Background: Brazilian propolis type 6 (Atlantic forest, Bahia) is distinct from the other types of propolis especially due to absence of flavonoids and presence of other non-polar, long chain compounds, but presenting good in vitro and in vivo antimicrobial activity. Several authors have suggested that fatty acids found in this propolis might be responsible for its antimicrobial activity; however, so far no evidence concerning this finding has been reported in the literature. The goals of this study were to evaluate the antibacterial activity of the main pure fatty acids in the ethanolic extract and fractions and elucidate the chemical nature of the bioactive compounds isolated from Brazilian propolis type 6.

BackgroundParasites of the Leishmania genus alternate between the flagellated extracellular promastigote stage and intracellular amastigotes. Here we report the characterization of a Leishmania isolate, obtained from a cutaneous leishmaniasis patient, which presents peculiar morphological features.MethodsThe parasite was cultured in vitro and characterized morphologically using optical and electron microscopy. Identification was performed based on monoclonal antibodies and internal ribosomal spacer typing. In vitro macrophage cultures, murine experimental models and sand fly infections were used to evaluate infectivity in vitro and in vivo.ResultsThe isolate was identified as Leishmania (Viannia) braziliensis. In the atypical promastigotes grown in culture, a short flagellum surrounded or interrupted by a protuberance of disorganized material was observed. A normal axoneme was present close to the basal body but without elongation much further outside the flagellar pocket. A disorganized swelling at the precocious end of the axoneme coincided with the lack of a paraflagellar rod structure. The isolate was able to infect macrophages in vitro, induce lesions in BALB/c mice and infect Lutzomyia longipalpis.ConclusionsNotwithstanding the lack of an extracellular flagellum, this isolate infects macrophages in vitro and produces lesions when inoculated into mice. Moreover, it is able to colonize phlebotomine sand flies. Considering the importance attributed to the flagellum in the successful infection and survival of Leishmania in the insect midgut and in the invasion of macrophages, these findings may bring new light into the infectious mechanisms of L. (V.) braziliensis.

Leishmania spp. release extracellular vesicles (EVs) containing parasite molecules, including several antigens and virulence factors. These EVs can interact with the host cells, such as immune cells, contributing to the parasite–host relationship. Studies have demonstrated that Leishmania-EVs can promote infection in experimental models and modulate the immune response. Although the immunomodulatory effect has been demonstrated, Leishmania-EVs can deliver parasite antigens and therefore have the potential for use as a new diagnostic tool and development of new therapeutic and vaccine approaches. This review aims to bring significant advances in the field of extracellular vesicles and Leishmania, focusing on their role in the cells of the immune system.

The present study aimed to characterize the chemical profile of essential oils of Rosmarinus officinalis (EORo) and Eucalyptus globulus (EOEg) cultivated in the mountainous region of the state of Rio de Janeiro, Brazil, and to verify the leishmanicidal potential, as well as to determine the cytotoxicity in vitro in mammalian cells. EORo had α-Pinene (37.99%), Cineol (21.48%), D-Verbenone (5.78%) and Limonene (3.28%) as major constituents. The EOEg had as major components Cineol (75.52%), Limonene (8.82%) and o-Cymeno (7.81%). The EOEg had a lower IC 50 value of 14.03 ± 2.08 µg/mL, while EORo had an IC 50 value of 31.12 ± 4.6 µg/mL, both during the 24-hr exposure period. In the 48-hr period, the IC 50 value was almost twice as high with rosemary oil, while in eucalyptus oil there was no significant difference when exposed in this period. The selectivity of EOs was demonstrated in murine cells, showing almost 30 times less toxic to the cell than to the parasite. It can be concluded that this is a pioneering study on the potential of these essential oils against the leishmania parasite. Furthermore, the low toxicity effect on the host cell encourages future studies and in vivo applications.