Leishmaniasis is a complex of parasitic protozoan diseases caused by more than 20 different species of parasites from Leishmania genus. Conventional treatments are high costly, and promote a sort of side effects. Besides, protozoan resistance to treatments has been reported. Natural products have been investigated as a source of new therapeutic alternatives, not only acting directly against the parasite but also being able to synergistically act on the host immune system in order to control parasitemia. Gallic acid (GA) and ellagic acid (EA) are plant-derived phenolic compounds which are able to induce antiinflammatory, gastroprotective, and anticarcinogenic activities. Therefore, the antileishmania, cytotoxic, and immunomodulatory activities of GA and EA were evaluated in this study. Both GA and EA were able to inhibit the growth of Leishmania major promastigotes (effective concentration (EC) values 16.4 and 9.8 μg/mL, respectively). The cytotoxicity against BALB/c murine macrophages for GA and EA was also assessed (CC values 126.6 and 23.8 μg/mL, respectively). Interestingly, GA and EA also significantly reduced the infection and infectivity of macrophages infected by L. major (EC values 5.0 and 0.9 μg/mL, respectively), with selectivity index higher than 20. Furthermore, both GA and EA induced high immunomodulatory activity evidenced by the increase of phagocytic capability, lysosomal volume, nitrite release, and intracellular calcium [Ca] in macrophages. Further investigations are reinforced in order to evaluate the therapeutic effects of GA and EA in in vivo experimental infection model of leishmaniasis.

Gold (Au0) and silver (Ag0) nanoparticles were synthesized using tannic acid (TA) as both reducing and stabilizer. Nanoparticles formation, stability, and interaction with TA were compared to citrate-coated nanoparticles and monitored by UV-Vis, zeta potential, and transmission electron microscopy. TA coating resulted in a red-shift and broadening of bands compared to citrate-coated nanoparticles (NPs-Cit). AgNPs-TA and AuNPs-TA are negatively charged with mean surface charge of -29.4 mV and -29.6 mV, respectively. TEM images showed polydispersety of AuNPs-TA (6-42 nm) and aggregation of AgNPs-TA (12-71 nm). In vitro assays of Leishmania amazonensis promastigotes showed an increment of antileishmanial activity for AgNPs-TA in relation to AgNPs-Cit, while AuNPs-TA and AuNPs-Cit did not affect the protozoas at tested concentrations. CC50 value for AgNPs-TA suggested that TA attenuates nanosilver toxicity comparatively to its precursor (Ag+). This investigation can contribute to the development of new, green, and fast produced drugs aiming at leishmaniasis treatment.

Silver nanoparticles have been studied as an alternative for treatment of microbial infections and leishmaniasis, without promoting induction of microbial or parasite resistance. In this study, chitosan-based silver nanoparticles were synthesized from silver nitrate (AgNO 3), sodium borohydride as a reducing agent, and the biopolymer chitosan as a capping agent. The chitosanbased silver nanoparticles were characterized by ultraviolet-visible, Fourier transform infrared, dynamic light scattering, zeta potential, atomic force microscopy, and transmission electron microscope. The antibacterial assay was performed by determination of the minimum inhibitory

Myracrodruon urundeuva (Engl.) Fr. All., commonly known as "aroeira-do-sertão", is a medicinal plant from Anacardiaceae family. In this study, the chemical composition of M. urundeuva essential oil (MuEO) was evaluated by gas chromatography-mass spectrometry (GC-MS), as well as its anti-Leishmania potential, cytotoxicity, and macrophage activation capability as possible antiprotozoal mechanism of action were assessed. Fourteen compounds were identified, which constituted 94.87% of total oil composition. The most abundant components were monoterpenes (80.35%), with β-myrcene (42.46%), α-myrcene (37.23%), and caryophyllene (4.28%) as the major constituents. The MuEO inhibited the growth of promastigotes (IC 205 ± 13.4 μg mL), axenic amastigotes (IC 104.5 ± 11.82 μg mL) and decreased percentage of macrophage infection and number of amastigotes per macrophage (IC of 44.5 ± 4.37 μg⋅mL), suggesting significant anti-Leishmania activity. The cytotoxicity of MuEO was assessed by MTT test in Balb/c murine macrophages and by human erythrocytes lysis assay and low cytotoxicity for these cells was observed. The CC value against macrophages were 550 ± 29.21 μg mL, while cytotoxicity for erythrocytes was around 20% at the highest concentration assessed, with HC > 800 μg mL. While MuEO-induced anti-Leishmania activity is not mediated by increases in both lysosomal activity and nitric oxide production in macrophages, the results suggest the antiamastigote activity is associated with an immunomodulatory activity of macrophages due to an increase of phagocytic capability induced by MuEO. Thus, MuEO presented significant activity against Leishmania amazonensis, probably modulating the activation of macrophages, with low cytotoxicity to murine macrophages and human erythrocytes.

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