Leishmaniasis is a group of diseases caused by a protozoa parasite from one of over 20 Leishmania species. Depending on the tissues infected, these diseases are classified as cutaneous, mucocutaneous and visceral leishmaniasis. For the treatment of leishmaniasis refractory to antimony-based drugs, pentamidine (PTM) is a molecule of great interest. However, PTM displays poor bioavailability through oral routes due to its two strongly basic amidine moieties, which restricts its administration by a parenteral route and limits its clinical use. Among various approaches, nanotechnology-based drug delivery systems (nano-DDS) have potential to overcome the challenges associated with PTM oral administration. Here, we present the development of PTM-loaded PLGA nanoparticles (NPs) with a focus on the characterization of their physicochemical properties and potential application as an oral treatment of leishmaniasis. NPs were prepared by a double emulsion methodology. The physicochemical properties were characterized through the mean particle size, polydispersity index (PdI), zeta potential, entrapment efficiency, yield process, drug loading, morphology, in vitro drug release and in vivo pharmacological activity. The PTM-loaded PLGA NPs presented with a size of 263 ± 5 nm (PdI = 0.17 ± 0.02), an almost neutral charge (−3.2 ± 0.8 mV) and an efficiency for PTM entrapment of 91.5%. The release profile, based on PTM dissolution, could be best described by a zero-order model, followed by a drug diffusion profile that fit to the Higuchi model. In addition, in vivo assay showed the efficacy of orally given PTM-loaded PLGA NPs (0.4 mg kg ⁻¹ ) in infected BALB/c mice, with significant reduction of organ weight and parasite load in spleen ( p -value < 0.05). This work successfully reported the oral use of PTM-loaded NPs, with a high potential for the treatment of visceral leishmaniasis, opening a new perspective to utilization of this drug in clinical practice.

Leishmaniasis is the generic denomination to the neglected diseases caused by more than 20 species of protozoa belonging to the genus Leishmania. The toxic and parenteral-delivered pentavalent antimonials remain to be the first-line treatment. However, all the current used drugs have restrictions. The species Aureliana fasciculata (Vell.) Sendtner var. fasciculata is a native Brazilian species parsimoniously studied on a chemical point of view. In this study, the antileishmanial activity of A. fasciculata was evaluated. Among the evaluated samples of the leaves, the dichloromethane partition (AFfDi) showed the more pronounced activity, with IC₅₀ 1.85 µg/ml against promastigotes of L. amazonensis. From AFfDi, two active withanolides were isolated, the Aurelianolides A and B, with IC₅₀ 7.61 μM and 7.94 μM, respectively. The withanolides also proved to be active against the clinically important form, the intracellular amastigote, with IC₅₀ 2.25 μM and 6.43 μM for Aurelianolides A and B, respectively. Furthermore, withanolides showed results for in silico parameters of absorption, distribution, metabolism, excretion, and toxicity (ADMET) similar to miltefosine, the reference drug, and were predicted as good oral drugs, with the advantage of not being hepatotoxic. These results suggest that these compounds can be useful as scaffolds for planning drug design.

Trypanosoma cruzi , the causative agent of Chagas disease, exhibits a complex life cycle with multiple hosts, stages and differentiation steps. We present a complete cell atlas for the T. cruzi life cycle, based on single cell transcriptomes for over 31,000 cells and population-based transcriptomics. The atlas reveals many life cycle associated genes and can be utilised to accurately annotate life cycle stages. It provides detailed insights into cell heterogeneity, including cell-specific repertoires of surface antigens in trypomastigotes, with key implications for immune responses. Enabled by single-cell resolution, we define the transcriptomic changes that occur across the epimastigote to metacyclic trypomastigote differentiation axis. Furthermore, we provide comprehensive UTR annotation, identifying previously unannotated transcripts as well as revealing alternative poly-adenylation and an unanticipated complexity of reverse strand and antisense transcripts. This T. cruzi atlas provides a comprehensive resource and unlocks a range of new avenues for research on this important human pathogen.

Translational studies involving the reuse and association of drugs are approaches that can result in higher success rates in the discovery and development of drugs for serious public health problems, including leishmaniasis. If we consider the number of pathogenic species in relation to therapeutic options, this arsenal is still small, and each drug possesses a disadvantage in terms of toxicity, efficacy, price, or treatment regimen. In the search for new drugs, we performed a drug screening of L. amazonensis promastigotes and intracellular amastigotes of fifty available drugs belonging to several classes according to their pharmacophoric group. Spironolactone, a potassium-sparing diuretic, proved to be the most promising drug candidate. After demonstrating the in vitro antileishmanial activity, we evaluated the efficacy on a murine experimental model with L. amazonensis and L. infantum. The treatment controlled the cutaneous lesion and reduced the parasite burden of L. amazonensis significantly, as effectively as meglumine antimoniate. The treatment of experimental visceral leishmaniasis was effective in reducing the parasite load on the main affected organs (spleen and liver) via high doses of spironolactone. The association between spironolactone and meglumine antimoniate promoted better control of the parasite load in the spleen and liver compared to the group treated with meglumine antimoniate alone. These results reveal a possible benefit of the concomitant use of spironolactone and meglumine antimoniate that should be studied more in depth for the future possibility of repositioning for leishmaniasis co-therapy.

Fifteen polar extracts from leaf, seed, pod, stem, flower and root of Crotalaria spectabilis were prepared using aqueous systems, based on the principles of green chemistry, and showed different protease inhibitor (PI) activities on trypsin, papain, pepsin and the extracellular L. amazonensis serine protease (LSPIII). The most pronounced inhibitory effect on LSPIII was observed in leaf (CS-P), root, stem, flower (CS-FPVPP) and pod (CS-VA) extracts. Crotalaria extracts exhibited low cytotoxicity on macrophages; however, they decreased the viability of L. amazonensis promastigotes and amastigotes, as observed in leaf (CS-AE, CS-P, CS-T and CS-PVPP), seed (CS-ST), flower and root (CS-RA) extracts. CS-P was chosen to study PI and secondary metabolites and a 10-12 kDa protein, analyzed by mass spectrometry, was identified as a serine PI homologous with papaya latex serine PI. Glycosylated flavonoids, such as quercetins, vitexin and tricin were the major secondary metabolites of CS-P. The presence of PIs in C. spectabilis is a new finding, especially in other organs than seeds since PIs have been reported only in seed legumes. Besides, this is the first report of antileishmanial activity of C. spectabilis extracts and the identification of serine polypeptide PI and glycosylated flavonoids from leaf.