Selenium-Containing (Hetero)Aryl Hybrids as Potential Antileishmanial Drug Candidates: In Vitro Screening against L. amazonensis

Leishmaniasis remains a significant global health concern, with current treatments relying on outdated drugs associated with high toxicity, lengthy administration, elevated costs, and drug resistance. Consequently, the urgent need for safer and more effective therapeutic options in leishmaniasis treatment persists. Previous research has highlighted selenium compounds as promising candidates for innovative leishmaniasis therapy. In light of this, a library of 10 selenium-containing diverse compounds was designed and evaluated in this study. These compounds included selenium-substituted indole, coumarin, chromone, oxadiazole, imidazo[1,2-a]pyridine, Imidazo[2,1-b]thiazole, and oxazole, among others. These compounds were screened against Leishmania amazonensis promastigotes and intracellular amastigotes, and their cytotoxicity was assessed in peritoneal macrophages, NIH/3T3, and J774A.1 cells. Among the tested compounds, MRK-106 and MRK-108 displayed the highest potency against L. amazonensis promastigotes with reduced cytotoxicity. Notably, MRK-106 and MRK-108 exhibited IC50 values of 3.97 µM and 4.23 µM, respectively, and most of the tested compounds showed low cytotoxicity in host cells (CC50 > 200 µM). Also, compounds MRK-107 and MRK-113 showed activity against intracellular amastigotes (IC50 18.31 and 15.93 µM and SI 12.55 and 10.92, respectively). In conclusion, the identified selenium-containing compounds hold potential structures as antileishmanial drug candidates to be further explored in subsequent studies. These findings represent a significant step toward the development of safer and more effective therapies for leishmaniasis, addressing the pressing need for novel and improved treatments.

Leishmanicidal Effects of Piperlongumine (Piplartine) and Its Putative Metabolites

Piperlongumine is an amide alkaloid found in Piperaceae species that shows a broad spectrum of biological properties, including antitumor and antiparasitic activities. Herein, the leishmanicidal effect of piperlongumine and its derivatives produced by a biomimetic model using metalloporphyrins was investigated. The results showed that IC50 values of piperlongumine in promastigote forms of Leishmania infantum and Leishmania amazonensis were 7.9 and 3.3 µM, respectively. The IC50 value of piperlongumine in the intracellular amastigote form of L. amazonensis was 0.4 µM, with a selectivity index of 25. The piperlongumine biomimetic derivatives, Ma and Mb, also showed leishmanicidal effects. We also carried out an in vitro metabolic degradation study showing that Ma is the most stable piperlongumine derivative in rat liver microsome incubations. The results presented here indicate that piperlongumine is a potential leishmanicidal candidate and support the biomimetic approach for development of new antileishmanial derivatives.

In Vitro TyRP-1 Knockdown Based on siRNA Carried by Liquid Crystalline Nanodispersions: an Alternative Approach for Topical Treatment of Vitiligo

PURPOSE

Vitiligo is a skin disease characterized by depigmentation and the presence of white patches that are associated with the loss of melanocytes. The most common explanation for the cause of this condition is that it is an autoimmune condition. TyRP-1 is involved in melanin pigment synthesis but can also function as a melanocyte differentiation antigen. This protein plays a role in the autoimmune destruction of melanocytes, which results in the depigmentation, characteristic of this disease. In this study, we evaluated liquid crystalline nanodispersions as non-viral vectors to deliver siRNA-TyRP-1 as an alternative for topical treatment of vitiligo.

METHODS

Liquid crystalline nanodispersions were obtained and characterized with respect to their physical-chemical parameters including size, PdI and zeta potential, as well as Small Angle X-ray Scattering and complexing to siRNA. The effects of the liquid crystalline nanodispersions on the cellular viability, cell uptake and levels of the knockdown target TyRP-1 were evaluated in melan-A cells after 24 h of treatment.

RESULTS

The liquid crystalline nanodispersions demonstrated adequate physical-chemical parameters including nanometer size and a PdI below 0.38. These systems promoted a high rate of cell uptake and an impressive TyRP-1 target knockdown (> 80%) associated with suitable loading of TyRp-1 siRNA.

CONCLUSIONS

We demonstrated that the liquid crystalline nanodispersions showed promising alternative for the topical treatment of vitiligo due to their physical parameters and ability in knockdown the target protein involved with autoimmune destruction of melanocytes.

Poly-epsilon-caprolactone nanoparticles enhance ursolic acid in vivo efficacy against Trypanosoma cruzi infection

Despite affecting millions of people worldwide, Chagas disease is still neglected by the academia and industry and the therapeutic option available, benznidazole, presents limited efficacy and side effects. Within this context, ursolic acid may serve as an option for treatment, however has low bioavailability, which can be enhanced through the encapsulation in polymeric nanoparticles. Therefore, herein we developed ursolic acid-loaded nanoparticles with poly-ε-caprolactone by the nanoprecipitation method and characterized them for particle size, zeta potential, polydispersity, encapsulation efficiency, morphology by scanning electron microscopy and thermal behavior by differential scanning calorimetry. Results indicated that an appropriate ratio of organic phase/aqueous phase and polymer/drug is necessary to produce smaller particles, with low polydispersity, negative zeta potential and high drug encapsulation efficiency. In vitro studies indicated the safety of the formulation against fibroblast culture and its efficacy in killing T. cruzi. Very importantly, the in vivo study revealed that the ursolic acid-loaded nanoparticle is as potent as the benznidazole group to control parasitemia, which could be attributed to improved bioavailability of the encapsulated drug. Finally, the toxicity evaluation showed that while benznidazole group caused liver toxicity, the nanoparticles were safe, indicating that this formulation is promising for future evaluation.

Galectin-1 exerts inhibitory effects during DENV-1 infection

Dengue virus (DENV) is an enveloped RNA virus that is mosquito-transmitted and can infect a variety of immune and non-immune cells. Response to infection ranges from asymptomatic disease to a severe disorder known as dengue hemorrhagic fever. Despite efforts to control the disease, there are no effective treatments or vaccines. In our search for new antiviral compounds to combat infection by dengue virus type 1 (DENV-1), we investigated the role of galectin-1, a widely-expressed mammalian lectin with functions in cell-pathogen interactions and immunoregulatory properties. We found that DENV-1 infection of cells in vitro exhibited caused decreased expression of Gal-1 in several different human cell lines, suggesting that loss of Gal-1 is associated with virus production. In test of this hypothesis we found that exogenous addition of human recombinant Gal-1 (hrGal-1) inhibits the virus production in the three different cell types. This inhibitory effect was dependent on hrGal-1 dimerization and required its carbohydrate recognition domain. Importantly, the inhibition was specific for hrGal-1, since no effect was observed using recombinant human galectin-3. Interestingly, we found that hrGal-1 directly binds to dengue virus and acts, at least in part, during the early stages of DENV-1 infection, by inhibiting viral adsorption and its internalization to target cells. To test the in vivo role of Gal-1 in DENV infection, Gal-1-deficient-mice were used to demonstrate that the expression of endogenous Galectin-1 contributes to resistance of macrophages to in vitro-infection with DENV-1 and it is also important to physiological susceptibility of mice to in vivo infection with DENV-1. These results provide novel insights into the functions of Gal-1 in resistance to DENV infection and suggest that Gal-1 should be explored as a potential antiviral compound.