Leishmaniasis remains a significant global health concern, with current treatments relying on outdated drugs associated with high toxicity, lengthy administration, elevated costs, and drug resistance.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. The compounds were subjected to screening against L. amazonensis promastigotes, and their cytotoxicity was assessed in NIH/3T3 cells. Among the tested compounds, MRK-106 and MRK-108 displayed the highest potency against L. amazonensis promastigotes while demonstrating reduced cytotoxicity. Notably, MRK-106 and MRK-108 exhibited IC50 values of 3.97 µM, 4.23 µM, respectively, and most of the tested compounds showed low cytotoxicity in NIH/3T3 cells (CC50 > 200 µM). Although these results are promising, additional investigations focusing on intracellular amastigotes are required to determine the antileishmanial activity of the compounds. In conclusion, the identified selenium-containing compounds hold considerable potential as antileishmanial drug candidates and warrant further exploration in subsequent studies. These findings represent a significant step towards the development of safer and more effective therapies for leishmaniasis, addressing the pressing need for novel and improved treatments.

The Amazon region has the most incredible diversity of freshwater stingrays; however, there are still places where information about this group is scarce. The present work aims to record the occurrence of freshwater stingrays in the Uatumã river basin, Amazonas, Brazil. For this, collections were carried out in three municipalities bathed by the Uatumã River, Presidente Figueiredo, Itapiranga and São Sebastião do Uatumã. The rays were collected through fishing using a hand net and, after capture, were identified through the pattern of the dorsal and ventral color of the disc, the absence or presence of the labial groove and the organization of the row of spines on the tail, too were also measured, weighed and sexed. In total, 69 specimens of Potamotrygonines were captured, 59 of which were from the genus Potamotrygon and ten individuals from the genus Paratrygon. The present study provides preliminary information on the characteristics of freshwater stingray species that may occur in the Uatumã River. Furthermore, new research is necessary to improve the identification of specimens to determine the diversity and elucidate aspects related to the biology of elasmobranchs in the Uatumã River Basin, Brazil.

Leishmaniasis is a neglected tropical disease and affects more than 350 million people worldwide. However, there are no vaccines for humans, and current treatment is hampered due to its high cost, numerous side effects, and painful administration routes. Ending its epidemics by 2030 has become a United Nations goal, and the multitarget drug strategy emerges as a promising alternative. Flavonoids are an example of multitarget compounds and organic synthesis represents a tool to obtain high yields of these molecules. In our study, we synthesized 17 flavonoid analogs using a scalable, easy-to-reproduce, and inexpensive method. All compounds demonstrated an impressive inhibition capacity against rCPB2.8, rCPB3, and rH84Y, which are highly expressed in the amastigote stage, the target form of the parasite. Compounds 3c, f12a, and f12b stood out as effective against all isoforms and intermolecular interactions were investigated through a molecular modeling study. The compounds were highly potent against the parasite and demonstrated low cytotoxic action against mammalian cells. The results were pioneering, representing an advance in the investigation of the mechanisms behind the antileishmanial action of flavonoid derivatives. Furthermore, compounds have shown to be promising leads for the design of other cysteine protease inhibitors for the treatment of leishmaniasis diseases.