Constituents from stem barks of Luehea ochrophylla Mart and evaluation of their antiparasitic, antimicrobial, and antioxidant activities.

Luehea species are found in almost all Central and South American countries. The present work describes the phytochemical study, isolation, and structural characterisation of friedelin, ß-friedelinol, lupeol, pseudotaraxasterol, ß-sitosterol, betulinic acid, taraxasterol, (-)-epicatechin, ß-sitosterol-3-O-ß-d-glucopyranoside, and (+)-epicatechin-(4ß→8)-epicatechin from stem barks of Luehea ochrophylla Mart. The structural identification of the isolated compounds was mainly performed by NMR analyses and comparison with the data from literature. These compounds were isolated for the first time in the genus Luehea, except ß-sitosterol glucopyranoside, (-)-epicatechin, and lupeol. Hexane extract (HE) and dichloromethane (DF) and ethyl acetate (AF) fractions exhibited antiparasitic activity against amastigote (intracellular) and trypomastigote culture forms of Trypanosoma cruzi. The ethanol extract (EE), DF, and ethanol fraction (EF) exhibited considerable antifungal activity against Candida albicans. Moreover, extracts and fractions exhibited significant percentage of capture free radicals of 2,2-diphenyl-picrylhydrazyl (DPPH) when compared to the standard of ascorbic acid.

Functional analysis of iron superoxide dismutase-A in wild-type and antimony-resistant Leishmania braziliensis and Leishmania infantum lines.

In this work, we characterized the gene encoding iron superoxide dismutase-A (FeSOD-A) in wild-type (WTS) and antimony-resistant (SbR) L. (Viannia) braziliensis and L. (Leishmania) infantum lines, which were selected in vitro. FeSOD-A transcript and protein expression were similar in all tested lines; however, specific enzyme activity analysis revealed higher superoxide dismutase activity in SbIII-resistant LbSbR and LiSbR lines than in the corresponding WTS lines. These parasites were also more tolerant to oxidative stress generated by the herbicide paraquat. Functional analysis showed that in comparison to non-transfected lines, wild-type LbWTS and LiWTS clones overexpressing the FeSOD-A enzyme are 1.6- and 1.7-fold more resistant to SbIII, respectively. Our results suggest that FeSOD-A is involved in the antimony resistance phenotype in L. (V.) braziliensis and L. (L.) infantum.

Influence of the long-term Trypanosoma cruzi infection in vertebrate host on the genetic and biological diversity of the parasite.

The influence of the long-term Trypanosoma cruzi infection in vertebrate host on the biological and genetic properties of the parasite was evaluated. Four T. cruzi isolates obtained from different chronic chagasic dogs infected with Berenice-78 T. cruzi strain during 2 and 7 years were comparatively analyzed. The long-term T. cruzi infection has led to alterations in parasitemia, virulence and pathogenicity of Be-78 strain for mice. These biological parameters varied from low to high in realation to the parental strain. Randomly amplified polymorphic DNA and isoenzyme profiles detected two distinct genetic groups of parasites. The first group included the parental strain and two T. cruzi isolates, and the second group the two other isolates. Interestingly, the isolates of the second group showed a reversibility of the genetic profile to the parental strain after 25 passages in mice. No correlation between the genetic groups and biological properties of the isolates was observed. Our findings confirmed the population heterogeneity of the Be-78 strain, and showed how differently it responds to the long-term infection in the same vertebrate hosts.