The effect of verapamil on in vitro susceptibility of promastigote and amastigote stages of Leishmania tropica to meglumine antimoniate

Efficacy Evaluation of 10-Hydroxy Chondrofoline and Tafenoquine against Leishmania tropica (HTD7)

Leishmaniasis is affirmed as a category one disease (most emerging and unmanageable) by the World Health Organization (WHO), affecting 98 countries with an annual global incidence of ~1.2 million cases. Options for chemotherapeutic treatment are limited due to drug resistance and cytotoxicity. Thus, the search for new chemical compounds is instantly desirable. In this study, we used two compounds, i.e., 10-hydroxy chondrofoline and tafenoquine, for their antileishmanial activity against L. tropica (HTD₇). First, the cytotoxicity assay of the test compounds against THP-1 cells was carried out, and these compounds were found safe. Intra-THP-1 amastigote activity (in vitro) was performed, which was then followed by the in vivo activity of 10-hydroxy chondrofoline in the murine cutaneous leishmaniasis (CL) model. A total of three concentrations were used, i.e., 25, 50, and 100 µM, to check the in vitro activity of the test compounds against the amastigotes. 10-hydroxy chondrofoline was found to be the most potent compound in vitro (and thus was selected for in vivo studies) with an LD₅₀ value of 43.80 µM after 48 h incubation, whilst tafenoquine had an LD₅₀ value of 53.57 µM. In vivo activity was conducted by injecting 10-hydroxy chondrofoline in the left hind foot of the infected BALB/c mice, where it caused a statistically significant 58.3% (F = 14.18; p = 0.002) reduction in lesion size (0.70 ± 0.03 mm) when compared with negative control (1.2 ± 0.3 mm).

Antiproliferative properties of Turmerone on Leishmania major: Modes of action confirmed by antioxidative and immunomodulatory roles

Treatment of leishmaniasis by conventional synthetic compounds has faced a serious challenge worldwide. This study was performed to evaluate the effect and modes of action of aromatic Turmerone on the Leishmania major intra-macrophage amastigotes, the causative agent of zoonotic cutaneous leishmaniasis in the Old World. In the findings, the mean numbers of L. major amastigotes in macrophages were significantly decreased in exposure to Turmerone plus meglumine antimoniate (Glucantime®; MA) than MA alone, especially at 50 µg/mL. In addition, Turmerone demonstrated no cytotoxicity as the selectivity index (SI) was 21.1; while it induced significant apoptosis in a dose-dependent manner on L. major promastigotes. In silico molecular docking analyses indicated an affinity of Turmerone to IL-12, with the MolDock score of - 96.8 kcal/mol; which may explain the increased levels of Th1 cytokines and decreased level of IL-10. The main mechanism of action is more likely associated with stimulating a powerful antioxidant and promoting the immunomodulatory roles in the killing of the target organism.

Nanoparticles Loaded with a New Thiourea Derivative: Development and In vitro Evaluation Against Leishmania amazonensis

BACKGROUND

Leishmaniasis is a neglected tropical disease caused by protozoa of the genus Leishmania. Current treatments are restricted to a small number of drugs that display both severe side effects and a potential for parasites to develop resistance. A new N-(3,4-methylenedioxyphenyl)-N'- (2-phenethyl) thiourea compound (thiourea 1) has shown promising in vitro activity against Leishmania amazonensis with an IC₅₀ of 54.14 μM for promastigotes and an IC₅₀ of 70 μM for amastigotes.

OBJECTIVE

To develop a formulation of thiourea 1 as an oral treatment for leishmaniasis, it was incorporated into Nanoparticles (NPs), a proven approach to provide long-acting drug delivery systems.

METHODS

Poly (D,L-Lactic-co-Glycolic Acid) (PLGA) polymeric NPs containing thiourea 1 were obtained through a nanoprecipitation methodology associated with solvent evaporation. The NPs containing thiourea 1 were characterized for Encapsulation Efficiency (EE%), reaction yield (% w/w), surface charge, particle size and morphology by Transmission Electron Microscopy (TEM).

RESULTS

NPs with thiourea 1 showed an improved in vitro leishmanicidal activity with a reduction in its cytotoxicity against macrophages (CC₅₀>100 μg/mL) while preserving its IC₅₀ against intracellular amastigotes (1.46 ± 0.09 μg/mL). This represents a parasite Selectivity Index (SI) of 68.49, which is a marked advancement from the reference drug pentamidine (SI = 30.14).

CONCLUSION

The results suggest that the incorporation into NPs potentiated the therapeutic effect of thiourea 1, most likely by improving the selective delivery of the drug to the phagocytic cells that are targeted for infection by L. amazonensis. This work reinforces the importance of nanotechnology in the acquisition of new therapeutic alternatives for oral treatments.

The Fraction of the Snake Venom, Its Leishmanicidal Effect, and the Stimulation of an Anti-Leishmania Response in Infected Macrophages

BACKGROUND AND AIMS

Due to the lack of an effective vaccine and complexity of the control measures against vectors and reservoir hosts, the control of leishmaniasis depends primarily on chemotherapy. This study was aimed to assess the snake venom, Naja naja oxiana fraction 11(NNOVF11) on Leishmania infantum and its broad mode of action.

METHODS

A wide range of in vitro advanced assays including high-performance liquid chromatography (HPLC), MTT (3-[4, 5-Dimethylthiazol-2-yl]-2, 5diphenyltetrazolium bromide; Thiazolyl blue), macrophage assays, quantitative real-time polymerase chain reaction (qPCR), flow cytometry and enzyme- linked immunosorbent assay (ELISA) on L. infantum promastigote and amastigote stages were used. IC₅₀ values of L. infantum stages, CC₅₀ value, and apoptosis were also analyzed.

RESULTS

The NNOV-F11 demonstrated strong antileishmanial activity against L. infantum stages in a dose-dependent manner compared to the untreated control group. Interleukin (IL)-12, TNF-α, and iNOS genes expression as the indicators of T helper(h)1 response significantly increased; in contrast, the expression level of IL-10, as the representative of Th2 response significantly decreased (p < 0.001). Reactive oxygen species (ROS) detection showed a significant increase (p < 0.001) after treatment with different concentrations of NNOV-F11, unlike arginase (ARG) activity, which displayed a significant reduction (p < 0.001).

CONCLUSION

NNOV-F11 possessed a potent inhibitory effect on L. infantum stages with the multifunctional and broad mode of actions, which promoted the immunomodulatory role, induced ROS production, stimulated apoptotic-like mechanisms, and inhibited L-ARG activity, which collectively led to the parasite death. Further studies are crucial to assess the effect of the NNOV-F11 on animal models or clinical settings.

Leishmanicidal potentials of Gossypium hirsutum extract and its fractions on Leishmania major in a murine model: parasite burden, gene expression, and histopathological profile

Introduction. Leishmaniasis is a neglected tropical and subtropical disease caused by over 20 protozoan species.Hypothesis. Treatment of this complex disease with traditional synthetic drugs is a major challenge worldwide. Natural constituents are unique candidates for future therapeutic development.Aim. This study aimed to assess the in vivo anti-leishmanial effect of the Gossypium hirsutum extract, and its fractions compared to the standard drug (Glucantime, MA) in a murine model and explore the mechanism of action.Methodology. Footpads of BALB/c mice were infected with stationary phase promastigotes and treated topically and intraperitoneally with G. hirsutum extract, its fractions, or Glucantime, 4 weeks post-infection. The extract and fractions were prepared using the Soxhlet apparatus with chloroform followed by the column procedure.Results. The crude extract significantly decreased the footpad parasite load and lesion size compared to the untreated control group (P<0.05), as revealed by dilution assay, quantitative real-time PCR, and histopathological analyses. The primary mode of action involved an immunomodulatory role towards the Th1 response in the up-regulation of IFN-γ and IL-12 and the suppression of IL-10 gene expression profiling against cutaneous leishmaniasis caused by Leishmania major.Conclusion. This finding suggests that the extract possesses multiple combinatory effects of diverse bioactive phytochemical compositions that exert its mechanisms of action through agonistic-synergistic interactions. The topical extract formulation could be a suitable and unique candidate for future investigation and pharmacological development. Further studies are crucial to evaluate the therapeutic potentials of the extract alone and in combination with conventional drugs using clinical settings.

The Effect of Naja naja oxiana Snake Venom Against Leishmania tropica Confirmed by Advanced Assays

PURPOSE

The aim of this study was to explore the activity of Naja naja oxiana venom on Leishmania tropica and its modes of action.

METHODS

Different fractions of Naja naja oxiana venom (NNOV) were prepared and characterized by high-performance liquid chromatography. The superior component, fraction k (FK) was selected. The activity of the fraction was assessed using advanced assays.

RESULTS

Interleukin (IL)-12, TNF-α and iNOS gene expression as the indicators of Th1 significantly increased. In contrast, the level of IL-10, as the marker of T helper 2 substantially decreased (p < 0.001). Reactive oxygen species (ROS) detection showed a significant increase (p < 0.001) after treatment with different concentrations of NNOV-FK, unlike arginase (L-ARG) activity which showed a significant reduction (p < 0.001). The NNOV-FK showed significant lethal activity on the L. tropica stages.

CONCLUSION

The findings demonstrated that NNOV-FK represented a strong leishmanicidal activity on L. tropica stages. The major modes of NNOV-FK action are multidimensional, which perceives the induction of a synergistic response and upregulation of the immune-modulatory role towards Th1 response against L. tropica stages as well as apoptotic and anti-metabolic action as a model drug to generate ROS, block the polyamine synthesis and lead to parasite death.

The emerging paradigm of calcium homeostasis as a new therapeutic target for protozoan parasites

Calcium channels (CCs), a group of ubiquitously expressed membrane proteins, are involved in many pathophysiological processes of protozoan parasites. Our understanding of CCs in cell signaling, organelle function, cellular homeostasis, and cell cycle control has led to improved insights into their structure and functions. In this article, we discuss CCs characteristics of five major protozoan parasites Plasmodium, Leishmania, Toxoplasma, Trypanosoma, and Cryptosporidium. We provide a comprehensive review of current antiparasitic drugs and the potential of using CCs as new therapeutic targets. Interestingly, previous studies have demonstrated that human CC modulators can kill or sensitize parasites to antiparasitic drugs. Still, none of the parasite CCs, pumps, or transporters has been validated as drug targets. Information for this review draws from extensive data mining of genome sequences, chemical library screenings, and drug design studies. Parasitic resistance to currently approved therapeutics is a serious and emerging threat to both disease control and management efforts. In this article, we suggest that the disruption of calcium homeostasis may be an effective approach to develop new anti-parasite drug candidates and reduce parasite resistance.

The potential therapeutic role of PTR1 gene in non-healing anthroponotic cutaneous leishmaniasis due to Leishmania tropica

BACKGROUND

Drug resistance is a common phenomenon frequently observed in countries where leishmaniasis is endemic. Due to the production of the pteridine reductase enzyme (PTR1), drugs lose their efficacy, and consequently, the patient becomes unresponsive to treatment. This study aimed to compare the in vitro effect of meglumine antimoniate (MA) on non- healing Leishmania tropica isolates and on MA transfected non-healing one to PTR1.

METHODS

Two non-healing and one healing isolates of L. tropica were collected from patients who received two courses or one cycle of intralesional MA along with biweekly liquid nitrogen cryotherapy or systemic treatment alone, respectively. After confirmation of L. tropica isolates by polymerase chain reaction (PCR), the recombinant plasmid pcDNA-rPTR (antisense) was transfected via electroporation and cultured on M199. Isolates in form of promastigotes were treated with different concentrations of MA and read using an enzyme-linked immunosorbent assay (ELISA) reader and the half inhibitory concentration (IC50 ) value was calculated. The amastigotes were grown in mouse macrophages and were similarly treated with various concentrations of MA. The culture glass slides were stained, and the mean number of intramacrophage amastigotes and infected macrophages were assessed in triplicate for both stages.

RESULTS

All three transfected isolates displayed a reduction in optical density compared with the promastigotes in respective isolates, although there was no significant difference between non-healing and healing isolates. In contrast, in the clinical form (amastigotes), there was a significant difference between non-healing and healing isolates (p < 0.05).

CONCLUSION

The results indicated that the PTR1 gene reduced the efficacy of the drug, and its inhibition by antisense and could improve the treatment of non-healing cases. These findings have future implications in the prophylactic and therapeutic modality of non- healing Leishmania isolates to drug.

Cutaneous leishmaniasis in Iran: A systematic review and meta-analysis

Cutaneous leishmaniasis as a public health concern that attracts many attentions in endemic area. There is no exact estimation of cutaneous leishmaniasis in Iran. This study aimed to assess the exact prevalence of disease and carried out in databases including: Pub Med, Google Scholar, Science Direct, Scopus, Web of Science, Magiran, Iran doc, Barakatkns and Scientific Information Database (SID) from 2000 to 2019. Totally 84 studies were eligible to be included in this systematic review and Meta-analysis study. Based on a random effect model the pooled prevalence of leishmaniasis was estimated 45% (95% CI: 39%-51%; I^2 = 99.8%P < 0.001). The highest prevalence of CL was related to Isfahan 66% (53%-78%), Golestan 64% (62%-65%) and Fars province 63% (38%-84%) and the lowest prevalence was estimated in Kermanshah province 4% (4%-5%), Hormozgan 10% (8%-11%), Bushehr 12% (1%-35%) and Kerman 15% (9%-22%) provinces respectively. The lowest prevalence was associated with L. trapica spices 23% (11%-38%) and the highest was associated with L. major spices 32% (21%-45%). The prevalence with both L. trapica and L. major spices was achieved 60% (48%-71%). It is essential for health authorities to take steps to control and prevent the epidemic by rapid treatment of patients, destroying gerbils and promotion of general and health education for the local population.

The potential role and apoptotic profile of three medicinal plant extracts on Leishmania tropica by MTT assay, macrophage model and flow cytometry analysis

Introduction

Treatment of leishmaniasis with conventional synthetic drugs is a major global challenge. This study was designed to explore the leishmanicidal activity and apoptotic profile of three leaf extracts on Leishmania tropica stages.

Methods

The plants of Quercus velutina, Calotropis procera and Nicotiana tabacum were gathered from Anbarabbad county, in the southeastern part of Kerman province and extracted by maceration method using methanol alcohol. Various concentrations of the extracts (1, 10, 100 and 1000 μg/mL) were used against L. tropica stages to evaluate the inhibitory effect by colorimetric assay, macrophage model and flow cytometry. The MTT assay was conducted to determine the IC₅₀ and CC₅₀ values in promastigotes and J774-A1 macrophages, respectively. For intra-macrophage amastigotes, the leishmanicidal activity was evaluated by calculating the mean number of amastigotes in each macrophage and also IC₅₀ values. The promastigote or amastigote stages with no drug and complete medium without organisms were considered as positive and negative controls, respectively. Meglumine antimoniate (Glucantime) was also used as standard drug. Also, annexin V was used to assess the apoptotic profile. All treatment settings were incubated for a standard time of 72 h in triplicates. Data were analyzed by t-test and ANOVA.

Results

The findings showed that all plant extracts inhibited the proliferation rate of promastigotes and amastigotes (P ˂ 0.001); especially, Q. velutina represented the lowest IC₅₀ in both stages. Besides, Q. velutina showed the least number of amastigotes in each macrophage compared to the other groups (4.5 μg/mL). The percentage of parasitic apoptosis at 1000 μg/mL of Q. velutina, C. procera, N. tabacum and Glucantime® were 37.4, 18.6, 8.5 and 52.4, respectively. Amastigotes (clinical stage) were significantly more susceptible to extracts and also Glucantime® than promastigotes (P < 0.001).

Conclusions

This study revealed that all three extracts of Q. velutina, C. procera and N. tabacum exhibited an effective antileishmanial activity and induced apoptosis against the L. tropica promastigotes. Further investigations are essential to isolate and analyze the chemical compositions and their biological properties.

In vitro anti-leishmanial activity of Prunus armeniaca fractions on Leishmania tropica and molecular docking studies

Prunus armeniaca (L.) is a member of the Rosaceae, subfamily Prunoideae, shows anticancer, antitubercular, antimutagenic, antimicrobial, antioxidant, and cardioprotective activities. Here we fractionated the leaves extract of this highly medicinally important plant for antileishmanial activity. In the current study, the leaves extract was fractionated and characterized using column and thin layer chromatography by n-hexane, ethyl acetate, and methanol solvents. Twelve fractions were isolated and subjected for evaluation of their cytotoxicity and in vitro antileishmanial activity against promastigotes and amastigotes of Leishmania tropica. Among all fractions used, the fraction (F7) exhibited the strongest antileishmanial activity. The bioactive fraction was further characterized by spectroscopy (FTIR, UV-Vis), and GC-MS analysis. The in silico docking was carried out to find the active site of PTR1. All derived fractions exhibited toxicity in the safety range IC₅₀ > 100 μg/ml. The fraction (F7) showed significantly the highest antipromastigotes activity with IC₅₀11.48 ± 0.82 μg/ml and antiamastigotes activity with IC₅₀ 21.03 ± 0.98 μg/ml compared with control i.e. 11.60 ± 0.70 and 22.03 ± 1.02 μg/ml respectively. The UV-Vis spectroscopic analysis revealed the presence of six absorption peaks and the FTIR spectrum revealed the presence of alkane, aldehyde, carboxylic acid, thiols, alkynes, and carbonyls compounds The GC-MS chromatogram exhibited the presence of nine compounds: (a) benzeneethanol, alpha, beta dimethyl, (b)carbazic acid, 3-(1 propylbutylidene)-, ethyl ester, (c)1, 2-benzenedicarboxylic acid, diisooctyl ester, (d)benzeneethanamine a-methyl, (e)2aminononadecane, (f)2-heptanamine-5-methyl, (g)cyclobutanol, (h)cyclopropyl carbine, and (i)nitric acid, nonyl ester. Among all compounds, the 1, 2-benzenedicarboxylic acid, diisooctyl ester bound well to the PTR1 receptor. Fraction (F7) showed acceptable results with no cytotoxicity. However, in vivo studies are required in the future.

The potential role of nicotinamide on Leishmania tropica: An assessment of inhibitory effect, cytokines gene expression and arginase profiling

Leishmaniasis represents a major health concern worldwide which has no effective treatment modality. Nicotinamide (NAm) has been used for a wide range of applications from anticancer to antimicrobial usage. This study aimed to assess the effect of NAm combination on Leishmania tropica Inhibition, as well as on cytokines gene expression and arginase (ARG) activity in L. tropica-infected macrophages in an in vitro model. The leishmanicidal effects of NAm and Glucantime (meglumine antimoniate, MA) alone and in combination (NAm/MA) were evaluated using a colorimetric assay and macrophage model. Additionally, immunomodulatory effects and enzymatic activity were assessed by analyzing Th1 and Th2 cytokines gene expression and ARG level, respectively, in infected macrophages treated with NAm and MA, alone and in combination. Findings indicated that the NAm/MA combination demonstrated greater inhibitory effects on L. tropica promastigotes and amastigotes compared with each drug individually. Docking results proved the affinity of NAm to IFN-γ, which can affirm the increased levels of IFN-γ, IL-12p40 and TNF-α as well as reductions in IL-10 secretion with a dose-response effect, especially in the combination group. The NAm/MA combination also showed a significant reduction in the level of ARG activity at all concentrations used compared to each drug individually. These findings indicate higher effectiveness of NAm plus MA in reducing parasite growth, promoting immune response and inhibiting ARG level. This combination should be considered as a potential therapeutic regimen for treatment of volunteer patients with anthroponotic cutaneous leishmaniasis (ACL) in future control programs.

Niosomal formulation of amphotericin B alone and in combination with glucantime: In vitro and in vivo leishmanicidal effects

This study aimed to evaluate the efficacy of glucantime and amphotericin B (AmB) encapsulated in niosome against cutaneous leishmaniasis (CL) using in vitro and in vivo models. The niosomal formulations of the drugs alone and in combination were prepared and characterized. Subsequent to the examination of their cytotoxicity, their efficacy was evaluated using an in vitro MTT assay, macrophage model, flow cytometry, and gene expression profiling. For evaluation of therapeutic effect of niosomal combination on the lesion induced by Leishmania major in inbred BALB/c mice, the size of lesions and number of parasites in spleen was assessed. The niosomal formulations demonstrated significantly greater inhibitory effects compared with the non-niosomal forms when the IC₅₀ was considered. The niosomal combination showed an increase in the apoptotic values and gene expression levels of IL-12 and metacaspase and a decrease in the levels of IL-10 with a dose-response effect. The niosomal combination was also effective in reducing the lesion size and splenic parasite burden in mice. Our findings indicated that there is a synergistic effect between AmB and glucantime in niosomal form in the inhibition of intracellular and extracellular forms of L. tropica. Additionally, the in vivo results on L. major suggest that topical niosomal formulation could be useful in the treatment of CL.

In-vitro and In-vivo Antileishmanial Activity of a Compound Derived of Platinum, Oxaliplatin, against Leishmania Major

This study aimed to evaluate the antileishmanial efficacy of oxaliplatin against Leishmania major (L. major) both in-vitro and in-vivo. The IC50, CC50, and SI of oxaliplatin against promastigotes, murine macrophages, Raw 264.7 cells, and intramacrophage amastigotes of L. major were investigated in-vitro. The effects of this drug on intracellular amastigotes were also assayed, and the percentage of infectivity and IIR were calculated. Flow cytometry was performed to assay apoptosis, using 50 and 100 µg/mL of oxaliplatin in the promastigotes and macrophages. In-vivo, the BALB/c mice were classified into three groups, receiving oxaliplatin, glucantime, and phosphate-buffered saline for one month, respectively. The lesion size, IFN-γ, and IL-4 levels, and parasite burden were also evaluated in the animals. After 72 h, the IC50 and CC50 of oxaliplatin against promastigotes and macrophages were respectively 0.5 and 66.78 µg/mL. The apoptosis of promastigotes and macrophages using 50 µg/mL of oxaliplatin was 7.25% and 2.14%, respectively, while apoptosis induced at 100 µg/mL was 15.48% and 2.80%, respectively. Similar to the glucantime group, the mice treated with oxaliplatin showed a lower parasite burden and smaller lesions, compared with the PBS group (p < 0.01). Furthermore, higher IFN-γ levels were reported in mice receiving oxaliplatin in comparison with those receiving PBS (p < 0.01). The current findings indicated the efficacy of oxaliplatin against promastigote and amastigote forms of Leishmania and L. major-induced leishmaniasis.

Leishmanicidal effects of amphotericin B in combination with selenium loaded on niosome against Leishmania tropica

The strategy for improving the treatment of leishmaniasis by the World Health Organization, is the development of new drugs and combination therapy. The aim of this survey was to investigate the effect of amphotericin B (AmB) in combination with selenium, in a simple or niosomal form, on Leishmania tropica (L. tropica) by in vitro advanced assays. In this study, a niosomal formulation of AmB with selenium was prepared and characterized based on size and morphology. Using MTT assay, macrophage model, flow cytometry, and qPCR, the cytotoxicity and efficiency of the niosomal formulation and simple form of combination were evaluated. No toxicity was reported for both the niosomal and simple form of the combination. The niosomal formulation significantly showed higher inhibitory effect on the promastigote and amastigote forms of L. tropica than simple combination form. Interleukin (IL)-10 significantly decreased while the level of IL-12 and metacasoase as Th-1 activator significantly increased (P < 0.001). The findings of this study indicated that niosomes are the stable carriers for this combination, easy to produce and provide promising results as an effective formulation in the inhibition of extracellular and intracellular forms of L. tropica in compared with simple combination form.

Toxico-pathological effects of meglumine antimoniate on human umbilical vein endothelial cells

Leishmaniasis is one of the most important parasitic diseases after malaria. The standard treatment of leishmaniasis includes pentavalent antimonials (SbV); however, these drugs are associated with serious adverse effects. There have been very few studies pertaining to their side effects and mechanism of action in the fetus. This investigation examines the effects of meglumine antimoniate (MA) on the survival rate, angiogenesis and cellular apoptosis in the human umbilical vein endothelial cells (HUVECs). HUVECs were treated with varying doses of MA (100-800 μg/ml) for 24, 48 and 72 h and the survival rate was studied by colorimetric assay, flow cytometry, immunocytochemistry, migration (scratch) assay and tube formation assay. The results of quantitative real-time PCR (qPCR) studies indicated that the most important genes involved in presenting angiogenesis included VEGF and its receptors (Kdr and Flt-1), NP1 and Hif-1α genes including the anti-apoptotic gene of Bcl2, were significantly reduced compared to the control group (p < 0.05). In contrast, the most leading genes involved in the phenomenon of apoptosis were P53, Bax, Bak, Apaf-1 and caspases 3, 8 and 9, which were significantly up regulated compared to the control group (p < 0.05).

Emerging therapeutic targets for treatment of leishmaniasis

INTRODUCTION

Parasitic diseases that pose a threat to human life include leishmaniasis - caused by protozoan parasite Leishmania species. Existing drugs have limitations due to deleterious side effects like teratogenicity, high cost and drug resistance. This calls for the need to have an insight into therapeutic aspects of disease. Areas covered: We have identified different drug targets via. molecular, imuunological, metabolic as well as by system biology approaches. We bring these promising drug targets into light so that they can be explored to their maximum. In an effort to bridge the gaps between existing knowledge and prospects of drug discovery, we have compiled interesting studies on drug targets, thereby paving the way for establishment of better therapeutic aspects. Expert opinion: Advancements in technology shed light on many unexplored pathways. Further probing of well established pathways led to the discovery of new drug targets. This review is a comprehensive report on current and emerging drug targets, with emphasis on several metabolic targets, organellar biochemistry, salvage pathways, epigenetics, kinome and more. Identification of new targets can contribute significantly towards strengthening the pipeline for disease elimination.

In vitro antileishmanial activity of novel azoles (3-imidazolylflavanones) against promastigote and amastigote stages of Leishmania major

Leishmaniasis is a protozoan infectious disease widely distributed all around the world. First line drugs including antimoniales are insufficient due to resistance in endemic areas and high toxicity. Azole antifungals like ketoconazole (KCZ) are also used as antileishmanial agents for several decades. In the present study, we evaluated in vitro antileishmanial effects of new azole antifungals namely 3-imidazolylflavanones (IFs) and their oximes (IFOs) against Leishmania major (L. major) parasites. The obtained results showed remarkable effect of our compounds on promastigote and amastigote stages of L. major. In particular, the 4-chloro analog of flavanone (IF-2) and 3-chloro substituted flavanone oxime (IFO-3) with IC₅₀ values ≤8.9μg/mL were 8-fold more potent than KCZ (IC₅₀=72μg/mL) against promastigote form of L. major. In amastigote stage, the compounds IF-2 and IFO-2 decreased the mean number of infected macrophages (MIR) more than KCZ (p<0.005). In addition, compounds IF-1, IF-2, IF-4, IFO-2, IFO-3 and IFO-5 decreased the mean number of amastigotes per macrophages (MNAPM) significantly more than KCZ (p<0.005). All compounds decreased both MIR and MNAPM significantly more than control (p<0.001). Compounds IF-2 and IFO-2 with parasite survival of 7.70% and 20% had the highest inhibition on intracellular amastigotes. Although most of compounds displayed acceptable selectivity index, compound IF-2 had the highest CC₅₀ value (115.4μg/mL) and SI (383.3). We concluded that our new synthetic azoles displaying potent activity against L. major could be considered as new hits for drug development in the field of antileishmanial therapy.

Antileishmanial activities of caffeic acid phenethyl ester loaded PLGA nanoparticles against Leishmania infantum promastigotes and amastigotes in vitro

OBJECTIVE

To investigate and compare the antileishmanial effects of CAPE and (CAPE)_{PLGA NPs} on Leishmania infantum (L. infantum) promastigotes and amastigotes in vitro.

METHODS

Efficacies of CAPE, (CAPE)_{PLGA NPs} and free PLGA nanoparticles (NPs) on promastigotes were evaluated using MTT and promastigote count assays, and their anti-amastigote effects were determined via infection index analysis. Griess reaction was also performed to calculate nitric oxide production of macrophages exposed to investigated molecules.

RESULTS

It was determined that CAPE and (CAPE)_{PLGA NPs} demonstrated significant inhibitory effects on L. infantum promastigotes and amastigotes, while free NPs did not exhibit any meaningful antileishmanial effectiveness. The IC₅₀ values of CAPE for L. infantum promastigotes and amastigotes were assessed as (51.0 ± 0.8) and (19.0 ± 1.4) μg/mL, respectively (P < 0.05). On the other side, it was revealed that (CAPE)_{PLGA NPs} had superior antileishmanial activity on both forms of parasites since its IC₅₀ values for L. infantum promastigotes and amastigotes were (32.0 ± 1.3) and (8.0 ± 0.9) μg/mL, respectively (P < 0.05). It was also determined that both agents strongly stimulated nitric oxide production of macrophages.

CONCLUSIONS

The obtained results show that (CAPE)_{PLGA NPs} have a great potential to be especially used in treatment of visceral leishmaniasis; however, in vivo antileishmanial screening of these molecules should be performed in the near future.

Chemical composition along with anti-leishmanial and cytotoxic activity of Zataria multiflora

CONTEXT

Natural products and their compounds are some of the most interesting sources of new drugs. Reviews have reported various pharmacological properties such as antimicrobial effects of Zataria multiflora Boiss (Lamiaceae).

OBJECTIVE

The present study investigates the chemical composition of Z. multiflora essential oil and evaluates its cytotoxic effects and anti-leishmanial activities against Leishmania tropica in an in vitro model.

MATERIALS AND METHODS

The components of Z. multiflora oil were identified by gas chromatography/mass spectroscopy (GC/MS) analysis. Anti-leishmanial effects of the essential oil (0-100 μL/mL) and methanol extract of Z. multiflora (0-100 μg/mL) on promastigote forms as well as their cytotoxic activities against J774 cells were evaluated using MTT assay for 72 h. The leishmanicidal activity against amastigote forms of L. tropica was evaluated at the concentrations of 0-50 μg/mL in a macrophage model for 48 h.

RESULTS

The chemical analyses demonstrated that the main components of essential oil were thymol (41.81%), carvacrol (28.85%), and p-cymene (8.36%). Regarding leishmanicidal activity, the IC50 values for the essential oil and methanol extract were 3.2 μL/mL and 9.8 μg/mL against promastigote forms and 8.3 μL/mL and 34.6 μg/mL against amastigote forms, respectively. Essential oil (CC50 89.3 μL/mL) indicated a higher cytotoxic effect than the methanol extract (CC50 591.6 μg/mL) of Z. multiflora.

CONCLUSION

The present study revealed the chemical composition of Z. multiflora that might be a natural source of new anti-leishmanial agents in terms of use against cutaneous leishmaniasis.

Immucillins Impair Leishmania (L.) infantum chagasi and Leishmania (L.) amazonensis Multiplication In Vitro

Chemotherapy against visceral leishmaniasis is associated with high toxicity and drug resistance. Leishmania parasites are purine auxotrophs that obtain their purines from exogenous sources. Nucleoside hydrolases release purines from nucleosides and are drug targets for anti-leishmanial drugs, absent in mammal cells. We investigated the substrate specificity of the Leishmania (L.) donovani recombinant nucleoside hydrolase NH36 and the inhibitory effect of the immucillins IA (ImmA), DIA (DADMe-ImmA), DIH (DADMe-ImmH), SMIH (SerMe-ImmH), IH (ImmH), DIG (DADMe-ImmG), SMIG (SerMe-ImmG) and SMIA (SerME-ImmA) on its enzymatic activity. The inhibitory effects of immucillins on the in vitro multiplication of L. (L.) infantum chagasi and L. (L.) amazonensis promastigotes were determined using 0.05–500 μM and, when needed, 0.01–50 nM of each drug. The inhibition on multiplication of L. (L.) infantum chagasi intracellular amastigotes in vitro was assayed using 0.5, 1, 5 and 10 μM of IA, IH and SMIH. The NH36 shows specificity for inosine, guanosine, adenosine, uridine and cytidine with preference for adenosine and inosine. IA, IH, DIH, DIG, SMIH and SMIG immucillins inhibited L. (L.) infantum chagasi and L. (L.) amazonensis promastigote growth in vitro at nanomolar to micromolar concentrations. Promastigote replication was also inhibited in a chemically defined medium without a nucleoside source. Addition of adenosine decreases the immucillin toxicity. IA and IH inhibited the NH36 enzymatic activity (Ki = 0.080 μM for IA and 0.019 μM for IH). IA, IH and SMIH at 10 μM concentration, reduced the in vitro amastigote replication inside mice macrophages by 95% with no apparent effect on macrophage viability. Transmission electron microscopy revealed global alterations and swelling of L. (L.) infantum chagasi promastigotes after treatment with IA and IH while SMIH treatment determined intense cytoplasm vacuolization, enlarged vesicles and altered kinetoplasts. Our results suggest that IA, IH and SMIH may provide new chemotherapy agents for leishmaniasis.

In-vitro sensitivity of Pakistani Leishmania tropica field isolate against buparvaquone in comparison to standard anti-leishmanial drugs

In this study, in vitro anti-leishmanial activity of buparvaquone was evaluated against promastigotes and intracellular amastigotes of Pakistani Leishmania tropica isolate KWH23 in relation to the current standard chemotherapy for leishmaniasis (sodium stibogluconate, sodium stibogluconate, amphotericin B and miltefosine). For buparvaquone, mean % inhibition in intracellular amastigotes at four different concentrations (1.35 µM, 0.51 µM, 0.17 µM and 0.057 µM) was 78%, 44%, 20% and 14% respectively, whereas, against promastigotes it was 89%, 77%, 45% and 35% respectively. IC50 values calculated to estimate the anti-leishmanial activity of buparvaquone against intra-cellular amastigotes and promastigotes was 0.53 µM (95% C.I. = 0.32-0.89) and 0.15 µM (95% C.I. = 0.01-1.84) respectively. Amphotericin B was the most potent in-vitro drug tested, with an IC50 of 0.075 µM (95% C.I. = 0.006-0.907) against promastigotes, and 0.065 µM (95% C.I. = 0.048-0.089) against intra-cellular amastigotes. Amphotericin B was more cytotoxic against THP1 cells, with an IC50 of 0.15 µM (95% C.I. = 0.01-0.95) and an apparent in-vitro therapeutic index of 2.0, than was buparvaquone, with an IC50 of 12.03 µM (95% C.I. = 5.36-26.96) against THP1 cells and a therapeutic index of 80.2. The study proposes that buparvaquone may be further investigated as a candidate drug for treatment of cutaneous leishmaniasis.

In Vitro and In Vivo Antileishmanial Effects of Pistacia khinjuk against Leishmania tropica and Leishmania major

The present study aims to evaluate the in vitro and in vivo antileishmanial activities of Pistacia khinjuk Stocks (Anacardiaceae) alcoholic extract and to compare its efficacy with a reference drug, meglumine antimoniate (MA, Glucantime), against Leishmania tropica and Leishmania major. This extract (0-100 µg/mL) was evaluated in vitro against promastigote and intracellular amastigote forms of L. tropica (MRHO/IR/75/ER) and then tested on cutaneous leishmaniasis (CL) in male BALB/c mice with L. major to reproduce the antileishmanial activity topically. In vitro, P. khinjuk extract significantly (P < 0.05) inhibited the growth rate of promastigote (IC50 58.6 ± 3.2 µg/mL) and intramacrophage amastigotes (37.3 ± 2.5 µg/mL) of L. tropica as a dose-dependent response. In the in vivo assay, after 30 days of treatment, 75% recovery was observed in the infected mice treated with 30% extract. After treatment of the subgroups with the concentration of 20 and 30% of P. khinjuk extract, mean diameter of lesions was significantly (P < 0.05) reduced. To conclude, the present investigation demonstrated that P. vera extract had in vitro and in vivo effectiveness against L. major. Obtained findings also provide the scientific evidences that natural plants could be used in the traditional medicine for the prevention and treatment of CL.

Antileishmanial and cytotoxic effects of essential oil and methanolic extract of Myrtus communis L

Plants used for traditional medicine contain a wide range of substances that can be used to treat various diseases such as infectious diseases. The present study was designed to evaluate the antileishmanial effects of the essential oil and methanolic extract of Myrtus communis against Leishmania tropica on an in vitro model. Antileishmanial effects of essential oil and methanolic extract of M. communis on promastigote forms and their cytotoxic activities against J774 cells were evaluated using MTT assay for 72 hr. In addition, their leishmanicidal activity against amastigote forms was determined in a macrophage model, for 72 hr. Findings showed that the main components of essential oil were α-pinene (24.7%), 1,8-cineole (19.6%), and linalool (12.6%). Findings demonstrated that M. communis, particularly its essential oil, significantly (P<0.05) inhibited the growth rate of promastigote and amastigote forms of L. tropica based on a dose-dependent response. The IC₅₀ values for essential oil and methanolic extract was 8.4 and 28.9 μg/ml against promastigotes, respectively. These values were 11.6 and 40.8 μg/ml against amastigote forms, respectively. Glucantime as control drug also revealed IC₅₀ values of 88.3 and 44.6 μg/ml for promastigotes and amastigotes of L. tropica, respectively. The in vitro assay demonstrated no significant cytotoxicity in J774 cells. However, essential oil indicated a more cytotoxic effect as compared with the methanolic extract of M. communis. The findings of the present study demonstrated that M. communis might be a natural source for production of a new leishmanicidal agent.

Antifungal, Antileishmanial, and Cytotoxicity Activities of Various Extracts of Berberis vulgaris (Berberidaceae) and Its Active Principle Berberine

In this study, in vitro antidermatophytic activity against Trichophyton mentagrophytes, Trichophyton rubrum, Microsporum canis, and Microsporum gypseum was studied by disk diffusion test and assessment of minimum inhibitory concentration (MIC) using CLSI broth macrodilution method (M38-A2). Moreover, antileishmanial and cytotoxicity activity of B. vulgaris and berberine against promastigotes of Leishmania major and Leishmania tropica were evaluated by colorimetric MTT assay. The findings indicated that the various extracts of B. vulgaris particularly berberine showed high potential antidermatophytic against pathogenic dermatophytes tested with MIC values varying from 0.125 to >4 mg/mL. The results revealed that B. vulgaris extracts as well as berberine were effective in inhibiting L. major and L. tropica promastigotes growth in a dose-dependent manner with IC50 (50% inhibitory concentration) values varying from 2.1 to 26.6  μ g/mL. Moreover, it could be observed that berberine as compared with B. vulgaris exhibited more cytotoxicity against murine macrophages with CC50 (cytotoxicity concentration for 50% of cells) values varying from 27.3 to 362.6  μ g/mL. Results of this investigation were the first step in the search for new antidermatophytic and antileishmanial drugs. However, further works are required to evaluate exact effect of these extracts in animal models as well as volunteer human subjects.

Effect of root bark extract of Berberis vulgaris L. on Leishmania major on BALB/c mice

Leishmaniasis is one of the most important diseases transmitted by arthropod. This disease is present in 88 countries. Approximately 400 million people are at risk, and 12 million are involved. We aimed to examine the application of ethanolic extract of the root bark of Berberis vulgaris L. for treatment of mice infected with cutaneous leishmaniasis. At first, 40 BALB/c mice were infected to Leishmania major promastigotes and were divided in two groups A and B. Then, each of A and B groups were divided to two subgroups. Mice from subgroup A1 were treated with 10% root bark alcoholic extract, and mice from subgroup A2 were treated with only alcohol (control). Mice from subgroup B1 were treated with 20% root bark alcoholic extract, and mice from subgroup B2 were treated with only alcohol (control). The 90% recovery was found in the mice treated with 20% root bark extract, and 55% recovery was found with 10% root bark extract, but in the control group, 0% recovery was found. The results of our study showed that the lotion of root bark extract has good suppression effects on parasites. Therefore, it might be a pro for developing new antileishmanial drugs.

In vitro and in vivo efficacy of ether lipid edelfosine against Leishmania spp. and SbV-resistant parasites

Background

The leishmaniases are a complex of neglected tropical diseases caused by more than 20 Leishmania parasite species, for which available therapeutic arsenal is scarce and unsatisfactory. Pentavalent antimonials (SbV) are currently the first-line pharmacologic therapy for leishmaniasis worldwide, but resistance to these compounds is increasingly reported. Alkyl-lysophospoholipid analogs (ALPs) constitute a family of compounds with antileishmanial activity, and one of its members, miltefosine, has been approved as the first oral treatment for visceral and cutaneous leishmaniasis. However, its clinical use can be challenged by less impressive efficiency in patients infected with some Leishmania species, including L. braziliensis and L. mexicana, and by proneness to develop drug resistance in vitro.

Methodology/Principal Findings

We found that ALPs ranked edelfosine>perifosine>miltefosine>erucylphosphocholine for their antileishmanial activity and capacity to promote apoptosis-like parasitic cell death in promastigote and amastigote forms of distinct Leishmania spp., as assessed by proliferation and flow cytometry assays. Effective antileishmanial ALP concentrations were dependent on both the parasite species and their development stage. Edelfosine accumulated in and killed intracellular Leishmania parasites within macrophages. In vivo antileishmanial activity was demonstrated following oral treatment with edelfosine of mice and hamsters infected with L. major, L. panamensis or L. braziliensis, without any significant side-effect. Edelfosine also killed SbV-resistant Leishmania parasites in in vitro and in vivo assays, and required longer incubation times than miltefosine to generate drug resistance.

Conclusions/Significance

Our data reveal that edelfosine is the most potent ALP in killing different Leishmania spp., and it is less prone to lead to drug resistance development than miltefosine. Edelfosine is effective in killing Leishmania in culture and within macrophages, as well as in animal models infected with different Leishmania spp. and SbV-resistant parasites. Our results indicate that edelfosine is a promising orally administered antileishmanial drug for clinical evaluation.

Leishmaniasis represents a major international health problem, has a high morbidity and mortality rate, and is classified as an emerging and uncontrolled disease by the World Health Organization. The migration of population from endemic to nonendemic areas, and tourist activities in endemic regions are spreading the disease to new areas. Unfortunately, treatment of leishmaniasis is far from satisfactory, with only a few drugs available that show significant side-effects. Here, we show in vitro and in vivo evidence for the antileishmanial activity of the ether phospholipid edelfosine, being effective against a wide number of Leishmania spp. causing cutaneous, mucocutaneous and visceral leishmaniasis. Our experimental mouse and hamster models demonstrated not only a significant antileishmanial activity of edelfosine oral administration against different wild-type Leishmania spp., but also against parasites resistant to pentavalent antimonials, which constitute the first line of treatment worldwide. In addition, edelfosine exerted a higher antileishmanial activity and a lower proneness to generate drug resistance than miltefosine, the first drug against leishmaniasis that can be administered orally. These data, together with our previous findings, showing an anti-inflammatory action and a very low toxicity profile, suggest that edelfosine is a promising orally administered drug for leishmaniasis, thus warranting clinical evaluation.