Antileishmanial activity of the essential oils of Myrcia ovata Cambess. and Eremanthus erythropappus (DC) McLeisch leads to parasite mitochondrial damage.

Leishmania amazonensis is a species causative of cutaneous and anergic diffuse cutaneous leishmaniasis, treatment-resistant form, in the New World. Plants essential oils exhibit great potential as microbicide agents. We described the composition of the essential oils of two plants native from Brazil, Myrcia ovata, with geranial and neral as major constituents, and Eremanthus erythropappus, with α-bisabolol. In vitro effects of these essential oils on L. amazonensis promastigotes growth and ultrastructure were analysed as well as their cytotoxicity to murine macrophages. Both oils were highly active with IC50/96 h of 8.69 and 9.53 µg/mL for M. ovata and E. erythropappus against promastigotes and caused ultrastructural alterations including mitochondrial enlargement. Cytotoxicity for murine macrophages varied with the oil concentrations. The IC50 low values of both M. ovata and E. erythropappus oils against L. amazonensis and their relative low cytotoxicity to mammal host cells support their potential use against cutaneous leishmaniasis.

Establishment and quantitative measure of Stomoxys calcitrans (Linnaeus, 1758) colony production in Rio de Janeiro, Brazil.

Functional insect vector colonies are essential for the study of their biology, evolution, behavior as well as control strategies of these organisms that transmit pathogens of medical and veterinary importance. In addition to the establishment, improvement and adaptation of pre-established protocols in the maintenance of a colony is important, as it may result in higher production of insects. Stomoxys calcitrans or stable fly causes important economic losses in production of beef and milk, besides mechanically transmitting a great variety of pathogens to cattle. In order to generate flies under laboratory conditions, a colony of S. calcitrans was established at our laboratory considering local environment geographical characteristics. Adults collected in UFRRJ campus were kept in the laboratory and maintained with daily feeding on anticoagulant-containing bovine blood offered in disposable sanitary napkins. Immature forms were maintained on diets rich in organic matter. The colony temperature and relative humidity were daily monitored as well as the development of insects. The monthly measured biological parameters included the development of eggs into pupae, of pupae into F1 adults and the comparison of the number of flies collected in the field with the number of F1 flies emerged in the laboratory. The data presented here was obtained from March to November 2019. In that period, the average per month of flies collected in the field was 604.2, of generated eggs was 2694.3, of generated pupae was 349.5 and of generated F1 flies in the laboratory was 205.9. Fluctuations of abiotic and biological factors contributed to an uneven production of flies in the colony throughout the months. This is the first report with numerical quantification of S. calcitrans flies production in a laboratory in Brazil. Some methodologies used in the colony shall be reevaluated and modified with the goal of obtaining higher numbers of flies generated in the laboratory over time.

The effect of the biflavonoid 2″,3″-dihydroochnaflavone on Trypanosoma cruzi Y strain.

Trypanosoma cruzi is the causative agent of Chagas disease which affects 8 million people in Latin America. The parasite possesses high capacity to evade host immune system and the available drugs to treat Chagas disease present low efficacy combined to serious side effects to patients. Therefore, the identification of alternative therapeutics is essential. Brazilian flora exhibits an immense diversity of metabolites with great potential to be developed into new drugs. We investigated the action of 2″,3″-dihydroochnaflavone a biflavonoid extracted from Luxemburgia nobilis Eichler ex Engl. (Ochnaceae) against T. cruzi (Y strain). Our experiments showed that this compound is effective against parasite epimastigote forms, presenting IC50 value of (2.5 ± 0.1) µM after 96 h of treatment. Ultrastructure alterations were also detected in treated epimastigotes especially mitochondrial enlargement at the kinetoplast region. At the concentration of 30 µM, the compound killed (61.6 ± 3.37)% of the parasite in its amastigote form. In addition, at the same concentration, the compound killed all trypamastigotes growing within murine macrophages after 7-9 days of infection. Nonetheless, the biflavonoid concentrations were harmless to murine enriched population of lymphocytes and peritoneal macrophages. These results indicate that 2″,3″- dihydroochnaflavone presents activity against T. cruzi.