Amastigote Forms Research Articles

Susceptibility of Leishmania amazonensis Axenic Amastigotes to the Calpain Inhibitor MDL28170

Leishmaniasis encompasses a group of neglected diseases caused by flagellated protozoa belonging to the Leishmania genus, associated with high morbidity and mortality. The search for compounds with anti-Leishmania activity that exhibit lower toxicity and can overcome the emergence of resistant strains remains a significant goal. In this context, the calpain inhibitor MDL28170 has previously demonstrated deleterious effects against promastigote forms of Leishmania amazonensis, which led us to investigate its role on axenic amastigote forms. The calpain inhibitor MDL28170 was able to decrease the viability of amastigotes in a typically dose-dependent manner. The treatment with the IC50 dose (13.5 μM) for 72 h led to significant amastigote lysis and increased cell-to-cell aggregation. Ultrastructural analysis revealed several cellular alterations, including disruption of the trans-Golgi network and the formation of autophagosomes when treated with MDL28170 at ½ × IC50 dose. Additionally, mitochondrial swelling and the formation of concentric membranous structures inside the mitochondrion were observed after incubation with the IC50 dose. These results reinforce the potential application of the calpain inhibitor MDL28170 against L. amazonensis, highlighting its effectiveness and possible mechanism of action against the parasite.

Targeting Leishmaniasis with Nitrovinyl Derivatives: Their Synthesis, In Vitro Assessment, and Computational Exploration.

Leishmaniasis is an affliction caused by the protozoan parasites of the Leishmania genus. This disease impacts a substantial global populace, exceeding one million individuals, leading to disability-adjusted life years and fatalities, particularly within tropical regions. At present, the existing drug therapies have not attained a degree of efficacy that can be unequivocally classified as genuinely triumphant. In this context, the conception of novel compounds possessing the capacity to impede the parasite's life cycle at various stages holds considerable significance. In this research endeavor, an exploration was undertaken involving the design and synthesis of nineteen derivatives incorporating the nitrovinyl pharmacophore. The subsequent evaluation of their impacts on L. major was conducted through a combination of in vitro (amastigote and promastigote inhibition) and in silico (molecular docking) investigations. All of the compounds were synthesized and purified with good yields. In the amastigote inhibition assay, compounds 10, 15, and 18 showed better inhibitory effects than the standard drug meglumine antimonate (MA). Regarding the synergistic impact of synthesized compounds and MA together, all outcomes were significantly better than those of monotherapy of each in amastigote and macrophage forms. In the promastigote assay, compounds 2, 8, 12, 15, 16, 17, and 19 demonstrated superior inhibitory effects compared to MA. Moreover, compounds 4, 12, and 15 showed the best synergies with MA in inhibiting amastigotes. According to docking scores, 1XTP (a SAM-dependent methyltransferase) and 4G5D (Prostaglandin F synthase) receptors were found to be the most probable targets in their mechanism of action. In vitro evaluations and computational analyses strongly suggest that these compounds could be effective against both L. major amastigotes and promastigotes. Additionally, they exhibited notable synergistic interactions with MA against both living forms of the parasite.

Biological properties and in silico studies of thiazolopyrimidine derivatives active against visceral and cutaneous Leishmania spp. amastigote forms

Visceral leishmaniasis, the most severe form of the disease, is caused by L. donovani and L. infantum parasites; cutaneous leishmaniasis is the most common endemic form of leishmaniasis and mainly caused by L. tropica and L. major. We have previously described a series of thiazolopyrimidine derivatives and reported their antipromastigote activities against various parasites. In this study, we also investigated their activities against L. donovani and L. major axenic amastigotes, intramacrophage amastigotes and cytotoxicity on macrophages to assess selectivity. As a result, five of the compounds tested showed no cytotoxicity on the macrophage cell line; their anti-amastigote activity was close to the positive control, miltefosine. These results confirm the antileishmanial activity of the thiazolopyrimidine scaffold and demonstrate that this may be a starting point for the generation of new lead compounds for treating visceral leishmaniasis and cutaneous leishmaniasis. To elucidate the mechanism of action, we also performed several ligand- and structure-based in silico studies.

Hit-to-lead optimization of 4,5-dihydrofuran-3-sulfonyl scaffold against Leishmania amazonensis. Effect of an aliphatic moiety

In line with our objective of designing new antileishmanial compounds for oral use, we report the synthesis and biological evaluation in vitro of original 4,5-dihydrofuran derivatives bearing an amidoxime group. Previous optimization focused on position 3 of the dihydrofuran ring involving aromatic fragments, resulting in the identification of the compound (HIT) 4-(5-benzyl-3-((4-fluorophenyl)sulfonyl)-5-methyl-4,5-dihydrofuran-2-yl)-N′-hydroxybenzimidamide (IC50 = 5.4 ± 1.0 μM, L. amazonensis promastigote, IC50 = 7.9 ± 1.1 μM, L. amazonensis intracellular amastigote). In the present work, position 3 was substituted with an aliphatic moiety. This modification was guided by a ligand-based approach, given the unknown biological target or mechanism of action for this compound. The 4,5-dihydrofuran derivatives were synthesized using microwave-assisted manganese (III) acetate-based oxidative cyclization of linear β-keto-carboxylic and β-keto-sulfone substrates, overcoming synthetic challenges to obtain aliphatic derivatives of 4,5-dihydrofuran-3-carboxamides. Finally, an unexpected and interesting biological activity with the 4,5-dihydrofuran-3-carboxylate (IC50 < 5 μM) against the amastigote form is discussed.

Design and Synthesis of Benzimidazole Carboxamide Cysteine Protease Inhibitors as Promising Anti-leishmanial Agents.

More than 20 protozoan species of Leishmania are responsible for causing Leishmaniasis, an infection spread by blood-feeding phlebotomine sandflies. A narrow pool of drugs is currently available rendering the current drug stratagem to treat this infection . Development of novel, less toxic, and more effective regimens is thus a need of the hour. Design and synthesis of benzo[d]imidazole carboxamides as agents to combat Leishmaniasis are also required. 14 benzo[d]imidazole carboxamides were synthesized and gauged against L. donovani promastigotes and intramacrophage amastigote forms. All of the tested compounds exhibited significant anti-promastigote properties with IC50 well below 10 uM. Compounds 4a, 4b, and 4d, showing the highest anti-parasitic activity against promastigote forms (IC50 0.91- 1.33 μM), were also found to be associated with better anti-leishmanial potential (IC50 0.78- 1.67 μM) against the intramacrophage amastigotes comparable to Amphotericin-B (0.13 μM), a drug used for Leishmaniasis. Compound (4a), namely N-(2-(trifluoromethyl)-1Hbenzo[ d]imidazol-5-yl)benzo[d][1,3]-5-carboxamide-dioxole, was found to be most potent against L. donovani amastigotes among all the tested compounds, and demonstrated better antileishmanial properties (IC50 0.78 μM) when compared to the standard. Compound 4a was also assessed for its toxicity profile against THP-1 human monocytic cells. To establish the molecular target(s) in silico, molecular docking studies were performed against cysteine protease, a putative virulence factor of Leishmania parasites, and nucleoside diphosphate kinase, an enzyme with a critical role in nucleotide recycling, also associated with resistance in Leishmania strains. Compound 4a showed better binding affinity than the standard to these targets; furthermore, the molecular dynamic simulation studies further affirmed the stability of compound 4a, within the active site of the targets. In vitro, cysteine protease inhibitory activity (IC50 8.53 μM) using Bz-Arg-AMC hydrochloride fluorogenic peptide substrate established the promising potential of 4a as a cysteine protease inhibitor. Computational ADMET analysis indicated appropriate pharmacokinetic profile and physicochemical characteristics for all members of the synthesized library. Both in vitro and in silico studies indicate that the synthesized imidazole carboxamides can act as potent hits and that N-(2-(trifluoromethyl)-1H-benzo[d]imidazol-5- yl)benzo[d][1,3]-5-carboxamide-dioxole 4a can be an effective hit molecule which can be further developed into potent lead molecule (s) to fight Leishmania donovani.

Efficacy of Diterpene Polyalthic Acid Combined with Amphotericin B against Leishmania amazonensis In Vitro.

Background/Objectives: Leishmaniasis, a neglected disease caused by Leishmania spp. including L. amazonensis, urgently requires new treatments. Polyalthic acid (PA), a natural diterpene from Copaifera spp., has previously demonstrated significant antiparasitic potential. This study evaluated the leishmanicidal effects of polyalthic acid (PA), alone and with amphotericin B (AmpB), on L. amazonensis promastigote and amastigote forms. Results: PA showed significant activity against promastigotes, with 50% effective concentration (EC50) values of 2.01 μM at 24 h and an EC50 of 3.22 μM against amastigotes after 48 h. The PA and AmpB combination exhibited a synergistic effect on both forms without inducing cytotoxicity or hemolysis. Morphological changes in promastigotes, including vacuole formation and cell rounding, were more pronounced with the combination. Conclusions: These findings suggest that PA and AmpB together could form a promising new treatment strategy against Leishmania infections, offering enhanced efficacy without added toxicity.

Visceral leishmaniasis complicated with hemophagocytic lymphohistiocytosis and resistant to amphotericin B: a case report

IntroductionHemophagocytic lymphohistiocytosis characterized by hemophagocytosis leading to uncontrolled inflammation; the most common etiology in secondary cases of hemophagocytic lymphohistiocytosis is viral infections, especially Epstein–Barr virus. Visceral leishmaniasis is a vectorborne protozoal disease caused by Leishmania donovani complex. It is common in tropical and subtropical regions, with 50,000–90,000 new cases annually.Case presentationA 15-month-old Arab female was admitted to our hospital with 15 days of fever and decreased weight. On clinical examination, she had a markedly enlarged liver and spleen that were palpable 4 cm and 6 cm below the costal margin, respectively. The peripheral blood smear showed hypochromic microcytic anemia, poikilocytosis, reactive lymphocytosis, and mild thrombocytopenia. Bone marrow aspiration did not show malignancy or any other pathological findings. The patient was put on antibiotic therapy without improvement. Repeated bone marrow aspiration showed erythrophagocytosis; intracellular small round organisms looked like the amastigote form of Leishmania (Donovan bodies) with no evidence of malignancies. Her lab values showed ferritin greater than 500 ug/L, pancytopenia, and hypertriglyceridemia. The patient was diagnosed with hemophagocytic lymphohistiocytosis secondary to visceral leishmaniasis.ConclusionHemophagocytic lymphohistiocytosis secondary to visceral leishmaniasis is an extensively rare phenomenon in the medical literature that causes challenges in diagnosis and management. Steroids should be used wisely to not cover the symptoms of infections or malignancy, and amphotericin B resistance should be kept in mind in unresponsive Leishmania cases.

Dioclea violacea lectin has potent in vitro leishmanicidal activity against Leishmania infantum via carbohydrate recognition domain

Despite promising advancements in leishmaniasis treatment, existing therapies often face limitations and significant side effects, stimulating the search for novel therapeutic alternatives. In this context, lectins, such as DVL extracted from Dioclea violacea seeds, have emerged as potential candidates due to their diverse biological activities. This study represents the first investigation of the leishmanicidal potential of DVL in vitro against Leishmania infantum. Our results demonstrate that DVL exhibits a leishmanicidal effect (IC50/24 h = 49.37 μg/mL or 2 μM), binding to glycans on L. infantum. Fluorescence assays revealed that DVL can induce the production of reactive oxygen species (ROS) and cause damage to the parasite's membrane. DVL demonstrated a modulating effect when combined with amphotericin B and glucantime, enhancing the activity of these drugs by 40 % and 80 %, respectively. It also showed no cytotoxicity in Raw 264.7 cells and was able to override the toxic effect of amphotericin B on cells and reduce the survival rate of macrophages infected with amastigote forms, as well as their percentage of infection by 31 %. Therefore, DVL shows promise as a treatment for visceral leishmaniasis caused by L. infantum. Our findings provide valuable insights for future therapeutic development targeting leishmania glycans.

Identification of Novel Antileishmanial Chemotypes By High-Throughput Virtual and In Vitro Screening.

Leishmaniasis is a deadly protozoan parasitic disease and a significant health problem in underdeveloped and developing countries. The global spread of the parasite, coupled with the emergence of drug resistance and severe side effects associated with existing treatments, has necessitated the identification of new and potential drugs. This study aimed to identify promising compounds for the treatment of leishmaniasis by targeting two essential enzymes of Leishmania donovani: trypanothione reductase (Try-R) and trypanothione synthetase (Try-S). High-throughput virtual and in vitro screening of in-house and commercial databases was conducted. A pharmacophore model with seven features was developed and validated using the Guner-Henery method. The pharmacophore-based virtual screening yielded 690 hits, which were further filtered through Lipinski's rule, ADMET analysis, and molecular docking against Try-R and Try-S. Molecular dynamics studies were performed on selected compounds, and in vitro experiments were conducted to evaluate their activity against the promastigote and amastigote forms of L. donovani. The virtual screening and subsequent analysis identified 33 promising compounds. Molecular dynamics studies of two compounds (comp-1 and comp-2) demonstrated stable binding interactions with the target enzymes and high affinity. In vitro experiments revealed that 13 compounds exhibited moderate activity against both the promastigote (IC50, 41 µM-76 µM) and the amastigote (IC50, 44 µM-72 µM) forms of L. donovani. Compounds 1 and 2 showed the highest percent inhibition and the lowest IC50 values. The identified compounds demonstrated significant inhibitory activity against Leishmania donovani and stable interactions with target enzymes. These findings suggest that the compounds could serve as promising leads for developing new treatments for leishmaniasis.

Ballota hirsuta essential oil as a potential multitarget agent against Leishmania parasite: in vitro and in silico studies.

In the present study, we assessed the antioxidant and antileishmanial potential from fresh leaves of Ballota (B.) hirsuta essential oil (EO). The GC-MS analysis of B. hirsuta EO revealed that spathulenol and germacrene D were the main components accounting for 26.03% and 19.64% of the total EO, respectively. B. hirsuta EO possesses moderate antioxidant activity, both in neutralizing DPPH radicals and in inhibiting β-carotene bleaching. In addition, it exhibits both high antileishmanial activity and selectivity towards the promastigote and amastigote forms. Specifically, B. hirsuta EO showed an IC50 value of 20.78µg/mL and 23.62µg/mL, against the promastigote and amastigote forms of L. infantum, respectively. It also demonstrated an IC50 value of 22.39 and 25.76µg/mL, against the promastigote and amastigote forms of L. major, respectively. However, it exhibited moderate cytotoxicity, with a selectivity index below 10. The investigation of the molecular mechanism of action revealed that B. hirsuta EO inhibited only the sterol pathway, including CYP51 gene expression. Additionally, in silico analysis indicated that the main compounds of B. hirsuta EO, germacrene and spathulenol, exhibited excellent affinity energy against Leishmania enzymes trypanothione reductase (TryR) and trypanothione synthase (TryS). This denotes the potential of these compounds as promising agents to control leishmaniasis.

VL-HIV co-infection with Leishmania containing skin lesions resembling para-kala-azar dermal leishmaniasis.

Leishmaniases are a group of neglected vector-borne infectious diseases that are among the six priority endemic diseases worldwide. Visceral leishmaniasis (VL) is the most severe clinical manifestation, characterized by systemic and chronic visceral involvement and high mortality in immunosuppressed and untreated patients. VL can be complicated into post-kala-azar dermal leishmaniasis (PKDL), and when dermatologic disorders occur simultaneously with active VL, an intermediate clinical form called para-kala-azar dermal leishmaniasis (para-KDL) occurs. This clinical form is of great epidemiological relevance, as humans act as a source of infection for vectorial transmission. In the Americas, Brazil is among the seven countries responsible for more than 90% of VL cases, though reports of PKDL and para-KDL are rare. This paper presents three cases of VL-HIV co-infection with Leishmania-containing skin lesions resembling para-kala-azar dermal leishmaniasis. The cases were investigated by the team from the Infectious Diseases Department of University Hospital (HUMAP/UFMS) in Mato Grosso do Sul, Brazil. The three patients exhibited skin lesions where amastigote forms of L. (L.) infantum were identified. All cases exhibited similar clinical manifestations of para-KDL, including fever, hepatosplenomegaly, pancytopenia, and disseminated skin lesions. The study described the prevalence of comorbidities, the incidence of VL relapse, and the therapeutic regimen in relation to the outcomes. The study underscores the importance of follow-up and secondary prophylaxis in patients with VL, which are essential for the efficacy of the treatment. Furthermore, the study provides insight into the potential epidemiological profile of para-KDL cases in Brazil, which contributes to the development of more efficient clinical management strategies for patients.

Polygonum bistorta Linn. as a green source for synthesis of biocompatible selenium nanoparticles with potent antimicrobial and antioxidant properties.

Here, we report for the first time, green-synthesized selenium nanoparticles (SeNPs) using pharmacologically potent herb of Polygonum bistorta Linn. for multiple biomedical applications. In the study, a facile and an eco-friendly approach is utilized for synthesis of SeNPs using an aqueous roots extract of P. bistorta Linn. followed by extensive characterization via Fourier transform infrared spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Energy Dispersive X-Ray (EDX) analysis. The XRD and FTIR data determine the phase composition and successful capping of plant extract onto the surface of NPs while SEM and TEM micrographic examination reveals the elliptical and spherical morphology of the particles with a mean size of 69 ± 23nm. After comprehensive characterization, the NPs are investigated for antifungal, antibacterial, antileishmanial, antioxidant, and biocompatibility properties. The study reveals that Polygonum bistorta Linn. synthesized SeNPs exhibit significant antibacterial and antifungal activities with Staphylococcus aureus and Fusarium oxysporum inducing the highest zone of inhibition of 14 ± 1.0mm and 20 ± 1.2mm, respectively at the concentration of 40mg/mL. The NPs are also found to have antiparasitic potential against promastigote and amastigote forms of Leishmania tropica. Furthermore, the NPs are discovered to have excellent potential in neutralizing harmful free radicals thus exhibiting considerable antioxidant potential. Most importantly, Polygonum bistorta Linn. synthesized SeNPs showed substantial compatibility against blood cells in vitro studies, which signifies the nontoxic nature of the NPs. The study thus concludes that medicinally important Polygonum bistorta Linn. roots can be utilized as an eco-friendly, sustainable, and green source for the synthesis of pharmacologically potent selenium nanoparticles.

In Vitro and In Silico Evaluation of the Leishmanicidal and Trypanocidal Activities of Lignan Methylpiperitol Isolated from Persea Fulva.

Neglected Tropical Diseases are a significant concern as they encompass various infections caused by pathogens prevalent in tropical regions. The limited and often highly toxic treatment options for these diseases necessitate the exploration of new therapeutic candidates. In the present study, the lignan methylpiperitol was isolated after several chromatographic steps from Persea fulva L. E. Koop (Lauraceae) and its leishmanicidal and trypanocidal activities were evaluated using in vitro and in silico approaches. The chemical structure of methylpiperitol was defined by NMR and MS spectral data analysis. The antiprotozoal activity of methylpiperitol was determined in vitro and indicated potency against trypomastigote forms of Trypanosoma cruzi (EC50 of 4.5±1.1 mM) and amastigote forms of Leishmania infantum (EC50 of 4.1±0.5 mM), with no mammalian cytotoxicity against NCTC cells (CC50>200 mM). Molecular docking studies were conducted using six T. cruzi and four Leishmania. The results indicate that for the molecular target hypoxanthine phosphoribosyl transferase in T. cruzi and piteridine reductase 1 of L. infatum, the methylpiperitol obtained better results than the crystallographic ligand. Therefore, the lignan methylpiperitol, isolated from P. fulva holds potential for the development of new prototypes for the treatment of Neglected Tropical Diseases, especially leishmaniasis.

Encapsulation of Citrus sinensis essential oil and R-limonene in lipid nanocarriers: A potential strategy for the treatment of leishmaniasis

Leishmaniases, a group of neglected tropical diseases caused by an intracellular parasite of the genus Leishmania, have significant impacts on global health. Current treatment options are limited due to drug resistance, toxicity, and high cost. This study aimed to develop nanostructured lipid carriers (NLCs) for delivering Citrus sinensis essential oil (CSEO) and its main constituent, R-limonene, against leishmaniasis. The influence of surface-modified NLCs using chitosan was also examined. The NLCs were prepared using a warm microemulsion method, and surface modification with chitosan was achieved through electrostatic interaction. These nanocarriers were characterized by differential scanning calorimetry (DSC), X-ray diffraction (XRD), transmission electron microscopy, and dynamic light scattering (DLS). In vitro cytotoxicity was assessed in L929 and RAW 264.7 cells, and leishmanicidal activity was evaluated against promastigote and amastigote forms. The NLCs were spherical, with particle sizes ranging from 97.9 nm to 111.3 nm. Chitosan-coated NLCs had a positive surface charge, with zeta potential values ranging from 45.8 mV to 59.0 mV. Exposure of L929 cells to NLCs resulted in over 70 % cell viability. Conversely, surface modification significantly reduced the viability of promastigotes (93 %) compared to free compounds. Moreover, chitosan-coated NLCs presented a better IC50 against the amastigote forms than uncoated NLCs. Taken together, these findings demonstrate the feasibility of using NLCs to overcome the limitations of current leishmaniasis treatments, warranting further research.

Unlocking the therapeutic potential of Nigella sativa extract: phytochemical analysis and revealing antimicrobial and antioxidant marvels

The growing global threat of antimicrobial resistance endangers both human and animal life, necessitating the urgent discovery of novel antimicrobial solutions. Medicinal plants hold promise as sources of potential antimicrobial compounds. In this study, we investigated the phytochemical constituents and microbicidal capabilities of the ethanolic extract from Nigella sativa (black seed). Gas chromatography analysis (GC) identified 11 compounds, among them thymoquinone, and thymol, contributing to antimicrobial and antioxidant properties. Antimicrobial assays demonstrated notable inhibition zones against broad spectra of bacteria, including Pseudomonas aeruginosa, Escherichia coli, Salmonella typhi, Staphylococcus aureus, Enterobacter, and Bacillus subtilis, along with potent antifungal activity against Aspergillus niger, Penicillium, and Candida albicans. Notably, when combined with antibiotics, the extract displayed exceptional synergistic antimicrobial efficacy. The black seed extract demonstrated membrane-damaging activity and disrupted virulence factors that protect microbes from antimicrobial agents, including the formation of bacterial biofilm and protease secretion. Thymoquinone, the primary active constituent of the extract, exhibited similar antimicrobial and ant virulence properties. In silico analysis targeting key regulators of quorum sensing and biofilm formation in P. aeruginosa, such as RhlG, LasR, and PqsR, showed a remarkable affinity of thymol and thymoquinone for these targets. Moreover, the N. sativa extract exhibited dose-dependent cytotoxicity against both the promastigote and amastigote forms of Leishmania tropica parasites, hinting at potential antiparasitic activity. In addition to its antimicrobial properties, the extract displayed potential antioxidant activity at a concentration of 400 μg/mL.

Antileishmanial, Immune Modulation and Apoptosis Induction by Astragalus ecbatanus Extract Against Leishmania tropica

Background: Due to the unique properties of Astragalus in treating diseases and strengthening the immune system, this study aimed to investigate, for the first time, the immune modulation and apoptosis induction by Astragalus ecbatanus extract against Leishmania tropica. Methods: The study assessed the in vitro efficacy of the Astragalus ecbatanus extract against both the promastigote and amastigote stages of L. tropica (MHOM/AF/88/KK27). Additionally, the effects of the extract on inducing nitric oxide (NO) release and its cytotoxicity on human macrophage cells were determined by calculating the 50% cytotoxic concentrations (CC50). The study also evaluated the Caspase-3-like activity in extract-treated parasites and conducted quantitative real-time PCR to assess the expression of genes associated with T lymphocytes. Results: Our study demonstrated that the A. ecbatanus extract significantly (P &lt; 0.001) decreased the viability of both L. tropica promastigote and amastigote forms compared to the negative control. Moreover, the extract exhibited a high selectivity index (&gt; 10), indicating its strong specificity towards intracellular parasites while showing low cytotoxicity to host cells. Our results indicated a dose-dependent upregulation of the expression levels of genes for inducible nitric oxide synthase (iNOS), interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNFα), and interleukin-10 (IL-10) in macrophages after exposure to A. ecbatanus ethyl acetate extract (P &lt; 0.01). In contrast, the gene expression level of IL-10 exhibited a dose-dependent downregulation after exposure to A. ecbatanus ethyl acetate extract. We also found that the THP-1 macrophages exposed to the A. ecbatanus ethyl acetate extract exhibited enhanced production of nitric oxide (P &lt; 0.001). Additionally, the ethyl acetate extract of A. ecbatanus significantly enhanced caspase-3 activation in Leishmania parasites (P &lt; 0.01). Conclusions: The results demonstrated the significant impact of A. ecbatanus ethyl acetate extract on inhibiting and eradicating Leishmania parasites in laboratory settings. While some cellular mechanisms of action were identified, such as immune modulation and apoptosis induction against Leishmania parasites, further investigation is essential to elucidate the specific mechanisms of action and assess the efficacy in animal and human populations.

Antimicrobial activity of nanoparticles based on carboxymethylated cashew gum and epiisopiloturine: In vitro and in silico studies

Epiisopiloturine (EPI) is a compound found in jaborandi leaves with antiparasitic activity, which can be enhanced when incorporated into nanoparticles (NP). Cashew Gum (CG), modified by carboxymethylation, is used to produce polymeric nanomaterials with biological activity. In this study, we investigated the antimicrobial potential of carboxymethylated CG (CCG) NP containing EPI (NPCCGE) and without the alkaloid (NPCCG) against bacteria and parasites of the genus Leishmania. We conducted theoretical studies, carboxymethylated CG, synthesized NP by nanoprecipitation, characterized them, and tested them in vitro. Theoretical studies confirmed the stability of modified carbohydrates and showed that the EPI-4A30 complex had the best interaction energy (−8.47 kcal/mol). CCG was confirmed by FT-IR and presented DSabs of 0.23. NPCCG and NPCCGE had average sizes of 221.94 ± 144.086 nm and 247.36 ± 3.827 nm, respectively, with homogeneous distribution and uniform surfaces. No NP showed antibacterial activity or cytotoxicity to macrophages. NPCCGE demonstrated antileishmanial activity against L. amazonensis, both in promastigote forms (IC50 = 9.52 μg/mL, SI = 42.01) and axenic amastigote forms (EC50 = 6.6 μg/mL, SI = 60.60). The results suggest that nanostructuring EPI in CCG enhances its antileishmanial activity.

Anti-Leishmania effect of icetexanes from Salvia procurrens

Background and purposeLeishmaniasis is a globally prevalent vector-borne disease caused by parasites of the genus Leishmania. The available chemotherapeutic drugs present problems related to efficacy, emergence of parasite resistance, toxicity and high cost, justifying the search for new drugs. Several classes of compounds have demonstrated activity against Leishmania, including icetexane-type diterpenes, previously isolated from Salvia and other Lamiaceae genera. Thus, in this study, compounds of Salvia procurrens were investigated for their leishmanicidal and immunomodulatory activities. MethodsThe exudate of S. procurrens was obtained by rapidly dipping the aerial parts in dichloromethane. The compounds were isolated by column and centrifugal planar chromatography over silica gel. The effects on L. amazonensis growth, survival, membrane integrity, reactive oxygen species (ROS) generation, mitochondrial membrane potential and cytotoxicity of the compounds towards human erythrocytes, peripheral blood mononuclear cells and macrophages were evaluated. The effects on intracellular amastigote forms, nitric oxide (NO) and TNF-α production were also investigated. ResultsThe exudate from the leaves afforded the novel icetexane 7-hydroxyfruticulin A (1) as well as the known demethylisofruticulin A (2), fruticulin A (3) and demethylfruticulin A (4). The compounds (1–4) were tested against promastigotes of L. amazonensis and showed an effective inhibition of the parasite survival (IC50 = 4.08–16.26 μM). In addition, they also induced mitochondrial ROS production, plasma membrane permeability and mitochondrial dysfunction in treated parasites, and presented low cytotoxicity against macrophages. Furthermore, all diterpenes tested reduced the number of parasites inside macrophages, by mechanisms involving TNF-α, NO and ROS. ConclusionThe results suggest the potential of 7-hydroxyfruticulin A (1) as well as the known demethylisofruticulin A (2),fruticulin A (3) and demethylfruticulin A (4) as candidates for use in further studies on the design of anti-leishmanial drugs.

Vaccine Designing Technology against Leishmaniasis: Current Challenges and Implication.

Leishmaniasis, a debilitating disease caused by protozoan parasites of the genus Leishmania and transmitted by the bite of a female sandfly, continues to present significant challenges despite ongoing research and collaboration in vaccine development. The intricate interaction between the parasite's life cycle stages and the host's immunological response, namely the promastigote and amastigote forms, adds complexity to vaccine design. The quest for a potent vaccine against Leishmaniasis demands a comprehensive understanding of the immune mechanisms that confer long-lasting protection, which necessitates extensive research efforts. In this pursuit, innovative approaches such as reverse vaccinology and computer-aided design offer promising avenues for unraveling the intricacies of host-pathogen interactions and identifying effective vaccine candidates. However, numerous obstacles, including limited treatment options, the need for sustained antigenic presence, and the prevalence of co-infections, particularly with HIV, impede progress. Nevertheless, through persistent research endeavours and collaborative initiatives, the goal of developing a highly efficacious vaccine against Leishmaniasis can be achieved, offering hope through the latest Omics data development with immunoinformatics approaches for effective vaccine design for the prevention of this disease.

Activity of pyridyl-pyrazolone derivatives against Trypanosoma cruzi

New affordable drugs are needed for the treatment of infection with the protozoan parasite Trypanosoma cruzi responsible for the Chagas disease (CD). Only two old drugs are currently available, nifurtimox and benznidazole (Bz) but they exhibit unwanted side effects and display a weak activity in the late chronic phase of the disease. In this context, we evaluated the activity of a series of aryl-pyrazolone derivatives against T cruzi, using both bloodstream trypomastigote and intracellular amastigote forms of the parasite. The test compounds originate from a series of anticancer agents targeting the immune checkpoint ligand PD-L1 and bear an analogy with known anti-trypanosomal pyrazolones. A first group of 6 phenyl-pyrazolones was tested, revealing the activity of a single pyridyl-pyrazolone derivative. Then a second group of 8 compounds with a common pyridyl-pyrazolone core was evaluated. The in vitro testing process led to the identification of two non-cytotoxic and highly potent molecules against the intracellular form of T. cruzi, with an activity comparable to Bz. Moreover, one compound revealed an activity largely superior to that of Bz against bloodstream trypomastigotes, while being non-cytotoxic (selectivity index >1000). Unfortunately, the compound showed little activity in vivo, most likely due to its very limited plasma stability. However, the study opens novel perspectives for the design of new anti-trypanosomal products and the mechanism of action of the compounds is discussed.