Leishmaniasis is a neglected tropical disease that demands for new therapeutic strategies due to adverse side effects and resistance development promoted by current drugs. Nitric oxide (NO)-donors ...show potential to kill Leishmania spp. but their use is limited because of their instability. In this work, we synthesize, characterize, and encapsulate S-nitroso-mercaptosuccinic acid into chitosan nanoparticles (NONPs) and investigate their activity on promastigotes and intracellular amastigotes of Leishmania (Leishmania) amazonensis. Cytotoxicity on macrophages was also evaluated. We verified that NONPs reduced both forms of the parasite in a single treatment. We also noticed reduction of parasitophorous vacuoles as an evidence of inhibition of parasite growth and resolution of infection. No substantial cytotoxicity was detected on macrophages. NONPs were able to provide a sustained parasite killing for both L. (L.) amazonensis infective stages with no toxicity on macrophages, representing a promising nanoplatform for cutaneous leishmaniasis.
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•We successfully synthesized and characterized NO-loaded chitosan nanoparticles.•NONPs were able to efficiently inactivate Leishmania (L.) amazonensis promastigotes.•NONPs were not toxic to macrophages.•NONPs inactivated intracellular amastigotes following one single application.•NONPs promoted parasitophorous vacuole reduction indicating infection resolution.
Cutaneous leishmaniasis (CL) is a neglected disease that promotes destructive lesions. Difficulties in treatment are related to accessibility of drugs, resistance and toxicity. Antimicrobial ...photodynamic therapy (APDT) has been emerging as a promising treatment for CL. In this work, we evaluated methylene blue (MB)‐mediated APDT (MB‐APDT) on Leishmania amazonensis in vitro and in vivo by bioluminescence technique. In vitro, MB‐APDT was performed using a red LED (λ = 660 ± 11 nm, 100 mW cm−2) and MB (100 µm) at different light doses. In vivo, mice were infected and 4 weeks later, randomly divided into three groups: control, APDT 1 (single session) and APDT 2 (two sessions of MB‐APDT). MB was used at 100 µm and energy dose was established at 150 J cm−2. Parasite burden, lesion size and pain were evaluated weekly for 4 weeks. In vitro, lethal dose for 90% parasite inactivation was achieved at 48.8 J cm−2. In vivo, although APDT 1 and APDT 2 groups have showed similar parasite burden after 4 weeks, two sessions were clinically better, especially considering the inflammatory process associated to CL. Our findings reinforce MB‐APDT as a cost‐effective treatment to combat CL.
Cutaneous leishmaniasis (CL) is a neglected disease that causes ulcerated lesions. Current treatments are limited due to high cost, resistance and toxicity. Photodynamic therapy has been put forward as an alternative treatment for CL. Here, we investigated methylene blue‐mediated photodynamic therapy (MB‐APDT) on Leishmania (L.) amazonensis in vitro using a red LED at different fluences. In vivo, we compared one and two MB‐APDT sessions at L. amazonensis‐induced CL in mice. Disease progress was evaluated by bioluminescence, lesion size and pain score. Our results indicate that MB‐APDT could be a cost‐effective strategy to apply in public health.
The dioctadecyldimethylammonium bromide (DODAB) is a double-chained cationic lipid with potent bactericide and fungistatic activities; however, its toxicity on protozoan parasites is still unknown. ...Here, we show the antileishmanial activity of DODAB nano-sized cationic bilayer fragments on stationary-phase promastigotes and amastigotes of
, the causative agent of cutaneous leishmaniasis. Upon treatment with DODAB, we analyzed the parasite surface zeta-potential, parasite viability, cellular structural modifications, and intracellular proliferation. The DODAB cytotoxic effect was dose-dependent, with a median effective concentration (EC
) of 25 µM for both life-cycle stages, comparable to the reported data for bacteria and fungi. The treatment with DODAB changed the membrane zeta-potential from negative to positive, compromised the parasite's morphology, affected the cell size regulation, caused a loss of intracellular organelles, and probably dysregulated the plasma membrane permeability without membrane disruption. Moreover, the parasites that survived after treatment induced small parasitophorous vacuoles and failed to proliferate inside macrophages. In conclusion, DODAB displayed antileishmanial activity, and it remains to be elucidated how DODAB acts on the protozoan membrane. Understanding this mechanism can provide insights into the development of new parasite-control strategies.
Abstract
Acanthamoeba causes infections in humans and other animals and it is important to develop treatment therapies. Jatropha curcas, Jatropha gossypifolia and Euphorbia milii plant extracts ...synthesized stable silver nanoparticles (AgNPs) that were relatively stable. Amoebicidal activity of J. gossypifolia, J. curcas and E. milii leaf extracts showed little effect on viability of Acanthamoeba castellanii trophozoites. Plant-synthesized AgNPs showed higher amoebicidal activity. AgNPs synthesized by J. gossypifolia extract were able to kill 74–27% of the trophozoites at concentrations of 25–1.56 μg mL−1. AgNPs were nontoxic at minimum inhibitory concentration with peripheral blood mononuclear cells. These results suggest biologically synthesized nanoparticles as an alternative candidate for treatment of Acanthamoeba infections.
Virulent protozoans named Leishmania in tropical and subtropical areas produce devastating diseases by exploiting host immune responses. Amastigotes of Leishmania amazonensis stimulate macrophages to ...express CD200, an immunomodulatory ligand, which binds to its cognate receptor (CD200R) and inhibits the inducible nitric oxide synthase and nitric oxide (iNOS/NO) signaling pathways, thereby promoting intracellular survival. However, the mechanisms underlying CD200 induction in macrophages remain largely unknown. Here, we show that phagocytosis-mediated internalization of L. amazonensis amastigotes following activation of endosomal TLR9/MyD88/TRIF signaling is critical for inducing CD200 in infected macrophages. We also demonstrate that Leishmania microvesicles containing DNA fragments activate TLR9-dependent CD200 expression, which inhibits the iNOS/NO pathway and modulates the course of L. amazonensis infection in vivo. These findings demonstrate that Leishmania exploits TLR-signaling pathways not only to inhibit macrophage microbicidal function, but also to evade host systemic immune responses, which has many implications in the severity of the disease.
Microbial extracts continue to be a productive source of new molecules with biotechnological importance. Fungi of the genus Penicillium are known to produce biologically active secondary metabolites. ...The goal of this work is verify the production of antimicrobial metabolites by Penicillium chrysogenum IFL1 using agro-industrial residues. P. chrysogenum IFL1 produced active metabolites growing on the agro-industrial residues, grape waste and cheese whey. The 7-day cultures showed antimicrobial activities against bacteria, fungi and amoebae. The filtrate of the cheese whey culture inhibited the growth of the bacteria Staphylococcus aureus, Bacillus cereus and Pseudomonas aeruginosa, the fungus Fusarium oxysporum and the amoeba Acanthamoeba polyphaga. Due to the greater antimicrobial activity of the cheese whey culture, a footprinting profile was carried out using the ESI-MS and ESI-MS/MS techniques. The presence of penicillin G and other metabolites that have antimicrobial activity such as penicillin V and rugulosin can be suggested. P. chrysogenum IFL1 was able to produce a wide variety of antimicrobial compounds on agro-industrial residues, which makes the process ecologically friendly.
The identification of new compounds is urgent to develop safe and efficacious candidates for leishmaniasis treatment, especially from natural products as a potential source of active molecules ...against neglected tropical parasite diseases. Inspired by the efficacious quinoline alkaloid microbial effects, we have previously reported the synthesis and biological activity of 2‐phenylquinoline‐4‐carboxylic acids and poly‐substituted quinolines against parasites. In this work, a series of eighteen 2‐styryl‐4‐quinolinecarboxylic acids were synthesized under microwave irradiation settings obtaining from good to excellent yields (60%‐90%), shorter reaction times (2 minutes), and eco‐friendly experimental conditions. All these products were evaluated against infective forms of Leishmania (Leishmania) amazonensis, such as promastigotes and intracellular amastigotes, based on cytotoxicity assays, including host macrophage infection assays. Compounds 4 and 5 possessing a 2‐chloro or 4‐chlorostyryl moiety, respectively, were considered the most promising antileishmanial agents due to the parasite killing effect in intracellular forms inside infected macrophages. Thus, our results revealed that the 2‐styryl‐4‐quinolinecarboxylic acid backbone structure was essential for the activity against intracellular pathogens like L. (L.) amazonensis.
The leishmaniases are a group of diseases caused by protozoan parasites from Leishmania species. Effectiveness therapies for cutaneous leishmaniasis (CL), the most common form, are still needed to be ...developed since the available drugs such as meglumine antimoniate (MA) present severe adverse reactions. Here, we develop and characterize maltodextrin polymeric colloidal nanocarriers containing MA (PCN-MA) for topical CL treatment. PCN-MA is composed of 5 to 8% maltodextrin, 0.3% NaCl, 1% MA in 21% of water as aqueous-internal phase, containing or no 3% Kolliphor® P-188, and 10% SF1540 dispersed in a silicone-based external phase. It formed a colloidal system dispersed in silicone with high encapsulation efficiency (87% to 92%) and composite spherical-shaped particles with the smooth and regular surface within the nanosized scale, which was confirmed by scanning electron microscopy (SEM) and dynamic light scattering (DLS) analysis. Ex vivo cutaneous retention studies using pig ears skin on Franz diffusion cells revealed that the MA cutaneous retention is improved when delivered by PCN. Topical PCN-MA evaluation in murine leishmaniasis model showed similar efficacy than the intraperitoneal injection of the reference medicine (Glucantime®) regarding parasite titer reduction and superior healing activity in terms of collagen area deposition. Our results suggest that this sugar-based PCN is a promising agent for topical delivery of meglumine antimoniate.
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