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Studies on the effects of azadirachtin treatment, ecdysone supplementation and ecdysone therapy on both the ultrastructural organization of the rectum in 5th-instar nymph of Rhodnius prolixus and the ex vivo attachment behavior of Trypanosoma cruzi under these experimental conditions were carried out. Control insects had a typical and significant organization of the rectum cuticle consisted of four main layers (procuticle, inner epicuticle, outer epicuticle, and wax layer) during the entire period of the experiment. Both azadirachtin treatment and ecdysone supplementation avoid the development of both outer epicuticle and wax layer. Oral therapy with ecdysone partially reversed the altered organization and induce the development of the four main rectal cuticle layers. In the same way, the ex vivo attachment of T. cruzi to rectal cuticle was blocked by azadirachtin treatment but ecdysone therapy also partially recovered the parasite adhesion rates to almost those detected in control insects. These results point out that ecdysone may be a factor responsible - directly or indirectly - by the modulation of rectum ultrastructural arrangement providing a superficial wax layer to the attachment followed by metacyclogenesis of T. cruzi in the rectum of its invertebrate hosts., (Copyright © 2022 Elsevier Inc. All rights reserved.)

In this work, we analyze the leishmanicidal effects of epoxy-α-lapachone on Leishmania (Viannia) braziliensis and Leishmania (Leishmania) amazonensis. Promasigotes and amastigotes (inhabiting human macrophages) from both species were assayed to verify the compound's activity over the distinct morphological stages. The incubation with epoxy-α-lapachone led to a significant decrease in the numbers of promastigotes from both species in the cultures, in a dose-and time-dependent fashion. The survival of amastigotes inhabiting human macrophages was also drastically affected by the compound, as shown by the variations in the endocytic index. Our results indicate that the epoxy-α-lapachone has an antiparasitic effect over Leishmania in both morphological stages and may potentially affect a range of species in two distinct subgenera of this parasite., (Copyright © 2014 Elsevier Inc. All rights reserved.)

In this study we compared the effects of naphthoquinones (α-lapachone, β-lapachone, nor-β-lapachone and Epoxy-α-lap) on growth of Trypanosoma cruzi epimastigotes forms, and on viability of VERO cells. In addition we also experimentally analyzed the most active compounds inhibitory profile against T. cruzi serine- and cysteine-proteinases activity and theoretically evaluated them against cruzain, the major T. cruzi cysteine proteinase by using a molecular docking approach. Our results confirmed β-lapachone and Epoxy-α-lap with a high trypanocidal activity in contrast to α-lapachone and nor-β-lapachone whereas Epoxy-α-lap presented the safest toxicity profile against VERO cells. Interestingly the evaluation of the active compounds effects against T. cruzi cysteine- and serine-proteinases activities revealed different targets for these molecules. β-Lapachone is able to inhibit the cysteine-proteinase activity of T. cruzi proteic whole extract and of cruzain, similar to E-64, a classical cysteine-proteinase inhibitor. Differently, Epoxy-α-lap inhibited the T. cruzi serine-proteinase activity, similar to PMSF, a classical serine-proteinase inhibitor. In agreement to these biological profiles in the enzymatic assays, our theoretical analysis showed that E-64 and β-lapachone interact with the cruzain specific S2 pocket and active site whereas Epoxy-α-lap showed no important interactions. Overall, our results infer that β-lapachone and Epoxy-α-lap compounds may inhibit T. cruzi epimastigotes growth by affecting T. cruzi different proteinases. Thus the present data shows the potential of these compounds as prototype of protease inhibitors on drug design studies for developing new antichagasic compounds., (Copyright © 2010 Elsevier Inc. All rights reserved.)

Chagas disease is an endemic parasitic infection caused by Trypanosomacruzi that affects 18-20 million people in Central and South America. Recently we described the Epoxy-alpha-Lap, an oxyran derivative of alpha-lapachone, which presents a low toxicity profile and a high inhibitory activity against T.cruzi epimastigotes forms, the non-infective form of this parasite. In this work we described the trypanocidal effects of Epoxy-alpha-Lap on extracellular (trypomastigote) and intracellular (amastigote) infective forms of two T. cruzi strains (Y and Colombian) known by their different infective profile. Our results showed that Epoxy-alpha-Lap is lethal to trypomastigote Y and Colombian strains (97% and 84%, respectively). Interestingly, Epoxy-alpha-Lap also showed a trypanocidal effect in human macrophage infected with T. cruzi Y (85.6%) and Colombian (71.9%) strains amastigote forms. Similar effects were observed on T. cruzi amastigote infected Vero cells (96.4% and 95.0%, respectively). Our results pointed Epoxy-alpha-Lap as a potential candidate for Chagas disease chemotherapy since it presents trypanocidal activity on all T. cruzi forms with low) toxicity profile.

Leishmania proteinase activity is known as parasite differentiation marker, and has been considered relevant for leishmanial survival and virulence. These properties suggest that Leishmania proteinases can be promising targets for development of anti-leishmania drugs. Here, we analyze the activities of four proteinases during the early phase of the Leishmania amazonensis promastigotes differentiation into amastigotes induced by heat shock. We have examined activities of cysteine-, metallo-, serine-, and aspartic-proteinase by hydrolysis of specific chromogenic substrates at pH 5.0 and at the optimal pH for each enzyme. Our results show that metallo-, serine-, and aspartic-proteinases activities were down-regulated during the shock-induced transformation of promastigotes into amastigotes. In contrast, cysteine-proteinase activity increased concomitantly with the promastigote differentiation. Immunocytochemical localization using two anti-cysteine-proteinase monospecific rabbit antibodies detected the enzyme in several cell compartments of both parasite stages. Our results show different proteinase activity modulation and expression during the early phases of the shock-induced parasite transformation.