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Parenteral administration of amphotericin B-deoxycholate (AmB-DOC) or pentavalent antimonials to cure cutaneous leishmaniasis (CL) results in severe adverse reactions, while topically applied antileishmanial drugs are ineffective despite their good tolerance. This work is aimed to investigate whether poly­(isobutylcyanoacrylate) nanoparticles coated with chitosan (Cs-NPs) could provide intrinsic antileishmanial activity after topical application. In vitro evaluations revealed that nanoparticles were active against the promastigote, axenic amastigote, and intramacrophage forms of Leishmania major. In vivo evaluations after repetitive topical applications on the skin of mice infected with L. major showed that Cs-NPs combined or not with AmB-DOC allowed partial healing of the lesion characterized by histological analyses. The parasitic load of skin specimens collected from mice was significantly reduced compared with that from nontreated mice, as analyzed by quantitative polymerase chain reaction (q-PCR). Ultrastructure characterizations by electron microscopy of L. major promastigotes after incubation with Cs-NPs showed morphological alterations, including aberrant shape and swelling of mitochondria and parasitic vacuoles.

Trichomonas vaginalis motility in biological fluids plays a prominent, but understudied, role in parasite infectivity. In this study, the ability of a thermosensitive hydrogel (pluronic F127) to physically immobilize T. vaginalis was investigated. Blocking parasite motility could prevent its attachment to the mucosa, thus reducing the acquisition of the infection. The trajectory of individual parasites was monitored by multiple particle tracking. Mean square displacement, diffusivity, and velocity were calculated from x, y coordinates during time. Major results are that T. vaginalis exhibited different types of trajectories in a diluted solution composed of lactate buffer similar to “run-and-tumble” motion reported for flagellated bacteria. The fastest T. vaginalis specimen moves with a velocity of 19 μm/s. Observation of T. vaginalis movements showed that the cell body remains rigid during swimming and that the propulsive forces necessary to generate the movement are the result of flagellar beating. Parasite motility was partially slowed down using hydroxyethylcellulose hydrogel, used as a reference for the development of vaginal microbicides, while 100% of T. vaginalis were immobile in F127 hydrogel. Once completed by biological investigations on mice, this report suggests using drug-free formulation composed of F127 as a new strategy to prevent T. vaginalis attachment to the mucosa. The concept will be extended to other flagellated organisms where the motility is driven by cilia and flagella.

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