MMV 1804559 is a potential antistaphylococcal and antibiofilm agent targeting the clfA gene of Staphylococcus aureus.

AIM: Staphylococcus aureus, a high-priority pathogen proclaimed to cause infections ranging from mild to life-threatening, presents significant challenges in treatment. New therapies can be developed quicker using open drug discovery platforms offering a distinct approach to expedite the development of innovative antibacterial and anti-biofilm therapeutics. This study set out to address these issues by finding new uses for current medications to find compounds that are effective against S. aureus. METHODS AND RESULTS: In this study, we screened the global priority health box, launched by Medicines for Malaria Ventures containing 240 compounds, for their effectiveness against S. aureus. MMV1795508, MMV1542799, MMV027331, MMV1593278, and MMV1804559 showed potential antibacterial activity at 10 µM concentration. These compounds underwent further evaluation for their ability to clear intracellular bacteria, disrupt biofilm formation and eradicate existing biofilms. MMV1804559 demonstrated strong efficacy across all tested parameters, achieving 94% inhibition of intracellular bacteria, 79.19% disruption of biofilm cells, and 66.18% inhibition of biofilm formation. Scanning electron microscopy revealed notable membrane perforations and blebbing in MMV1804559-treated cells, indicating its impact on bacterial membranes. Gene expression analysis of cells treated with MMV1804559 showed downregulation of clfA and clfB genes, critical for biofilm formation. Additionally, docking studies confirmed the binding affinity of MMV1804559 with clfA, supported by favorable docking scores, MM/GBSA binding energy, and increased hydrogen bond interactions in the binding pocket, suggesting clfA as a target for MMV1804559. CONCLUSION: MMV1804559 could serve as a potential therapy for S. aureus by targeting biofilm development and cell adhesion processes.

Unveiling the potential of marine compounds as quorum sensing inhibitors targeting Pseudomonas aeruginosa's LasI: A computational study using molecular docking and molecular dynamics.

Antimicrobial resistance (AMR) poses a significant threat to global public health, with multidrug-resistant Pseudomonas aeruginosa being a leading cause of mortality, accounting for 18%-61% of deaths annually. The quorum sensing (QS) systems of P. aeruginosa, particularly the LasI-LasR system, play a crucial role in promoting biofilm formation and expression of virulent genes, which contribute to the development of AMR. This study focuses on LasI, the mediator of biofilm formation for identifying its inhibitors from a marine compound database comprising of 32 000 compounds using molecular docking and molecular simulation techniques. The virtual screening and docking experiments demonstrated that the top 10 compounds exhibited favorable docking scores of <-7.19 kcal/mol compared to the reported inhibitor 3,5,7-Trihydroxyflavone with a docking score of -3.098 kcal/mol. Additionally, molecular mechanics/Poisson-Boltzmann generalized born surface area (MM-GBSA) analyses were conducted to assess these compounds' suitability for further investigation. Out of 10 compounds, five compounds demonstrated high MM-GBSA binding energy (<-35.33 kcal/mol) and were taken up for molecular dynamics simulations to evaluate the stability of the protein-ligand complex over a 100 ns period. Based on root mean square deviation, root mean square fluctuation, radius of gyration, and hydrogen bond interactions analysis, three marine compounds, namely MC-2 (CMNPD13419) and MC-3 (CMNPD1068), exhibited consistent stability throughout the simulation. Therefore, these compounds show potential as promising LasI inhibitors and warrant further validation through in vitro and in vivo experiments. By exploring the inhibitory effects of these marine compounds on P. aeruginosa's QS system, this research aims to contribute to the development of novel strategies to combat AMR.

Artemisinin derivatives induce oxidative stress leading to DNA damage and caspase-mediated apoptosis in Theileria annulata-transformed cells.

BACKGROUND: Bovine theileriosis caused by the eukaryotic parasite Theileria annulata is an economically important tick-borne disease. If it is not treated promptly, this lymphoproliferative disease has a significant fatality rate. Buparvaquone (BPQ) is the only chemotherapy-based treatment available right now. However, with the emergence of BPQ resistance on the rise and no backup therapy available, it is critical to identify imperative drugs and new targets against Theileria parasites. METHODS: Artemisinin and its derivatives artesunate (ARS), artemether (ARM), or dihydroartemisinin (DHART) are the primary defence line against malaria parasites. This study has analysed artemisinin and its derivatives for their anti-Theilerial activity and mechanism of action. RESULTS: ARS and DHART showed potent activity against the Theileria-infected cells. BPQ in combination with ARS or DHART showed a synergistic effect. The compounds act specifically on the parasitised cells and have minimal cytotoxicity against the uninfected host cells. Treatment with ARS or DHART induces ROS-mediated oxidative DNA damage leading to cell death. Further blocking intracellular ROS by its scavengers antagonised the anti-parasitic activity of the compounds. Increased ROS production induces oxidative stress and DNA damage causing p53 activation followed by caspase-dependent apoptosis in the Theileria-infected cells. CONCLUSIONS: Our findings give unique insights into the previously unknown molecular pathways underpinning the anti-Theilerial action of artemisinin derivatives, which may aid in formulating new therapies against this deadly parasite. Video abstract.

Linezolid resistant coagulase negative staphylococci (LRCoNS) with novel mutations causing blood stream infections (BSI) in India.

BACKGROUND: Coagulase-negative Staphylococci (CoNS) have emerged as a major causative agent of blood-stream infections (BSI). Linezolid (LZD) is currently used for treating glycopeptide and methicillin-resistant staphylococci. It is important to understand the resistance mechanism and probable transmission of LZD resistant (LR) CoNS within the hospital. METHODS: Clinically significant LRCoNS from patients with BSI were characterized using MALDI-TOF and 16S rRNA gene sequence analysis. Antimicrobial susceptibility and MIC of vancomycin and LZD were determined. LZD resistance mechanisms using PCR for the cfr gene and mutation in the V domain of the 23S rRNA gene were studied. RESULTS: The MIC of LZD ranged from 8 to 32 µg/ml. LR was observed in three different CoNS species from diverse locations within the hospital. The cfr gene was identified in all the isolates. Sequence analysis of V domain region of 23S rRNA gene confirmed mutation in single copy among 12/15 isolates with novel mutations: G2614 T and C2384T. All infections were nosocomially acquired and LZD resistance was emerging in the absence of prior LZD use. Horizontal spread of resistant isolates and cfr gene among diverse species were the probable mechanisms of transmission. CONCLUSION: The study highlights the novel mutations associated with LRCoNS and the importance of surveillance & transmission pathway within the hospital. It also systematically discusses the published information on LRCoNS.

Elucidation of cellular mechanisms involved in experimental paromomycin resistance in Leishmania donovani.

Leishmania donovani is the causative agent of the potentially fatal disease visceral leishmaniasis (VL). Chemotherapeutic options available to treat VL are limited and often face parasite resistance, inconsistent efficacy, and toxic side effects. Paromomycin (PMM) was recently introduced to treat VL as a monotherapy and in combination therapy. It is vital to understand the mechanisms of PMM resistance to safeguard the drug. In the present study, we utilized experimentally generated PMM-resistant L. donovani to elucidate the mechanisms of resistance and parasite biology. We found increased membrane fluidity accompanied by decreased intracellular drug accumulation in the PMM-resistant parasites. There were marked increases in gene expression of ATP-binding cassette (ABC) transporters (MDR1 and MRPA) and protein phosphatase 2A that evince increased drug efflux. Further, evaluation of parasite tolerance toward host leishmanicidal mechanisms revealed PMM-resistant parasites as being more tolerant to nitrosative stress at the promastigote and amastigote stages. The PMM-resistant parasites also predicted a better survival capacity, as indicated by resistance to complement-mediated lysis and increased stimulation of host interleukin-10 (IL-10) expression. The susceptibilities of PMM-resistant isolates to other antileishmanial agents (sodium antimony gluconate and miltefosine) remained unchanged. The data implicated the roles of altered membrane fluidity, decreased drug accumulation, increased expression of ABC transporters, and greater tolerance of parasites to host defense mechanisms in conferring PMM resistance in Leishmania.

Computational assessment of marine natural products as LasR inhibitors for attenuating quorum sensing in Pseudomonas aeruginosa.

The Quorum Sensing (QS) system in bacteria has become a focal point for researchers aiming to develop novel antimicrobials to combat multidrug-resistant bacteria. Pseudomonas aeruginosa, an opportunistic Gram-negative bacterium, has developed resistance against a variety of antimicrobial agents, making it a formidable pathogen responsible for nosocomial infections. QS system mainly controls the expression of genes responsible for biofilm formation and virulence of bacteria. Within the QS system of P. aeruginosa, the transcription activator LasR plays a pivotal role and is an appealing target for the development of antimicrobial agents. In this study, we employed molecular docking and molecular dynamics simulations to identify potential inhibitors of LasR by screening marine natural products (MNPs) from the CMNPD database. We identified ten MNPs with excellent docking scores (less than -11.7 kcal/mol) against LasR, surpassing the binding energy of the co-crystal 3-oxo-C12-HSL (-8.594 kcal/mol) and the reference compound cladodionen (-6.71 kcal/mol). Furthermore, we selected five of these MNPs with the highest MM/GBSA binding energies for extensive 100 ns molecular simulations to assess their stability. The molecular dynamics simulations indicated three MNPs, namely CMNPD10886, CMNPD20987, and CMNPD20960, maintained high stability throughout the 100 ns simulation period, as evidenced by their root mean square deviation, root mean square fluctuation, radius of gyration, and hydrogen bond interactions within the ligand-protein complex analysis. Furthermore, essential dynamics (PCA and DCCM) were performed to analyse the correlated motion of amino acids. These findings suggest that these compounds hold potential as inhibitors of LasR, offering promising prospects for the development of treatments against infections.Communicated by Ramaswamy H. Sarma.

Repurposing of Food and Drug Admnistration (FDA) approved library to identify a potential inhibitor of trypanothione synthetase for developing an antileishmanial agent.

Leishmaniasis is one of the top 10 neglected tropical diseases. Globally, it impacts more than 12 million individuals. In light of the absence of a safer, affordable treatment for the Leishmaniasis, along with therapeutic failures and drug resistance, novel therapeutic strategies are necessary to discover new drugs. Treatment would benefit by concentrating on the precise targets that are crucial for the parasite to survive. A target that aids in the organism's survival under oxidative stress is trypanothione synthetase (TyS), which is a component of the trypanothione pathway in Leishmania spp. To find potential TyS inhibitors for the purpose of discovering novel antileishmanial drugs, we used a virtual screening strategy. Using the Glide module of Schrodinger-suite 2023, an FDA-approved library containing 2000 drugs from the ZINC-15 database was screened against the TyS. Dostinex, raloxifene, and formoterol showed good docking scores of -10.568 kcal/mol, -10.446 kcal/mol, and -56.21 kcal/mol, as well as good binding energies of -70.41 kcal/mol, -56.21 kcal/mol, and -64.15 kcal/mol respectively. The stability of the ligand-protein complexes was assessed further with the help of Desmond to execute a 100-ns molecular dynamics simulation. The Prime module was utilised to perform post-MM/GBSA analysis on these three molecules along with the toxicity profiling using Protox II web server. This study suggests that dostinex, formoterol, and raloxifene may act as effective inhibitors of the TyS receptor which could be used as novel antileishmanial agents for the therapeutic applications. Thorough preclinical studies are necessary to confirm the identified compounds chemotherapeutic qualities.

Influence of chlorpyrifos and endosulfan and their metabolites on the virulence of Helicobacter pylori.

Organochlorine (OC) and organophosphorus (OP) pesticides such as chlorpyrifos (CPF) and endosulfan (ES) have been associated with a plethora of adverse health effects. Helicobacter pylori (H. pylori) infection can lead to gastrointestinal diseases by regulating several cellular processes. Thus, the current study focuses on the effect of the co-exposure to pesticides and H. pylori on gastric epithelial cells. We have used the in-silico approach to determine the interactive potential of pesticides and their metabolites with H. pylori-associated proteins. Further, various in-vitro methods depict the potential of ES in enhancing the virulence of H. pylori. Our results showed that ES along with H. pylori affects the mitochondrial dynamics, increases the transcript expression of mitochondrial fission genes, and lowers the mitochondrial membrane potential and biomass. They also promote inflammation and lower oxidative stress as predicted by ROS levels. Furthermore, co-exposure induces the multi-nucleated cells in gastric epithelial cells. In addition, ES along with H. pylori infection follows the extrinsic pathway for apoptotic signaling. H. pylori leads to the NF-κB activation which in turn advances the ß-catenin expression. The expression was further enhanced in the co-exposure condition and even more prominent in co-exposure with ES-conditioned media. Thus, our study demonstrated that pesticide and their metabolites enhance the pathogenicity of H. pylori infection.

Epidrugs: alternative chemotherapy targeting Theileria annulata schizont stage parasites.

The growing emergence of resistance to current anti-theilerial agents necessitates the exploration of alternative approaches to drug discovery. This study evaluated the antiparasitic efficacy of 148 compounds derived from an epigenetic inhibitor library against the schizont stage of a Theileria annulata-infected cell line. Initial screening at a concentration of 10 µM identified 27 compounds exhibiting promising anti-theilerial activity. Further investigation, including determination of the 50% inhibitory concentration (IC50) and host cell cytotoxicity assay, highlighted seven highly effective compounds (SAHA, BVT-948, Trichostatin A, Methylstat, Plumbagin, Ryuvidine, and TCE-5003) against T. annulata-infected cells. Analysis of the active compounds revealed their inhibitory action against various human targets, such as HDAC (SAHA and Trichostatin A), SET domain (Ryuvidine), PRMT (BVT-948 and TCE-5003), histone demethylase (Methylstat), and ROS/apoptosis inducer (Plumbagin). We identified gene orthologs of these targets in Theileria and conducted molecular docking studies, demonstrating effective binding of the compounds with their respective targets in the parasite, supported by in vitro data. Additionally, we performed in silico ADME/T predictions, which indicated potential mutagenic and hepatotoxic effects of Plumbagin, Methylstat, and TCE-5003, rendering them unsuitable for drug development. Conversely, SAHA, Trichostatin A, and BVT-948 showed promising characteristics and may represent potential candidates for future development as chemotherapeutic agents against tropical theileriosis. These findings provide valuable insights into the search for novel anti-theilerial drugs and offer a basis for further research in this area.IMPORTANCETheileria annulata is a protozoan parasite responsible for tropical theileriosis, a devastating disease affecting cattle. Traditional chemotherapy has limitations, and the study explores the potential of epidrugs as an alternative treatment approach. Epidrugs are compounds that modify gene expression without altering the underlying DNA sequence, offering a novel way to combat parasitic infections. This research is pivotal as it addresses the urgent need for innovative therapies against T. annulata, contributing to the development of more effective and targeted treatments for infected livestock. Successful implementation of epidrugs could not only enhance the well-being of cattle but also have broader implications for the control of parasitic diseases, showcasing the paper's significance in advancing veterinary science and improving livestock health globally.

Manifesting the Dasatinib-gallic acid co-amorphous system to augment anticancer potential: Physicochemical characterization, in silico molecular simulation, ex vivo permeability, and in vitro efficacy.

Dasatinib (DAB) has been explored for repurposing in the treatment of breast cancer (BC) due to its known effectiveness in treating leukemia, in addition to its role as a tyrosine kinase inhibitor. Gallic acid (GA) was chosen as a co-former due to its anticancer potential in BC, as demonstrated in several previous studies. DAB is a low-solubility drug, which is a significant hurdle for its oral bioavailability. To address this limitation, a DAB and GA co-amorphous (DAB-GA-CA) system was developed using liquid-assisted grinding and ball mill technology to enhance solubility, bioavailability, and anti-tumor efficacy. Physical characterization investigation revealed that the emergence of the halo diffractogram in PXRD, single glass transition temperature (Tg) value at 111.7 °C in DSC thermogram, and irregularly shaped blocks with loose, porous surfaces in SEM analysis indicated the formation of the DAB-GA-CA system at 1:1 M ratio. Furthermore, FTIR, Raman spectroscopy, in-silico molecular docking, and molecular dynamic studies confirmed the intermolecular hydrogen connections between DAB and GA. Moreover, the outcomes of the ligands (DAB and GA) and receptors (BCL-2, mTOR, estrogen receptor, and HER-2) docking studies demonstrated that both DAB and GA could interact with those receptors, leading to preventive action on BC cells. Additionally, the solubility and dissolution rate significantly improved at pH 6.8, and the permeability study indicated that DAB-GA-CA showed 1.9 times higher apparent permeability compared to crystalline DAB. Furthermore, in vitro cytotoxicity assessments of the DAB-GA-CA system revealed 3.42 times lower IC50 than free DAB. The mitochondrial membrane depolarization, apoptotic index, and reactive oxygen species formation in MCF-7 cells were also notably higher in the DAB-GA-CA system than in free DAB. Hence, this research suggests that the DAB-GA-CA system could substantially enhance oral delivery, solubility, and therapeutic efficacy.

Enhancing breast cancer treatment: Comprehensive study of gefitinib-loaded poloxamer 407/TPGS mixed micelles through design, development, in-silico modelling, In-Vitro testing, and Ex-Vivo characterization.

Breast cancer continues to pose a substantial global health challenge, emphasizing the critical need for the advancement of novel therapeutic approaches. Key players in the regulation of apoptosis, a fundamental process in cell death, are the B-cell lymphoma 2 (Bcl-2) family proteins, namely Bcl-2 and Bax. These proteins have garnered attention as highly promising targets for the treatment of breast cancer. Targeting the overexpressed anti-apoptotic Bcl-2 protein in breast cancer, Gefitinib (GEF), an EGFR (Epidermal Growth Factor Receptor) inhibitor, emerges as a potential solution. This study focuses on designing Gefitinib-loaded polymeric mixed micelles (GPMM) using poloxamer 407 and TPGS (D-alpha tocopherol PEG1000 succinate) for breast cancer therapy. In silico analyses unveil strong interactions between GEF- Bcl-2 and TPGS-Pgp-2 receptors, indicating efficacy against breast cancer. Molecular dynamics simulations offer insights into GEF and TPGS interactions within the micelles. Formulation optimization via Design of Experiment ensures particle size and entrapment efficiency within acceptable ranges. Characterization tools such as zeta sizer, ATR-FTIR, XRD, TEM, AFM, NMR, TGA, and DSC confirms particle size, structure, functional groups, and thermodynamic events. The optimized micelles exhibit a particle size of 22.34 ± 0.18 nm, PDI of 0.038 ± 0.009, and zeta potential of -0.772 ± 0.12 mV. HPLC determines 95.67 ± 0.34% entrapment efficiency and 1.05 ± 0.12% drug loading capacity. In-vitro studies with MDA-MB-231 cell lines demonstrate enhanced cytotoxicity of GPMM compared to free GEF, suggesting its potential in breast cancer therapy. Cell cycle analysis reveals apoptosis induction through key apoptotic proteins. Western blot results confirm GPMM's ability to trigger apoptosis in MDA-MB-231 cells by activating caspase-3, Bax, Bcl-2, and Parp. In conclusion, these polymeric mixed micelles show promise in selectively targeting cancer cells, warranting future in-vivo studies for optimized clinical application against breast cancer.

Development of venetoclax with 2-hydroxypropyl-beta-cyclodextrin inclusion complex for improved bioavailability.

Cyclodextrin complexes loaded with venetoclax for improved solubility and therapeutic efficacy as repurposed drug. The venetoclax-cyclodextrin inclusion complex was prepared using kneading method. Primarily in-silico molecular docking study was performed to examine the possible interaction between venetoclax and hydroxypropyl-ß-cyclodextrin (HP-ß-CD) and extensively characterized. The in-vitro studies were performed using A-549 lung epithelial cancer cells. The in-vivo pharmaco-kinetic studies was performed on wistar rats. The aqueous solubility of venetoclax was increased upto 3.16 folds, as compared with pure venetoclax with entrapment efficiency (EE%) was determined 95.44 ± 0.3%. In-vitro cytotoxicity studies were carried on A-549 lung epithelial cancer cells, wherein BCL-2 receptors were highly over-expressed and IC 50 values for venetoclax and venetoclax- HP-ß-CD complex was calculated at 24 and 48 hrs in the order of 1.241 µg/ml, 0.68 µg/ml and 0.757719 µg/ml, 0.6125 µg/mL, respectively. The oral bioavailability was increased 4.03 times compared to the pure drug. The venetoclax-HP-ß-CD inclusion complexes showed the increased aqueous solubility with improved anticancer activities.Communicated by Ramaswamy H. Sarma.

Development of naphthalimide hydrazide derivatives as potent antibacterial agents against carbapenem-resistant A. baumannii.

In this work, a novel series of naphthalimide hydrazide derivatives were designed, synthesized and evaluated against a bacterial pathogen panel. Most of the compounds were found to exhibit potent antibacterial activity against carbapenem-resistant A. baumannii BAA 1605, with MIC ranging from 0.5 to 16 µg mL-1. Compounds 5b, 5c, 5d and 5e showed the most potent antibacterial activity, with an MIC range of 0.5-1 µg mL-1. These compounds were also found to be non-toxic to Vero cells with a high selectivity index. Further, they were active against 24 clinical isolates of MDR-AB with potent antibacterial activity. In addition, synergistic studies revealed that compound 5d exhibited synergism with FDA-approved drugs, as further validated through time-kill kinetic studies. These results highlight the potential of the synthesized compounds as promising leads for the development of novel and selective agents against carbapenem-resistant A. baumannii.

Increased parasite surface antigen-2 expression in clinical isolates of Leishmania donovani augments antimony resistance.

Resistance to sodium antimony gluconate (SAG) is a major cause of therapeutic failure in a large proportion of visceral leishmaniasis (VL) cases. Determinants of SAG resistance have been widely studied; however, the mechanism operating in clinical isolates is poorly understood. In the present study, expression of parasite surface antigen-2 (PSA-2) gene was studied in clinical isolates of Leishmania donovani comprising of antimony resistant (n=10) and sensitive (n=4) parasites. The expression of PSA-2 gene was found to be consistently high in SAG resistant clinical isolates (≥1.5-fold) at both transcript and protein level. Further, over-expression of PSA-2 in L. donovani isolates (LdPSA-2(++)) resulted in conversion of SAG sensitive phenotype to resistant. The LdPSA-2(++) parasites showed significantly decreased susceptibility towards SAG (>12-fold), amphotericin B (>4-fold) and miltefosine (>2.5-fold). Marked decrease in antimony accumulation and enhanced tolerance towards complement mediated lysis was evident in LdPSA-2(++) parasites. The study established the role of PSA-2 gene in SAG resistance and its potential as a biomarker to distinguish resistant and sensitive clinical isolates of L. donovani.

Reliable diagnosis of post-kala-azar dermal leishmaniasis (PKDL) using slit aspirate specimen to avoid invasive sampling procedures.

OBJECTIVE: Confirmatory diagnosis of post-kala-azar dermal leishmaniasis (PKDL) is primarily based on invasive skin biopsy procedure. We evaluated the utility of minimally invasive slit aspirate specimen for serological and molecular diagnosis of PKDL. We compared the PKDL diagnosis using slit aspirate and skin biopsy specimens from the same patients. METHODS: Serological diagnosis using rK39 strip test was performed with serum and slit aspirate sample; molecular diagnosis for parasite detection and quantification was carried out by quantitative real-time PCR (Q-PCR) with skin biopsy and slit aspirate sample. RESULTS: The rK39 serological strip test was positive in all PKDL cases with both slit aspirate and serum samples (n = 50) and negative in all control cases (n = 24), giving a sensitivity of 100% (95% CI: 92.9-100%) and a specificity of 100% (95% CI: 86.2-100%). Quantitative-PCR detected parasite in all PKDL slit aspirates (n = 50, sensitivity = 100%, 95% CI: 92.9-100%) and tissue biopsies (n = 46, sensitivity = 100%, 95% CI: 92.3-100; it was negative in all controls including dermal tissues (n = 24) and slit aspirates (n = 24), giving specificity of 100% (95% CI: 86.2-100%). The parasite load in tissue and slit aspirate samples was significantly (P < 0.0001) correlated (r = 0.82). CONCLUSIONS: Slit aspirates are a simpler and minimally invasive sampling technique for initial screening by serology followed by confirmatory diagnosis of PKDL with microscopy and/or Q-PCR. The simplified procedure has the potential for epidemiological studies and assessment of cure in PKDL.

Validation of a simple resazurin-based promastigote assay for the routine monitoring of miltefosine susceptibility in clinical isolates of Leishmania donovani.

Simple, cost-effective approach for routine surveillance of parasite susceptibility to antileishmanial drug miltefosine (MIL) is highly desirable for controlling emergence of drug resistance in visceral leishmaniasis (VL). We validated a simple resazurin-based fluorimetric assay using promastigotes to track natural MIL tolerance in Leishmania donovani parasites from VL cases (n = 17) against standard amastigote assay, in two different labs in India. The inter-stage MIL susceptibility correlated strongly (r = 0.70, p = 0.0018) using J774.A.1 macrophage cell line-based amastigote assay and fluorescence-based resazurin assay for promastigotes. Investigation of inter-stage MIL susceptibility for the same set of clinical isolates in another lab also showed a strong correlation (r = 0.72, p = 0.0012) using mouse peritoneal macrophages for amastigote assay and resazurin-based alamar blue assay for promastigotes. Additionally, parasites from post-kala-azar dermal leishmaniasis (PKDL) lesions (n = 7, r = 0.78, p = 0.046) and MIL-induced parasites (r = 0.92, p = 0.0001; n = 3) also exhibited a strongly correlated inter-stage miltefosine susceptibility. Thus, our results support the utility of resazurin assay as a simplified biological tool for MIL susceptibility monitoring in clinical isolates from MIL-treated VL/PKDL patients.

The glycoprotein gp63- a potential pan drug target for developing new antileishmanial agents.

Leishmaniasis is a tropical parasitic disease caused by Leishmania spp. They cause several presentations of illness ranging from cutaneous leishmaniasis to visceral leishmaniasis. The current arsenal of drugs to treat leishmaniasis is limited, and drug resistance further impedes the problem. Therefore, it is necessary to revisit the available information to identify an alternative or new target for treatment. The glycoprotein 63 (gp63), is a potential anti-leishmanial target that plays a significant role in host-pathogen interaction and virulence. Many studies are ongoing to develop gp63 inhibitors or use it as a vaccine target. In this review, we will discuss the potential of gp63 as a drug target. This review summarises the studies focusing on gp63 as a drug target and its inhibitors identified using in silico approaches.

Homology modeling, virtual screening, molecular docking, and dynamics studies for discovering Staphylococcus epidermidis FtsZ inhibitors.

Staphylococcus epidermidis is the most common cause of medical device-associated infections and is an opportunistic biofilm former. Among hospitalized patients, S. epidermidis infections are the most prevalent, and resistant to most antibiotics. In order to overcome this resistance, it is imperative to treat the infection at a cellular level. The present study aims to identify inhibitors of the prokaryotic cell division protein FtsZ a widely conserved component of bacterial cytokinesis. Two substrate binding sites are present on the FtsZ protein; the nucleotide-binding domain and the inter-domain binding sites. Molecular modeling was used to identify potential inhibitors against the binding sites of the FtsZ protein. One hundred thirty-eight chemical entities were virtually screened for the binding sites and revealed ten molecules, each with good binding affinities (docking score range -9.549 to -4.290 kcal/mol) compared to the reference control drug, i.e., Dacomitinib (-4.450 kcal/mol) and PC190723 (-4.694 kcal/mol) at nucleotide and inter-domain binding sites respectively. These top 10 hits were further analyzed for their ADMET properties and molecular dynamics simulations. The Chloro-derivative of GTP, naphthalene-1,3-diyl bis(3,4,5-trihydroxybenzoate), Guanosine triphosphate (GTP), morpholine and methylpiperazine derivative of GTP were identified as the lead molecules for nucleotide binding site whereas for inter-domain binding site, 1-(((amino(iminio)methyl)amino)methyl)-3-(3-(tert-butyl)phenyl)-6,7-dimethoxyisoquinolin-2-ium, and Chlorogenic acidwere identified as lead molecules. Molecular dynamics simulation and post MM/GBSA analysis of the complexes revealed good protein-ligand stability predicting them as potential inhibitors of FtsZ (Figure 1). Thus, identified FtsZ inhibitors are a promising lead compounds for S. epidermidis related infections.

In-silico investigation of E8 surface protein of the monkeypox virus to identify potential therapeutic agents.

The re-emergence of the monkeypox virus (MPXV) in 2022 has become a global issue. The virus was first found in Denmark in 1958. The first human MPXV disease was reported in 1980 in Congo, caused by a rare zoonotic virus belonging to the genus Orthopoxvirus and the family Poxviridae. Like SARS-CoV, there are no specific drugs to treat this infection. Taking cues from the successful implementation of drug repositioning for the Covid-19 pandemic using in silico drug discovery. We employed structure-based drug design in the study to repurpose the existing drug and natural product derivatives libraries against MPXV. The E8 protein was chosen as a therapeutic target because it is a surface membrane protein involved in viral entry and adhesion to the host cell surface membrane. Our study was bifurcated into the following steps; determining and analyzing the structure of the E8, followed by structure-based virtual screening of different datasets (natural products obtained from bacteria and fungi and FDA-approved drugs) to identify the hits. Based on the best binding affinities and protein-ligand interactions, we further proceeded for molecular dynamic (MD) studies of the identified hits, which revealed Gabosine D (docking score = -8.469 kcal/mol, MM/GBSA dG bind = -41.6729 kcal/mol) and Edoxudine (docking score = -6.372 kcal/mol, MM/GBSA dG bind = -35.8291 kcal/mol) as the best lead molecules. MD simulation for 100 ns was performed in triplicate, and post MM/GBSA analysis was conducted, which proves the stability of the identified leads. In addition, their ADME profiles also confirmed their suitability as therapeutic options for the treatment of monkeypox.Communicated by Ramaswamy H. Sarma.

Molecular docking and molecular dynamics studies of natural products unravel potential inhibitors against OmpA of Acinetobacter baumannii.

Emerging antimicrobial resistance has highlighted the need to design more effective antibiotics to treat deadly bacterial infections. Acinetobacter baumannii's outer membrane protein A (OmpA) is a critical virulence component involved in biofilm formation, immunomodulation, and antibiotic resistance, which characterizes it as a potential therapeutic target. The present study aimed to screen the natural product database (>1,00,000) to identify the potential inhibitor against OmpA. Molecular docking studies revealed that 10 compounds had good docking scores (≤ -7 kcal/mol) compared to the reported inhibitor epiestriol (-3.079). Further, these 10 compounds were subjected to ADME analysis and MMGBSA analysis. Based on MMGBSA results, we selected 5 compounds [NP-1 (MolPort-039-337-117), NP-5(MolPort-019-932-973), NP-6 (MolPort-005-948-336), NP-8(MolPort-042-673-978) and NP-9(MolPort-042-673-766)] with high binding affinity. Molecular dynamics simulation found that NP-5, NP-8, and NP-9 were stable after analysing their RMSD, RMSF, the radius of gyration, and hydrogen interactions of complexes. Our study revealed that NP-5, NP-8, and NP-9 bind perfectly with OmpA and can act as its potential inhibitors. The results of this study imply that the identified inhibitors have the potential for further investigation.Communicated by Ramaswamy H. Sarma.