anti-Leishmania Agents Research Articles

In vitro assessment of Dracocephalum lindbergii for growth inhibition, apoptosis induction, and cytokine modulation against Leishmaniamajor

Leishmaniasis is a vector-borne disease caused by several species of flagellate protozoan parasites belonging to the genus Leishmania, which are part of the Trypanosomatidae family. This study aims to evaluate the in vitro anti-Leishmania activity of Dracocephalum lindbergii Rech.f (D. lindbergii) on the growth, apoptosis induction, and proliferation of Leishmania major. To conduct this study, the aerial parts of D. lindbergii were collected during the flowering stage in May 2022 from North Khorasan province, Iran. The plant material was extracted using various solvents, starting with those of lower polarity and progressing to those of higher polarity. To assess the impact of the D. lindbergii fraction on L. major promastigotes, amastigotes, and macrophages (THP-1), cell viability was determined using the MTT assay. Additionally, flow cytometry with the Annexin V-PE apoptosis detection kit was employed to distinguish between viable, necrotic, and apoptotic promastigotes in response to treatment with the 100 % methanolic fraction of D. lindbergii (D). The expression levels of TNF-α, IFN-γ, IL-12, IL-10, TGF-β, IL4, iNOS, and GAPDH were quantified using real-time PCR (qPCR) on the macrophage cell line. Each treatment approach exhibited marked anti-leishmanial effects across different concentrations over 24, 48, and 72 h of incubation, showing statistically significant differences compared to the untreated control group (P < 0.001). Different concentrations of D, MAT, and AmpB, both individually and in combination, significantly reduced the total number of intramacrophage amastigotes compared to the untreated control groups at 24, 48, and 72 h. The results also showed time-dependent variations in the anti-Leishmania activity of the fraction. In terms of cellular morphology, treated cells exhibited changes such as shrinkage, cytoplasmic condensation, and reduced mobility, particularly noticeable after 24 h of treatment. Additionally, fraction D demonstrated significant antioxidant properties. This study highlights the potential of D. lindbergii as an anti-Leishmania agent, with the 100 % methanolic fraction emerging as a promising candidate for the development of novel treatments for leishmaniasis.

Anti-Leishmania amazonensis Activity of Morolic Acid, a Pentacyclic Triterpene with Effects on Innate Immune Response during Macrophage Infection.

Leishmaniasis is a group of infectious diseases transmitted to humans during vector bites and caused by protozoans of the genus Leishmania. Conventional therapies face challenges due to their serious side effects, prompting research into new anti-leishmania agents. In this context, we investigated the effectiveness of morolic acid, a pentacyclic triterpene, on L. amazonensis promastigotes and amastigotes. The present study employed the MTT assay, cytokine analysis using optEIATM kits, an H2DCFDA test, and nitric oxide dosage involving nitrite production and Griess reagent. Morolic acid inhibited promastigote and axenic amastigote growth forms at IC50 values of 1.13 µM and 2.74 µM, respectively. For cytotoxicity to macrophages and VERO cells, morolic acid obtained respective CC50 values of 68.61 µM and 82.94 µM. The compound causes damage to the parasite membrane, leading to cellular leakage. In the infection assay, there was a decrease in parasite load, resulting in a CI50 of 2.56 µM. This effect was associated with immunomodulatory activity, altering macrophage structural and cellular parasite elimination mechanisms. Morolic acid proved to be an effective and selective natural compound, making it a strong candidate for future in vivo studies in cutaneous leishmaniasis.

Antiprotozoal potential of Vismia species (Hypericaceae), medicinal plants used to fight cutaneous leishmaniasis

Ethnopharmacological relevanceSpecies of Vismia (Hypericaceae), known in Brazil as “lacre”, are commonly used in traditional Amazonian medicine for the treatment of skin lesions, including those caused by Leishmania infection. Aim of the studyHexane extracts from the leaves of Vismia cayennensis, V. gracilis, V. sandwithii and V. guianensis, as well as from the fruits of the latter, in addition to the anthraquinones vismiaquinone, physcion and chrysophanol isolated from these species were explored for their anti-promastigote and anti-amastigote activity on Leishmania amazonensis. Materials and methodsExtracts were prepared by static maceration with n-hexane. The compounds, isolated by chromatographic techniques, were identified by spectroscopic methods (1H and 13C NMR). Promastigotes of L.amazonensis were incubated with hexane extracts (1–50 μg/mL) or anthraquinones (1–50 μM) and the parasite survival analyzed. The action of compounds on reactive oxygen species (ROS) production, mitochondrial membrane potential, and membrane integrity of promastigotes were evaluated by flow cytometer, and the cytotoxicity on mammalian cells using MTT assay. Furthermore, the activity of compounds against amastigotes and nitric oxide production were also investigated. ResultsVismiaquinone and physcion were obtained from the leaves of V. guianensis. Physcion, as well as chrysophanol, were isolated from V. sandwithii. Vismia cayennensis and V. gracilis also showed vismiaquinone, compound detected in lower quantity in the fruits of V. guianensis. All extracts were active against the parasite, corroborating the popular use. The greatest activity against promastigotes was achieved with V. guianensis extract (IC50 4.3 μg/mL), precisely the most used Vismia species for treating cutaneous leishmaniasis. Vismiaquinone and physcion exhibited relevant activity with IC50 12.6 and 2.6 μM, respectively. Moreover, all extracts and anthraquinones tested induced ROS production, mitochondrial dysfunction, membrane disruption and were able to kill intracellular amastigote forms, being worthy of further in vivo studies as potential antileishmanial drugs. ConclusionsThe overall data achieved in the current investigation scientifically validate the traditional use of Vismia species, mainly V. guianensis, as an anti-Leishmania agent. Furthermore, the promising results presented here indicate species of Vismia as potentially useful resources of Brazilian flora for the discovery of therapeutic solutions for neglected diseases.

Investigation of the Structural and Electronic Properties of the Novel Synthesized Methyl 2-(2-oxo-2H-chromen-4-ylamino) benzoate Compound by DFT Method and Evaluation of its Anti-Leishmania Agent Potential by Molecular Docking Study

Leishmaniasis is a disease caused by different species of the leishmania parasite, transmitted through the sandfly, within the group of protozoa. According to the World Health Organization, leishmaniasis is one of the most encountered seven tropical diseases. Trypanothione reductase is a vital enzyme for the parasite. This has made Trypanothione reductase a potential target in the treatment of leishmaniasis. The limitations of current therapeutic options and the high cost have increased the motivation for research on the inhibition of Trypanothione reductase. In this study, the structural and electronic properties of the newly synthesized compound methyl 2-(2-oxo-2H-chromen-4-ylamino) benzoate were calculated using DFT/B3LYP and 6-311++G(d,p) basis set. The calculated structural parameters were found to be highly compatible when compared with experimental studies. The crystal packing of the compound was examined through the Hirshfeld surface analysis method. When the potential of the compound to be used as a drug was evaluated using Lipinski criteria, no hindrance to its use in living organisms was found. As the crystal structure of the enzyme was unknown, homology modeling was performed. Finally, in the molecular docking study, the interaction mechanisms of the compound mentioned in the title and the compound clomipramine used as a control in the receptor's active site were examined. The results revealed that the compound mentioned in the title demonstrated a better potential compared to the control compound.

Approved drugs successfully repurposed against Leishmania based on machine learning predictions.

Drug repurposing is a promising approach towards the discovery of novel treatments against Neglected Tropical Diseases, such as Leishmaniases, presenting the advantage of reducing both costs and duration of the drug discovery process. In previous work, our group developed a Machine Learning pipeline for the repurposing of FDA-approved drugs against Leishmania parasites. The present study is focused on an in vitro validation of this approach by assessing the antileishmanial effects of 10 predicted drug candidates. First, we evaluated the drugs' activity against promastigotes from two strains of L. infantum and one of L. major, which caused distinct clinical manifestations, using an MTT assay. The standard anti-Leishmania drug Amphotericin B was used as a positive control. Five molecules demonstrated anti-Leishmania effects, out of which Acebutolol, Prilocaine and Phenylephrine are described herein for the first time. When tested on promastigote growth, Acebutolol displayed IC50 values ranging from 69.28 to 145.53 µg/mL. Prilocaine exhibited IC50 values between 33.10 and 45.81 µg/mL. Phenylephrine, on the other hand, presented IC50 values >200 µg/mL. The two remaining drugs, Dibucaine and Domperidone, exhibited significantly low IC50 values varying between 0.58 and 1.05 µg/mL, and 6.30 and 8.17 µg/mL, respectively. Both compounds were previously described as anti-Leishmania agents in vivo. All five compounds demonstrated no notable cytotoxic effects on THP-1-derived macrophages at the IC50 concentrations, allowing for their testing on the intracellular form of L. major and L. infantum parasites. Interestingly, all compounds exhibited antileishmanial activity on amastigotes with enhanced IC50 values compared to the corresponding promastigotes. Noticeably, Dibucaine and Domperidone displayed IC50 values of at most 1.99 µg/mL. Acebutolol, Prilocaine and Phenylephrine showed IC50 values ranging from 13.84 to 66.81 µg/mL. Our previously published Computer-Aided repositioning pipelines of FDA-approved drugs as antileishmanial agents identified Dibucaine and Domperidone as candidates in support of previous in vivo studies. This study consolidates such findings through the in vitro validation against 2 Leishmania species, highly prevalent in Africa and Middle East, and reveals Acebutolol, Prilocaine, and Phenylephrine as novel anti-Leishmania effectors, confirming the relevance of our approach and calling for further investigations.

Triose Phosphate Isomerase Structure-Based Virtual Screening and In Vitro Biological Activity of Natural Products as Leishmania mexicana Inhibitors.

Cutaneous leishmaniasis (CL) is a public health problem affecting more than 98 countries worldwide. No vaccine is available to prevent the disease, and available medical treatments cause serious side effects. Additionally, treatment failure and parasite resistance have made the development of new drugs against CL necessary. In this work, a virtual screening of natural products from the BIOFACQUIM and Selleckchem databases was performed using the method of molecular docking at the triosephosphate isomerase (TIM) enzyme interface of Leishmania mexicana (L. mexicana). Finally, the in vitro leishmanicidal activity of selected compounds against two strains of L. mexicana, their cytotoxicity, and selectivity index were determined. The top ten compounds were obtained based on the docking results. Four were selected for further in silico analysis. The ADME-Tox analysis of the selected compounds predicted favorable physicochemical and toxicological properties. Among these four compounds, S-8 (IC50 = 55 µM) demonstrated a two-fold higher activity against the promastigote of both L. mexicana strains than the reference drug glucantime (IC50 = 133 µM). This finding encourages the screening of natural products as new anti-leishmania agents.

Zinc(II)-Sterol Hydrazone Complex as a Potent Anti-Leishmania Agent: Synthesis, Characterization, and Insight into Its Mechanism of Antiparasitic Action.

Searching for new alternatives for treating leishmaniasis, we present the synthesis, characterization, and biological evaluation against Leishmania amazonensis of the new ZnCl2(H3)2 complex. H3 is 22-hydrazone-imidazoline-2-yl-chol-5-ene-3β-ol, a well-known bioactive molecule functioning as a sterol Δ24-sterol methyl transferase (24-SMT) inhibitor. The ZnCl2(H3)2 complex was characterized by infrared, UV-vis, molar conductance measurements, elemental analysis, mass spectrometry, and NMR experiments. The biological results showed that the free ligand H3 and ZnCl2(H3)2 significantly inhibited the growth of promastigotes and intracellular amastigotes. The IC50 values found for H3 and ZnCl2(H3)2 were 5.2 µM and 2.5 µM for promastigotes, and 543 nM and 32 nM for intracellular amastigotes, respectively. Thus, the ZnCl2(H3)2 complex proved to be seventeen times more potent than the free ligand H3 against the intracellular amastigote, the clinically relevant stage. Furthermore, cytotoxicity assays and determination of selectivity index (SI) revealed that ZnCl2(H3)2 (CC50 = 5 μΜ, SI = 156) is more selective than H3 (CC50 = 10 μΜ, SI = 20). Furthermore, as H3 is a specific inhibitor of the 24-SMT, free sterol analysis was performed. The results showed that H3 was not only able to induce depletion of endogenous parasite sterols (episterol and 5-dehydroepisterol) and their replacement by 24-desalkyl sterols (cholesta-5,7,24-trien-3β-ol and cholesta-7,24-dien-3β-ol) but also its zinc derivative resulting in a loss of cell viability. Using electron microscopy, studies on the fine ultrastructure of the parasites showed significant differences between the control cells and parasites treated with H3 and ZnCl2(H3)2. The inhibitors induced membrane wrinkle, mitochondrial injury, and abnormal chromatin condensation changes that are more intense in the cells treated with ZnCl2(H3)2.

In Vitro Antiparasitic Activities of Monovalent Ionophore Compounds for Human and Canine Leishmaniases.

Simple SummaryThe leishmaniases are vector-borne, neglected diseases caused by parasites of the genus Leishmania, widely diffused around the globe. Clinical manifestations range from localized cutaneous and mucocutaneous lesions to the visceral form, with potentially fatal outcomes. Associated with malnutrition, a weak immune system, and no access to health-care facilities, these conditions affect the poorest populations worldwide. In addition, dogs develop a multisystemic and fatal disease, and act as the main parasite reservoir for some Leishmania species. Currently, human, and canine leishmaniases share the same treatment, which includes very few, difficult to administer, expensive, and toxic drugs. Moreover, drug resistance is increasingly spreading, and there is no human vaccine. Therefore, improved and safer treatments are a high priority. Here, monovalent ionophores (salinomycin, monensin, and nigericin) were repurposed in vitro for their leishmanicidal abilities against both insect-stage parasites (promastigotes) and intracellular forms (amastigotes) within human and primary canine macrophages. These compounds showed similar antiparasitic effects against distinct Leishmania spp. promastigotes. Interestingly, a differential and host-specific anti-amastigote efficacy was observed, being these compounds more active against human- than canine-infected macrophages. Altogether, these data indicate a potential application of ionophores against Leishmania infections and challenge the concept that the same compounds may be equally effective against both human and canine leishmaniases.The leishmaniases are vector-borne parasitic diseases affecting humans and animals, with high mortality rates in endemic countries. Infected dogs represent the main reservoir of infection. Disease control is mainly based on chemotherapy, which, at present, shows serious drawbacks both in humans and dogs. Therefore, the discovery or repurposing of new treatments is mandatory. Here, three monovalent ionophores (salinomycin, monensin, nigericin) were tested against promastigotes of Leishmania (L.) infantum, Leishmania tropica, and Leishmania braziliensis, and against amastigotes of L. infantum within human and, for the first time, canine macrophages. All three drugs were leishmanicidal against all Leishmania spp. promastigotes with IC50 values between 7.98 and 0.23 µM. Monensin and nigericin showed IC50 values < 1 µM, whereas salinomycin was the least active compound (IC50 > 4 µM). Notably, the ionophores killed L. infantum amastigotes within human THP-1 cells with IC50 values ranging from 1.67 to 1.93 µM, but they only reduced by 27–37% the parasite burden in L. infantum-infected canine macrophages, showing a host-specific efficacy. Moreover, a selective higher toxicity against canine macrophages was observed. Overall, repurposed ionophores have the potential to be further investigated as anti-Leishmania agents, but different drug options may be required to tackle human or canine leishmaniases.

Synthesis of some novel 8-(4-Alkylpiperazinyl) caffeine derivatives as potent anti-Leishmania agents

In this paper, the synthesis, characterization and the leishmanicidal assessments of novel 8-(4-alkylpiperazinyl) caffeine derivatives have been described. These compounds are new caffeine hybrid molecules that are structurally composed of three compartments comprising caffeinyl, piperazinyl and N-alkyl/aryl residues. The synthesis was carried out through the bromination of caffeine via NBS to attain the 8-bromocaffeine (8-BC) followed by the SNAr-type reaction with the piperazine which afforded the 8‑piperazinyl caffeine (8-PC). Ultimately, the N-alkylation of 8-PC with diverse alkyl halides acquired the products in good to excellent yields (68–96 %). The in vitro evaluation of synthesized compounds on promastigotes of Leishmania major (MHOM/IR/2002/Mash2) has showed that compounds 9d (ie: 8-(4-heptylpiperazin-1-yl)-1,3,7-trimethyl-1H-purine-2,6(3H,7H)-dione), 9e (ie: 1,3,7-trimethyl-8-(4-octylpipera zin-1-yl)-1H-purine-2,6(3H,7H)-dione) and 9f (ie: 8-(4-decylpiperazin-1-yl)-1,3,7-trimethyl-1H-purine-2,6(3H,7H)-dione) with IC50 = 84 μM, IC50 = 94 μM and IC50 = 89 μM displayed remarkable leishmanicidal activity even stronger than metronidazole (MTZ) and miltefosine as the reference drugs. The SAR analysis indicated the leishmanicidal activity of title compounds depended upon the type of substituents on N4 of piperazine. The in silico physicochemical properties, pharmacokinetic profile, and drug likeness predictions were also carried out for the all synthesized compounds and MTZ. The molecular docking study was also conducted to predict the binding mode and the interaction of 9d as the most and 9a as the least active compounds with pteridine reductase 1 (PTR1) enzyme. The docking results determined that 9d exhibited a strong binding affinity to the active site of the enzyme.

N6-modification of 7-Deazapurine nucleoside analogues as Anti-Trypanosoma cruzi and anti-Leishmania agents: Structure-activity relationship exploration and In vivo evaluation

Chagas disease and leishmaniasis are two poverty-related neglected tropical diseases that cause high mortality and morbidity. Current treatments suffer from severe limitations and novel, safer and more effective drugs are urgently needed. Both Trypanosoma cruzi and Leishmania are auxotrophic for purines and absolutely depend on uptake and assimilation of host purines. This led us to successfully explore purine nucleoside analogues as chemotherapeutic agents against these and other kinetoplastid infections. This study extensively explored the modification of the 6-amino group of tubercidin, a natural product with trypanocidal activity but unacceptable toxicity for clinical use. We found that mono-substitution of the amine with short alkyls elicits potent and selective antitrypanosomal and antileishmanial activity. The methyl analogue 15 displayed the best in vitro activity against both T. cruzi and L. infantum and high selectivity versus host cells. Oral administration for five consecutive days in an acute Chagas disease mouse model resulted in significantly reduced peak parasitemia levels (75, 89 and 96% with 12.5, 25 and 50 mg/kg/day, respectively). as well as increased animal survival rates with the lower doses (83 and 67% for 12.5 and 25 mg/kg/day, respectively).

Applied Machine Learning Toward Drug Discovery Enhancement: Leishmaniases as a Case Study.

Drug discovery (DD) research is a complex field with a high attrition rate. Machine learning (ML) approaches combined to chemoinformatics are of valuable input to this field. We, herein, focused on implementing multiple ML algorithms that shall learn from different molecular fingerprints (FPs) of 65 057 molecules that have been identified as active or inactive against Leishmania major promastigotes. We sought to build a classifier able to predict whether a given molecule has the potential of being anti-leishmanial or not. Using the RDkit library, we calculated 5 molecular FPs of the molecules. Then, we implemented 4 ML algorithms that we trained and tested for their ability to classify the molecules into active/inactive classes based on their chemical structure, encoded by the molecular FPs. Best performers were random forest (RF) and support vector machine (SVM), while atom-pair and topology torsion FPs were the best embedding functions. Both models were further assessed on different stratification levels of the dataset and showed stable performances. At last, we used them to predict the potential of molecules within the Food and Drug Administration (FDA)-approved drugs collection to present anti-Leishmania effects. We ranked these drugs according to their anti-Leishmanial probability and obtained in total seven anti-Leishmania agents, previously described in the literature, within the top 10 of each model. This validates the robustness of the approach, the algorithms, and FPs choices as well as the importance of the dataset size and content. We further engaged these molecules into reverse docking experiments on 3D crystal structures of seven well-studied Leishmania drug targets and could predict the molecular targets for 4 drugs. The results bring novel insights into anti-Leishmania compounds.

Limonene-carvacrol: A combination of monoterpenes with enhanced antileishmanial activity

BackgroundLeishmaniasis is a parasitosis with a wide incidence in developing countries. The drugs which are indicated for the treatment of this infection usually are able to promote high toxicity. PurposeA combination of limonene and carvacrol, monoterpenes present in plants with antiparasitic activity may constitute an alternative for the treatment of these diseases. MethodsIn this study, the antileishmania activity against Leishmania major, cytotoxicity tests, assessment of synergism, parasite membrane damage tests as well as molecular docking and immunomodulatory activity of limonene–carvacrol (Lim–Car) combination were evaluated. ResultsThe Lim–Car combination (5:0; 1:1; 1:4; 2:3; 3:2; 4:1 and 0:5) showed potential antileishmania activity, with mean inhibitory concentration (IC50) ranging from 5.8 to 19.0 μg.mL−1. They demonstrated mean cytotoxic concentration (CC50) ranging from 94.1 to 176.0 μg.mL−1, and did not show significant hemolytic effect. In the investigation of synergistic interaction, the 4:1 Lim–Car combination showed better fractional inhibitory concentration (FIC) index as well as better activity on amastigotes and IS. The samples caused considerable damage to the parasite membrane this monoterpene activity seems to be more related to Trypanothione Reductase (TryR) enzyme interaction, demonstrated in the molecular docking assay. In addition, the 4:1 Lim–Car combination stimulated macrophage activation, and showed at was the best association, with reduction of infection and infectivity of parasitized macrophages. ConclusionThe 4:1 Lim–Car combination appears to be a promising candidate as a monotherapeutic antileishmania agent.

In vitro antileishmanial and immunomodulatory activities of the synthetic analogue riparin E

Leishmaniases are infectious diseases caused by protozoa of the genus Leishmania, that may have different clinical manifestations. First line drugs used in the treatment of leishmaniosis are high costly, and are very aggressive requiring medical monitoring. Thus new therapeutic alternatives are needed and, in this context, natural products have been considered as a source of new antileishmania agents. Riparins are alkamides found in the unripe fruits of Aniba riparia. Several biological activities are described for this group of compounds, such as antimicrobial and antiparasitic potential. The objective of this work was to evaluate the anti-leishmania activity riparin E (Rip-E) in vitro, against promastigotes and internalized amastigotes of Leishmania amazonensis. Rip-E was able to inhibit promastigote cell growth (IC50 4.7 μg/ml) and to reduce the percentage of macrophages infected with amastigotes, reducing its infectivity (survival index) (IC50 1.3 μg/ml). The cytotoxicity against BALB/c murine macrophages was also assessed (CC50 50.6 μg/ml) and the selectivity index was 38.9. Rip-E also demonstrated immunomodulatory activity, evidenced by the increase of the phagocytic capacity and lysosomal activity. However, Rip-E did not affect directly the production of nitric oxide. These results suggest that Rip-E has antileishmania potential, by both its direct inhibitory effect and its ability to activate macrophages.

Carvacrol loaded nanostructured lipid carriers as a promising parenteral formulation for leishmaniasis treatment

Leishmaniasis are a group of neglected infectious diseases caused by protozoa of the genus Leishmania with distinct presentations. The available leishmaniasis treatment options are either expensive and/or; cause adverse effects and some are ineffective for resistant Leishmania strains. Therefore, molecules derived from natural products as the monoterpene carvacrol, have attracted interest as promising anti-leishmania agents. However, the therapeutic use of carvacrol is limited due to its low aqueous solubility, rapid oxidation and volatilization. Thus, the development of nanostructured lipid carriers (NLCs) was proposed in the present study as a promising nanotechnology strategy to overcome these limitations and enable the use of carvacrol in leishmaniasis therapy. Carvacrol NLCs were obtained using a warm microemulsion method, and evaluated regarding the influence of lipid matrix and components concentration on the NLCs formation. NLCs were characterized by DSC and XRD as well. In addition, to the in vitro carvacrol release from NLCs, the in vitro cytotoxicity and leishmanicidal activity assays, and the in vivo pharmacokinetics evaluation of free and encapsulated carvacrol were performed. NLCs containing carvacrol were obtained successfully using a warm microemulsion dilution method. The NLCs formulation with the lowest particle size (98.42 ± 0.80 nm), narrowest size distribution (suitable for intravenous administration), and the highest encapsulation efficiency was produced by using beeswax as solid lipid (HLB=9) and 5% of lipids and surfactant. The in vitro release of carvacrol from NLCs was fitted to the Korsmeyer and Peppas, and Weibull models, demonstrating that the release mechanism is probably the Fickian diffusion type. Moreover, carvacrol encapsulation in NLCs provided a lower cytotoxicity in comparison to free carvacrol (p<0.05), increasing its in vitro leishmanicidal efficacy in the amastigote form. Finally, the in vivo pharmacokinetics of carvacrol after IV bolus administration suggests that this phenolic monoterpene undergoes enterohepatic circulation and therefore presented a long half-life (t1/2) and low clearance (Cl). In addition, C0, mean residence time (MRT) and Vdss of encapsulated carvacrol were higher than free carvacrol (p < 0.05), favoring a higher distribution of carvacrol in the target tissues. Thus, it is possible to conclude that the developed NLCs are a promising delivery system for leishmaniasis treatment.

Virtual and experimental screening of phenylfuranchalcones as potential anti-Leishmania candidates

Discovery of novel or repurposed chemical treatments for leishmaniasis is a priority given the limited number of therapeutic alternatives available. One way to accelerate the finding is by implementing virtual screening methodologies using structural information, with subsequent experimental validations. Here we tested a library of 48 phenylfuranchalcones as anti-Leishmania agents that can be associated to the potential inhibition of a protein target within the parasite. For that purpose, a list of 43 protein structures from different Leishmania species was prepared to dock the virtual compound library. The protein with the best predicted scores was used as reference to select a subset of previously synthesized compounds for in vitro validation of their cytotoxicity and anti-Leishmania activity. We found a set of active compounds (EC50 < 25 μM) that were compared with the computational results using Spearman correlations. The analysis allowed us to propose the inhibition of a phosphodiesterase enzyme as the potential mechanism of action.

Novel Nanosized Chitosan-Betulinic Acid Against Resistant Leishmania Major and First Clinical Observation of such parasite in Kidney

Regarding the antiparasitic effects of Betulinic acid (B) against Leishmaniasis, it was loaded into nanochitosan (K) for the first time in order to improve its therapeutic effects and decrease its side effects for the treatment of Leishmania major-infected Balb/c mice. Improvement the therapeutic efficacy of Bas an anti-leishmania agent through increasing the effective dose was achieved by using a novel solvent and phase separation method for K synthesis. The synthesized K with the size of 102 nm and Betulinic acid-nanochitosan (BK) with the size of 124 nm and drug loading efficiency of 93%, cellular uptake of 97.5% with the slow drug release pattern was prepared. To increase the therapeutic dose, a modified 10% acetic acid solvent was used. The in vitro and in vivo results showed that the nanodrug of BK was non toxic by 100% and BK20 mg/kg could completely performed the wound healing and inhibit the parasite in a large extent (P ˂ 0.001) compared to other groups. Therefore, BK could be considered as an alternative regimen for treatment of L. major.

Leishmanicidal activity of α-bisabolol from Tunisian chamomile essential oil.

According to the World Health Organization, leishmaniasis is considered as a major neglected tropical disease causing an enormous impact on global public health. Available treatments were complicated due to the high resistance, toxicity, and high cost. Therefore, the search for novel sources of anti-leishmania agents is an urgent need. In the present study, an in vitro evaluation of the leishmanicidal activity of the essential oil of Tunisian chamomile (Matricaria recutita L.) was carried out. Chamomile essential oil exhibits a good activity on promastigotes forms of L. amazonensis and L. infantum with a low inhibitory concentration at 50% (IC50) (10.8 ± 1.4 and 10.4 ± 0.6μg/mL, respectively). Bio-guided fractionation was developed and led to the identification of (-)-α-bisabolol as the most active molecule with low IC50 (16.0 ± 1.2 and 9.5 ± 0.1μg/mL for L. amazonensis and L. infantum, respectively). This isolated sesquiterpene alcohol was studied for its activity on amastigotes forms (IC50 = 5.9 ± 1.2 and 4.8 ± 1.3μg/mL, respectively) and its cytotoxicity (selectivity indexes (SI) were 5.4 and 6.6, respectively). The obtained results showed that (-)-α-bisabolol was able to activate a programmed cell death process in the promastigote stage of the parasite. It causes phosphatidylserine externalization and membrane damage. Moreover, it decreases the mitochondrial membrane potential and total ATP levels. These results highlight the potential use of (-)-α-bisabolol against both L. amazonensis and L. infantum, and further studies should be undertaken to establish it as novel leishmanicidal therapeutic agents.

In vitro 4-Aryloxy-7-chloroquinoline derivatives are effective in mono- and combined therapy against Leishmania donovani and induce mitocondrial membrane potential disruption

The present study evaluates in vitro the effect of two synthetic compounds of the 7-chloro-4-aryloxyquinoline series, QI (C17H12ClNO3) and QII (C18H15ClN4O2S), on Leishmania donovani parasites. The results obtained demonstrate that these compounds are able to inhibit the proliferation of L. donovani promastigotes in a dose-dependent way (QI IC50 = 13.03 ± 3.4 and QII IC50 = 7.90 ± 0.6 μM). Likewise, these compounds significantly reduced the percentage of macrophage infection by amastigotesand the number of amastigotes within macrophage phagolysosomes, the clinical relevant phase of these parasites. Compound QI showed an IC50 value of 0.66 ± 0.2 μM, while for derivative QII, the corresponding IC50 was 1.02 ± 0.17 μM. Interestingly, the amastigotes were more susceptible to the drug treatment when compared to promastigotes. Furthermore, no cytotoxic effect of these compounds was observed on the macrophage cell line at the concentrations tested. The combination of these compounds with miltefosine and amphotericin B on both parasite morphotypes was evaluated. The isobolograms showed a synergistic effect for both combinations; with a Fractional Inhibitory Concentration (FIC) Index lower than 1 for promastigotes and less than 0.3 for intracellular amastigotes. The effect of QI and QII on mitochondrial membrane potential was also studied. The combination of quinolone derivatives compounds with miltefosine and amphotericin B showed 5–8-fold stronger depolarization of membrane mitochondrial potential when compared to drugs alone. The present work validates the combination of drugs as an effective alternative to potentiate the action of anti-Leishmania agents and points to the quinoline compounds studied here as possible leishmanicidal drugs.

Sodium Stibogluconate Treatment for Cutaneous Leishmaniasis : A Clinical Study of 43 Cases from the North of Jordan

Objective: to study the efficacy of Sodium Stibogluconate intramuscular injections in the treatment of cutaneous leishmaniasis, safety and side effects. Method: A total 43 patients were seen over a period of 12 months, from January 2009 to December 2010. All cases were seen at Prince Rashed Military Hospital in the north of Jordan. The diagnosis of localized cutaneous leishmania was made on clinical grounds proved by leishmania smear or skin biopsy. The distribution of patients according to gender, age groups, time of the year, was made. The criteria for sodium stibogluconate injection were: the severity of symptoms, site of lesion on face (ear, nose and cheek), and multiplicity of lesions. The dose of sodium stibogluconate given was 10 mg\kg given as intramuscular injections daily for total two weeks followed by complete blood count, liver function test, electrocardiogram as base line. Results: 23 patients were males and 20 were females (16 of them were 14 years and below). The age group ranged from 2-72 years. One patient (2.3%) had resistant infection to sodium stibogluconate; and an admission was for one patient (2, 3%) for a few days because of a picture of Hepatotoxicity. 42 patients showed improvement of the lesion (98%); improvement is defined when the lesion flattens and ulceration disappears. One patient (2.3%) demonstrated increase in liver enzymes after one week of treatment’ upon stopping treatment for one week the patient then resumes treatment with no complications and with complete remission. Conclusion: Many cases of cutaneous leishmaniasis are seen in Jordan causing cosmetic problems. Early introduction of systemic anti-leishmania agent is recommended. Sodium stibogluconate is an effective way to decrease scarring and dispigmentation, with minimum side effects.

QSAR study of chalcone derivatives as anti-Leishmania agents

Quantitative structure activity relationship analyses were used to identify the ideal physicochemical characteristics of potential chalcone derivatives as anti-Leishmania agents. The HyperChem program was used to build chalcone structures and to perform conformational analyses through the semiempirical method followed by the PM3 force field. Dragon calculated a large number of molecular descriptors. Multilinear regression was used for quantitative structure activity relationship modeling. Based on our computational studies, 4 descriptors, SEigv, RDF125v, RDF055u, and O-058, can affect the activity of chalcone derivatives.