Identification of two natural compound inhibitors of Leishmania donovani Spermidine Synthase (SpdS) through molecular docking and dynamic studies

Unveiling of the antileishmanial activities of Linalool loaded zinc oxide nanocomposite through its potent antioxidant and immunomodulatory effects

This study aimed to produce linalool loaded zinc oxide nanocomposite (LZNPs) and assess its in vitro and in vivo antileishmanial effects against Leishmania major. LZNPs was produced through the synthesis of an ethanolic solution containing polyvinyl alcohol. The average size of LZNPs was determined to be 105 nm. The findings indicated that LZNPs displayed significant (p < 0.01) antileishmanial effects on promastigotes and amastigotes. Following exposure of promastigotes to LZNPs, there was a notable rise in the percentage of early and late apoptotic cells from 9.0 to 57.2 %. The gene expression levels of iNOS, IFN-γ, and TNF-α in macrophages were upregulated in a dose-dependent approach following exposure to LZNPs. LZNPs alone and in conjunction with glucantime (Glu) resulted in a reduction in the diameter and parasite load of CL lesions in infected mice. Treatment of the CL-infected mice with LZNPs at 25 and 50 mg/kg mainly in combination with Glu-reduced the tissue level of malondialdehyde (MDA), increased both gene and protein expression of the antioxidant enzymes as well as raised the expression level of IFN-γ and IL-12 cytokines, whereas caused a significant reduction in the expression level of IL-4. The present study shows that LZNPs has potent antileishmanial effects and controls CL in a mice model through its antioxidant and immunomodulatory properties. Further investigation, especially in clinical trials, could explore the potential use of this nanocomposite in managing and treating CL.

The Application of MD Simulation to Lead Identification, Vaccine Design, and Structural Studies in Combat against Leishmaniasis - A Review

Drug discovery, vaccine design, and protein interaction studies are rapidly moving toward the routine use of molecular dynamics simulations (MDS) and related methods. As a result of MDS, it is possible to gain insights into the dynamics and function of identified drug targets, antibody-antigen interactions, potential vaccine candidates, intrinsically disordered proteins, and essential proteins. The MDS appears to be used in all possible ways in combating diseases such as cancer, however, it has not been well documented as to how effectively it is applied to infectious diseases such as Leishmaniasis. As a result, this review aims to survey the application of MDS in combating leishmaniasis. We have systematically collected articles that illustrate the implementation of MDS in drug discovery, vaccine development, and structural studies related to Leishmaniasis. Of all the articles reviewed, we identified that only a limited number of studies focused on the development of vaccines against Leishmaniasis through MDS. Also, the PCA and FEL studies were not carried out in most of the studies. These two were globally accepted utilities to understand the conformational changes and hence it is recommended that this analysis should be taken up in similar approaches in the future.

In Silico Exploration of the Trypanothione Reductase (TryR) of L. mexicana

Human leishmaniasis is a neglected tropical disease which affects nearly 1.5 million people every year, with Mexico being an important endemic region. One of the major defense mechanisms of these parasites is based in the polyamine metabolic pathway, as it provides the necessary compounds for its survival. Among the enzymes in this route, trypanothione reductase (TryR), an oxidoreductase enzyme, is crucial for the Leishmania genus' survival against oxidative stress. Thus, it poses as an attractive drug target, yet due to the size and features of its catalytic pocket, modeling techniques such as molecular docking focusing on that region is not convenient. Herein, we present a computational study using several structure-based approaches to assess the druggability of TryR from L. mexicana, the predominant Leishmania species in Mexico, beyond its catalytic site. Using this consensus methodology, three relevant pockets were found, of which the one we call σ-site promises to be the most favorable one. These findings may help the design of new drugs of trypanothione-related diseases.

Molecular Docking and Molecular Dynamics Simulations in Related to Leishmania donovani: An Update and Literature Review

Leishmaniasis, a disease caused by Leishmania parasites and transmitted via sandflies, presents in two main forms: cutaneous and visceral, the latter being more severe. With 0.7 to 1 million new cases each year, primarily in Brazil, diagnosing remains challenging due to diverse disease manifestations. Traditionally, the identification of Leishmania species is inferred from clinical and epidemiological data. Advances in disease management depend on technological progress and the improvement of parasite identification programs. Current treatments, despite the high incidence, show limited efficacy due to factors like cost, toxicity, and lengthy regimens causing poor adherence and resistance development. Diagnostic techniques have improved but a significant gap remains between scientific progress and application in endemic areas. Complete genomic sequence knowledge of Leishmania allows for the identification of therapeutic targets. With the aid of computational tools, testing, searching, and detecting affinity in molecular docking are optimized, and strategies that assess advantages among different options are developed. The review focuses on the use of molecular docking and molecular dynamics (MD) simulation for drug development. It also discusses the limitations and advancements of current treatments, emphasizing the importance of new techniques in improving disease management.

Novel chemical scaffold as potential drug against Leishmania donovani: Integrated computational and experimental approaches

In this study, we have screened a large number of Food and Drug Administration-approved compounds for novel anti-leishmanial molecules targeting the citrate synthase enzyme of the parasite. Based on their docking and molecular dynamic simulation statistics, five compounds were selected. These compounds followed Lipinski's rule of five. Additionally, in vitro, antileishmanial and cytotoxicity studies were performed. The three compounds, Abemaciclib, Bazedoxifene, and Vorapaxar, had shown effective anti-leishmanial activities with IC50 values of 0.92 ± 0.02, 0.65 ± 0.09, and 6.1 ± 0.91 against Leishmania donovani promastigote and with EC50 values of 1.52 ± 0.37, 2.11 ± 0.38, 10.4 ± 1.27 against intramacrophagic amastigote without significantly harming macrophage cells. Among them, from in silico and antileishmanial activities studies, Abemaciclib had been selected based on their less binding energy, good antileishmanial activities, and also a significant difference in their binding energy with human citrate synthase for cell death mechanistic studies using flow cytometry and a DNA fragmentation assay. The action of this compound resulted in an increased reactive oxygen species production, depolarization of mitochondrial membrane potential, DNA damage, and an increase in the sub-G1 cell population. These properties are the hallmarks of apoptosis which were further confirmed by apoptotic assay. Based on the above result, this anticancer compound Abemaciclib could be employed as a potential treatment option for leishmaniasis after further confirmation.

Molecular-level strategic goals and repressors in Leishmaniasis - Integrated data to accelerate target-based heterocyclic scaffolds

Leishmaniasis is a complex of neglected tropical diseases caused by various species of leishmanial parasites that primarily affect the world's poorest people. A limited number of standard medications are available for this disease that has been used for several decades, these drugs have many drawbacks such as resistance, higher cost, and patient compliance, making it difficult to reach the poor. The search for novel chemical entities to treat leishmaniasis has led to target-based scaffold research. Among several identified potential molecular targets, enzymes involved in the purine salvage pathway include polyamine biosynthetic process, such as arginase, ornithine decarboxylase, S-adenosylmethionine decarboxylase, spermidine synthase, trypanothione reductase as well as enzymes in the DNA cell cycle, such as DNA topoisomerases I and II plays vital role in the life cycle survival of leishmanial parasite. This review mainly focuses on various heterocyclic scaffolds, and their specific inhibitory targets against leishmaniasis, particularly those from the polyamine biosynthesis pathway and DNA topoisomerases with estimated activity studies of various heterocyclic analogs in terms of their IC₅₀ or EC₅₀ value, reported molecular docking analysis from available published literatures.

Unique thiol metabolism in trypanosomatids: Redox homeostasis and drug resistance

Trypanosomatids are mainly responsible for heterogeneous parasitic diseases: Leishmaniasis, Sleeping sickness, and Chagas disease and control of these diseases implicates serious challenges due to the emergence of drug resistance. Redox-active biomolecules are the endogenous substances in organisms, which play important role in the regulation of redox homeostasis. The redox-active substances like glutathione, trypanothione, cysteine, cysteine persulfides, etc., and other inorganic intermediates (hydrogen peroxide, nitric oxide) are very useful as defence mechanism. In the present review, the suitability of trypanothione and other essential thiol molecules of trypanosomatids as drug targets are described in Leishmania and Trypanosoma. We have explored the role of tryparedoxin, tryparedoxin peroxidase, ascorbate peroxidase, superoxide dismutase, and glutaredoxins in the anti-oxidant mechanism and drug resistance. Up-regulation of some proteins in trypanothione metabolism helps the parasites in survival against drug pressure (sodium stibogluconate, Amphotericin B, etc.) and oxidative stress. These molecules accept electrons from the reduced trypanothione and donate their electrons to other proteins, and these proteins reduce toxic molecules, neutralize reactive oxygen, or nitrogen species; and help parasites to cope with oxidative stress. Thus, a better understanding of the role of these molecules in drug resistance and redox homeostasis will help to target metabolic pathway proteins to combat Leishmaniasis and trypanosomiases.

The effect of putrescine on the lysozyme activity and structure: Spectroscopic approaches and molecular dynamic simulation

The present research addressed the influence of polyamine (putrescine) on the compound as well as function of lysozyme; accordingly, UV- Visible, fluorescence spectroscopy and simulation method were applied to fulfill this goal. Lysozyme's structural variability was examined at various putrescine ‌concentrations; also, the putrescine binding to lysozyme was addressed using spectrofluorescence, circular dichroism (CD) and UV-Vis measurements. The obtained results indicated that with raising the putrescine concentration, the intrinsic quenching fluorescence of lysozyme was decreased based on the static mechanism. Analysis of thermodynamic parameters also indicated that van der Waals as well as hydrogen bond forces served a fundamental role in determining the resulting stability; this was in agreement with modeling studies. Measurement of UV absorption spectroscopy, fluorescence spectroscopy, and circular dichroism spectroscopy also demonstrated that lysozyme's second and tertiary structures were altered in a putrescine concentration-dependent manner. Putrescine inhibited lysozyme's enzymatic activity, displaying its affinity with the lysozyme's active site. Further, molecular simulation conducted revealed that putrescine could have spontaneous binding to lysozyme, changing its structure, thus further emphasizing the experimental results.

Evaluation of the In Vitro Antiparasitic Effect of the Essential Oil of Cymbopogon winterianus and Its Chemical Composition Analysis

Cymbopogon winterianus, known as “citronella grass”, is an important aromatic and medicinal tropical herbaceous plant. The essential oil of C. winterianus (EOCw) is popularly used to play an important role in improving human health due to its potential as a bioactive component. The present study aimed to identify the components of the essential oil of C. winterianus and verify its leishmanicidal and trypanocidal potential, as well as the cytotoxicity in mammalian cells, in vitro. The EOCw had geraniol (42.13%), citronellal (17.31%), and citronellol (16.91%) as major constituents. The essential oil only exhibited significant cytotoxicity in mammalian fibroblasts at concentrations greater than 250 μg/mL, while regarding antipromastigote and antiepimastigote activities, they presented values considered clinically relevant, since both had LC50 < 62.5 μg/mL. It can be concluded that this is a pioneer study on the potential of the essential oil of C. winterianus and its use against the parasites T. cruzi and L. brasiliensis, and its importance is also based on this fact. Additionally, according to the results, C. winterianus was effective in presenting values of clinical relevance and low toxicity and, therefore, an indicator of popular use.

Polyamine Metabolism in Leishmania Parasites: A Promising Therapeutic Target

Parasites of the genus Leishmania cause a variety of devastating and often fatal diseases in humans and domestic animals worldwide. The need for new therapeutic strategies is urgent because no vaccine is available, and treatment options are limited due to a lack of specificity and the emergence of drug resistance. Polyamines are metabolites that play a central role in rapidly proliferating cells, and recent studies have highlighted their critical nature in Leishmania. Numerous studies using a variety of inhibitors as well as gene deletion mutants have elucidated the pathway and routes of transport, revealing unique aspects of polyamine metabolism in Leishmania parasites. These studies have also shed light on the significance of polyamines for parasite proliferation, infectivity, and host-parasite interactions. This comprehensive review article focuses on the main polyamine biosynthetic enzymes: ornithine decarboxylase, S-adenosylmethionine decarboxylase, and spermidine synthase, and it emphasizes recent discoveries that advance these enzymes as potential therapeutic targets against Leishmania parasites.