics (MD) simulation in the field of structural bioinformatics, have been used in the present work to study the behavior of Rv1250 protein from M. tuberculosis. The structure of unknown TB protein, i.e., Rv1250 was retrived using homology modeling with the help of I-TASSER server. Further, one of the sites responsible for infection was identified and docking was done by using the specific Isoniazid ligand which is an inhibitor of this protein. Finally, the stability of protein model and analysis of stable and static interaction between protein and ligand molecular dynamic simulation was performed at 100 ns The designing of novel Rv1250 enzyme inhibitors is likely achievable with the use of proposed predicted model, which could be helpful in preventing the pathogenesis caused by M. tuberculosis. Finally, the MD simulation was done to evaluate the stability of the ligand for the specific protein.

Integrated Bioinformatics-Based Subtractive Genomics Approach to Decipher the Therapeutic Drug Target and Its Possible Intervention against Brucellosis

Brucella suis, one of the causative agents of brucellosis, is Gram-negative intracellular bacteria that may be found all over the globe and it is a significant facultative zoonotic pathogen found in livestock. It may adapt to a phagocytic environment, reproduce, and develop resistance to harmful environments inside host cells, which is a crucial part of the Brucella life cycle making it a worldwide menace. The molecular underpinnings of Brucella pathogenicity have been substantially elucidated due to comprehensive methods such as proteomics. Therefore, we aim to explore the complete Brucella suis proteome to prioritize the novel proteins as drug targets via subtractive proteo-genomics analysis, an effort to conjecture the existence of distinct pathways in the development of brucellosis. Consequently, 38 unique metabolic pathways having 503 proteins were observed while among these 503 proteins, the non-homologs (n = 421), essential (n = 350), drug-like (n = 114), virulence (n = 45), resistance (n = 42), and unique to pathogen proteins were retrieved from Brucella suis. The applied subsequent hierarchical shortlisting resulted in a protein, i.e., isocitrate lyase, that may act as potential drug target, which was finalized after the extensive literature survey. The interacting partners for these shortlisted drug targets were identified through the STRING database. Moreover, structure-based studies were also performed on isocitrate lyase to further analyze its function. For that purpose, ~18,000 ZINC compounds were screened to identify new potent drug candidates against isocitrate lyase for brucellosis. It resulted in the shortlisting of six compounds, i.e., ZINC95543764, ZINC02688148, ZINC20115475, ZINC04232055, ZINC04231816, and ZINC04259566 that potentially inhibit isocitrate lyase. However, the ADMET profiling showed that all compounds fulfill ADMET properties except for ZINC20115475 showing positive Ames activity; whereas, ZINC02688148, ZINC04259566, ZINC04232055, and ZINC04231816 showed hepatoxicity while all compounds were observed to have no skin sensitization. In light of these parameters, we recommend ZINC95543764 compound for further experimental studies. According to the present research, which uses subtractive genomics, proteins that might serve as therapeutic targets and potential lead options for eradicating brucellosis have been narrowed down.

Consensus docking and MM-PBSA computations identify putative furin protease inhibitors for developing potential therapeutics against COVID-19

The coronavirus disease 2019 (COVID-19) is a pandemic that has severely posed substantial health challenges and claimed millions of lives. Though vaccines have been produced to stem the spread of this disease, the death rate remains high since drugs used for treatment have therapeutic challenges. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes the disease, has a slew of potential therapeutic targets. Among them is the furin protease, which has a cleavage site on the virus’s spike protein. The cleavage site facilitates the entry of the virus into human cells via cell–cell fusion. This critical involvement of furin in the disease pathogenicity has made it a viable therapeutic strategy against the virus. This study employs the consensus docking approach using HYBRID and AutoDock Vina to virtually screen a pre-filtered library of 3942 natural product compounds of African origin against the human furin protease (PDB: 4RYD). Twenty of these compounds were selected as hits after meeting molecular docking cut-off of − 7 kcal.mol⁻¹, pose alignment inspection, and having favorable furin-ligand interactions. An area under the curve (AUC) value of 0.72 was computed from the receiver operator characteristic (ROC) curve, and Boltzmann-enhanced discrimination of the ROC curve (BEDROC) value of 0.65 showed that AutoDock Vina was a reasonable tool for selecting actives for this target. Seven of these hits were proposed as potential leads having had bonding interactions with catalytic triad residues Ser368, His194, and Asp153, and other essential residues in the active site with plausible binding free energies between − 189 and − 95 kJ/mol from the Molecular Mechanics Poisson-Boltzmann Surface Area (MM-PBSA) calculations as well as favorable ADME/Tox properties. The molecules were also predicted as antiviral, anti-inflammatory, membrane permeability inhibitors, RNA synthesis inhibitors, cytoprotective, and hepatoprotective with probable activity (Pa) above 0.5 and probable inactivity values below 0.1. Some of them also have anti-influenza activity. Influenza virus has many similarities with SARS-CoV-2 in their mode of entry into human cells as both are facilitated by the furin protease. Pinobanksin 3-(E)-caffeate, one of the potential leads is a propolis compound. Propolis compounds have shown inhibitory effects against ACE2, TMPRSS2, and PAK1 signaling pathways of SARS-CoV-2 in previous studies. Likewise, quercitrin is structurally similar to isoquercetin, which is currently in clinical trials as possible medication for COVID-19.

Molecular Modelling and Atomistic Insights into the Binding Mechanism of MmpL3 Mtb

Mycobacterial membrane proteins Large (MmpLs), which belong to the resistance, nodulation, and division (RND) protein superfamily, play critical roles in transporting polymers, lipids, and immunomodulators. MmpLs have become one of the important therapeutic drug targets to emerge in recent times. In this study, two homology modelling techniques, Modeller and SWISS-MODEL, were used in modelling the three-dimensional protein structure of the MmpL3 of Mycobacterium tuberculosis using that of M. smegmatis as template. MmpL3 inhibitors, namely BM212, NITD304, SPIRO, and NITD349, in addition to the co-crystalized ligands AU1235, ICA38, SQ109 and rimonabant, were screened against the modelled structure and the Mmpl3 of M. smegmatis using molecular docking techniques. Protein-ligand interactions were analysed using molecular dynamics simulations and Molecular Mechanics Poisson-Boltzmann surface area computations. Novel residues Gln32, Leu165, Ile414, and Phe35 were identified as critical for binding to M. tuberculosis MmpL3, and conformational dynamics upon inhibitor binding were discussed.

Density Functional Theory-Based Studies Predict Carbon Nanotubes as Effective Mycolactone Inhibitors

Fullerenes, boron nitride nanotubes (BNNTs), and carbon nanotubes (CNTs) have all been extensively explored for biomedical purposes. This work describes the use of BNNTs and CNTs as mycolactone inhibitors. Density functional theory (DFT) has been used to investigate the chemical properties and interaction mechanisms of mycolactone with armchair BNNTs (5,5) and armchair CNTs (5,5). By examining the optimized structure and interaction energy, the intermolecular interactions between mycolactone and nanotubes were investigated. The findings indicate that mycolactone can be physically adsorbed on armchair CNTs in a stable condition, implying that armchair CNTs can be potential inhibitors of mycolactone. According to DOS plots and HOMO–LUMO orbital studies, the electronic characteristics of pure CNTs are not modified following mycolactone adsorption on the nanotubes. Because of mycolactone’s large π-π interactions with CNTs, the estimated interaction energies indicate that mycolactone adsorption on CNTs is preferable to that on BNNTs. CNTs can be explored as potentially excellent inhibitors of mycolactone toxins in biological systems.

Computer-aided identification of potential inhibitors against Necator americanus glutathione S-transferase 3

Hookworm infection is caused by the blood-feeding hookworm gastrointestinal nematodes. Its harmful effects include anemia and retarded growth and are common in the tropics. A current control method involves the mass drug administration of synthetic drugs, mainly albendazole and mebendazole. There are however concerns of low efficacy and drug resistance due to their repeated and excessive use. Although, Necator americanus glutathione S-transferase 3 (Na-GST-3) is a notable target, using natural product libraries for computational elucidation of promising leads is underexploited. This study sought to use pharmacoinformatics techniques to identify compounds of natural origins with the potential to be further optimized as promising inhibitors. A compendium of 3182 African natural products together with five known helminth GST inhibitors including Cibacron blue was screened against the active sites of the Na-GST-3 structure (PDB ID: 3W8S). The hit compounds were profiled to ascertain the mechanisms of binding, anthelmintic bioactivity, physicochemical and pharmacokinetic properties. The AutoDock Vina docking protocol was validated by obtaining 0.731 as the area under the curve calculated via the receiver operating characteristics curve. Four compounds comprising ZINC85999636, ZINC35418176, ZINC14825190, and Dammarane Triterpene13 were identified as potential lead compounds with binding energies less than -9.0 kcal/mol. Furthermore, the selected compounds formed key intermolecular interactions with critical residues Tyr95, Gly13 and Ala14. Notably, ZINC85999636, ZINC14825190, and dammarane triterpene13 were predicted as anthelmintics, whilst all the four molecules shared structural similarities with known inhibitors. Molecular modelling showed that the compounds had reasonably good binding free energies. More so, they had high binding affinities when screened against other variants of the Na-GST, namely Na-GST-1 and Na-GST-2. Ligand quality assessment using ligand efficiency dependent lipophilicity, ligand efficiency, ligand efficiency scale and fit quality scale showed the molecules are worthy candidates for further optimization. The inhibitory potentials of the molecules warrant in vitro studies to evaluate their effect on the heme regulation mechanisms.

Prediction of potential cysteine synthase inhibitors of Leishmania braziliensis and Leishmania major parasites by computational screening

Leishmaniasis is a neglected tropical disease considered a public health problem that requires innovative strategies for its chemotherapeutic control. In the present investigation, a molecular docking approach was carried out using the protein cysteine synthase (CS) of Leishmania braziliensis (CSLb) and Leishmania major (CSLm) parasites to identify new compounds as potential candidates for the development of selective leishmaniasis therapy. CS protein sequence similarity, active site, structural modeling, molecular docking, and ADMET properties of compounds were analyzed using bioinformatics tools. Molecular docking analyses identified 1000 ligands with highly promising binding affinity scores for both CS proteins. A total of 182 compounds for CSLb and 173 for CSLm were selected for more detailed characterization based on the binding energy and frequency values and ADMET properties. Based on Principal Component Analysis (PCA) and K-means clusterization for both CS proteins, we classified compounds into 5 clusters for CSLb and 7 for CSLm, thus providing an excellent starting point for verification of enzyme inhibition in in vitro studies. We found the ZINC16524774 compound predicted to have a high affinity and stability for both CSLb and CSLm proteins, which was also evaluated through molecular dynamics simulations. Compounds within each of the five clusters also displayed pharmacological and structural properties that make them attractive drug candidates for the development of selective cutaneous leishmaniasis chemotherapy.

Thiazole-Chalcone Hybrids as Prospective Antitubercular and Antiproliferative Agents: Design, Synthesis, Biological, Molecular Docking Studies and In Silico ADME Evaluation

Compounds bearing thiazole and chalcone pharmacophores have been reported to possess excellent antitubercular and anticancer activities. In view of this, we designed, synthesized and characterized a novel series of thiazole-chalcone hybrids (1-20) and further evaluated them for antitubercular and antiproliferative activities by employing standard protocols. Among the twenty compounds, chalcones 12 and 7, containing 2,4-difluorophenyl and 2,4-dichlorophenyl groups, showed potential antitubercular activity higher than the standard pyrazinamide (MIC = 25.34 µM) with MICs of 2.43 and 4.41 µM, respectively. Chalcone 20 containing heteroaryl 2-thiazolyl moiety exhibited promising antiproliferative activity against the prostate cancer cell line (DU-145), higher than the standard methotrexate (IC50 = 11 ± 1 µM) with an IC50 value of 6.86 ± 1 µM. Furthermore, cytotoxicity studies of these compounds against normal human liver cell lines (L02) revealed that the target molecules were comparatively less selective against L02. Additional computational studies using AutoDock predicted the key binding interactions responsible for the activity and the SwissADME tool computed the in silico drug likeliness properties. The lead compounds generated through this study, create a way for the optimization and development of novel drugs against tuberculosis infections and prostate cancer.

Cheminformatics-Based Identification of Potential Novel Anti-SARS-CoV-2 Natural Compounds of African Origin

The coronavirus disease 2019 (COVID-19) pandemic caused by the severe acute respiratory syndrome virus 2 (SARS-CoV-2) has impacted negatively on public health and socioeconomic status, globally. Although, there are currently no specific drugs approved, several existing drugs are being repurposed, but their successful outcomes are not guaranteed. Therefore, the search for novel therapeutics remains a priority. We screened for inhibitors of the SARS-CoV-2 main protease and the receptor-binding domain of the spike protein from an integrated library of African natural products, compounds generated from machine learning studies and antiviral drugs using AutoDock Vina. The binding mechanisms between the compounds and the proteins were characterized using LigPlot+ and molecular dynamics simulations techniques. The biological activities of the hit compounds were also predicted using a Bayesian-based approach. Six potential bioactive molecules NANPDB2245, NANPDB2403, fusidic acid, ZINC000095486008, ZINC0000556656943 and ZINC001645993538 were identified, all of which had plausible binding mechanisms with both viral receptors. Molecular dynamics simulations, including molecular mechanics Poisson-Boltzmann surface area (MM/PBSA) computations revealed stable protein-ligand complexes with all the compounds having acceptable free binding energies <-15 kJ/mol with each receptor. NANPDB2245, NANPDB2403 and ZINC000095486008 were predicted as antivirals; ZINC000095486008 as a membrane permeability inhibitor; NANPDB2403 as a cell adhesion inhibitor and RNA-directed RNA polymerase inhibitor; and NANPDB2245 as a membrane integrity antagonist. Therefore, they have the potential to inhibit viral entry and replication. These drug-like molecules were predicted to possess attractive pharmacological profiles with negligible toxicity. Novel critical residues identified for both targets could aid in a better understanding of the binding mechanisms and design of fragment-based de novo inhibitors. The compounds are proposed as worthy of further in vitro assaying and as scaffolds for the development of novel SARS-CoV-2 therapeutic molecules.

Leishmanicidal Potential of Hardwickiic Acid Isolated From Croton sylvaticus

Leishmania is a parasitic protozoon responsible for the neglected tropical disease Leishmaniasis. Approximately, 350 million people are susceptible and close to 70,000 death cases globally are reported annually. The lack of effective leishmanicides, the emergence of drug resistance and toxicity concerns necessitate the pursuit for effective antileishmanial drugs. Natural compounds serve as reservoirs for discovering new drugs due to their chemical diversity. Hardwickiic acid (HA) isolated from the stembark of Croton sylvaticus was evaluated for its leishmanicidal potential against Leishmania donovani and L. major promastigotes. The susceptibility of the promastigotes to HA was determined using the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide/phenazine methosulfate colorimetric assay with Amphotericin B serving as positive control. HA showed a significant antileishmanial activity on L. donovani promastigotes with an IC₅₀ value of 31.57± 0.06 µM with respect to the control drug, amphotericin B with IC₅₀ of 3.35 ± 0.14 µM). The cytotoxic activity was observed to be CC₅₀ = 247.83 ± 6.32 µM against 29.99 ± 2.82 µM for curcumin, the control, resulting in a selectivity index of SI = 7.85. Molecular modeling, docking and dynamics simulations of selected drug targets corroborated the observed antileishmanial activity of HA. Novel insights into the mechanisms of binding were obtained for trypanothione reductase (TR), pteridine reductase 1 (PTR1), and glutamate cysteine ligase (GCL). The binding affinity of HA to the drug targets LmGCL, LmPTR1, LdTR, LmTR, LdGCL, and LdPTR1 were obtained as -8.0, -7.8, -7.6, -7.5, -7.4 and -7.1 kcal/mol, respectively. The role of Lys16, Ser111, and Arg17 as critical residues required for binding to LdPTR1 was reinforced. HA was predicted as a Caspase-3 stimulant and Caspase-8 stimulant, implying a possible role in apoptosis, which was shown experimentally that HA induced parasite death by loss of membrane integrity. HA was also predicted as antileishmanial molecule corroborating the experimental activity. Therefore, HA is a promising antileishmanial molecule worthy of further development as a biotherapeutic agent.

Pharmacoinformatics-based identification of potential bioactive compounds against Ebola virus protein VP24

BACKGROUND

The impact of Ebola virus disease (EVD) is devastating with concomitant high fatalities. Currently, various drugs and vaccines are at different stages of development, corroborating the need to identify new therapeutic molecules. The VP24 protein of the Ebola virus (EBOV) plays a key role in the pathology and replication of the EVD. The VP24 protein interferes with the host immune response to viral infections and promotes nucleocapsid formation, thus making it a viable drug target. This study sought to identify putative lead compounds from the African flora with potential to inhibit the activity of the EBOV VP24 protein using pharmacoinformatics and molecular docking.

METHODS

An integrated library of 7675 natural products originating from Africa obtained from the AfroDB and NANPDB databases, as well as known inhibitors were screened against VP24 (PDB ID: 4M0Q) utilising AutoDock Vina after energy minimization using GROMACS. The top 19 compounds were physicochemically and pharmacologically profiled using ADMET Predictor™, SwissADME and DataWarrior. The mechanisms of binding between the molecules and EBOV VP24 were characterised using LigPlot+. The performance of the molecular docking was evaluated by generating a receiver operating characteristic (ROC) by screening known inhibitors and decoys against EBOV VP24. The prediction of activity spectra for substances (PASS) and machine learning-based Open Bayesian models were used to predict the anti-viral and anti-Ebola activity of the molecules, respectively.

RESULTS

Four natural products, namely, ZINC000095486070, ZINC000003594643, ZINC000095486008 and sarcophine were found to be potential EBOV VP24-inhibitiory molecules. The molecular docking results showed that ZINC000095486070 had high binding affinity of -9.7 kcal/mol with EBOV VP24, which was greater than those of the known VP24-inhibitors used as standards in the study including Ouabain, Nilotinib, Clomiphene, Torimefene, Miglustat and BCX4430. The area under the curve of the generated ROC for evaluating the performance of the molecular docking was 0.77, which was considered acceptable. The predicted promising molecules were also validated using induced-fit docking with the receptor using Schrödinger and molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) calculations. The molecules had better binding mechanisms and were pharmacologically profiled to have plausible efficacies, negligible toxicity as well as suitable for designing anti-Ebola scaffolds. ZINC000095486008 and sarcophine (NANPDB135) were predicted to possess anti-viral activity, while ZINC000095486070 and ZINC000003594643 to be anti-Ebola compounds.

CONCLUSION

The identified compounds are potential inhibitors worthy of further development as EBOV biotherapeutic agents. The scaffolds of the compounds could also serve as building blocks for designing novel Ebola inhibitors.

Molecular Informatics Studies of the Iron-Dependent Regulator (ideR) Reveal Potential Novel Anti-Mycobacterium ulcerans Natural Product-Derived Compounds

Buruli ulcer is a neglected tropical disease caused by the bacterium Mycobacterium ulcerans. Its virulence is attributed to the dermo-necrotic polyketide toxin mycolactone, whose synthesis is regressed when its iron acquisition system regulated by the iron-dependent regulator (ideR) is deactivated. Interfering with the activation mechanism of ideR to inhibit the toxin’s synthesis could serve as a possible cure for Buruli ulcer. The three-dimensional structure of the ideR for Mycobacterium ulcerans was generated using homology modeling. A library of 832 African natural products (AfroDB), as well as five known anti-mycobacterial compounds were docked against the metal binding site of the ideR. The area under the curve (AUC) values greater than 0.7 were obtained for the computed Receiver Operating Characteristics (ROC) curves, validating the docking protocol. The identified top hits were pharmacologically profiled using Absorption, Distribution, Metabolism, Elimination and Toxicity (ADMET) predictions and their binding mechanisms were characterized. Four compounds with ZINC IDs ZINC000018185774, ZINC000095485921, ZINC000014417338 and ZINC000005357841 emerged as leads with binding energies of −7.7 kcal/mol, −7.6 kcal/mol, −8.0 kcal/mol and −7.4 kcal/mol, respectively. Induced Fit Docking (IFD) was also performed to account for the protein’s flexibility upon ligand binding and to estimate the best plausible conformation of the complexes. Results obtained from the IFD were consistent with that of the molecular docking with the lead compounds forming interactions with known essential residues and some novel critical residues Thr14, Arg33 and Asp17. A hundred nanoseconds molecular dynamic simulations of the unbound ideR and its complexes with the respective lead compounds revealed changes in the ideR’s conformations induced by ZINC000018185774. Comparison of the lead compounds to reported potent inhibitors by docking them against the DNA-binding domain of the protein also showed the lead compounds to have very close binding affinities to those of the potent inhibitors. Interestingly, structurally similar compounds to ZINC000018185774 and ZINC000014417338, as well as analogues of ZINC000095485921, including quercetin are reported to possess anti-mycobacterial activity. Also, ZINC000005357841 was predicted to possess anti-inflammatory and anti-oxidative activities, which are relevant in Buruli ulcer and iron acquisition mechanisms, respectively. The leads are molecular templates which may serve as essential scaffolds for the design of future anti-mycobacterium ulcerans agents.