RESUMO
Over the past years, natural products have been explored in order to find biological active substances to treat various diseases. Regarding their potential action against parasites such as trypanosomatids, specially Trypanosoma cruzi and Leishmania spp., much advance has been achieved. Extracts and purified molecules of several species from genera Piper, Tanacetum, Porophyllum, and Copaifera have been widely investigated by our research group and exhibited interesting antitrypanosomal and antileishmanial activities. These natural compounds affected different structures in parasites, and we believe that the mitochondrion is a strategic target to induce parasite death. Considering that these trypanosomatids have a unique mitochondrion, this cellular target has been extensively studied aiming to find more selective drugs, since the current treatment of these neglected tropical diseases has some challenges such as high toxicity and prolonged treatment time. Here, we summarise some results obtained with natural products from our research group and we further highlighted some strategies that must be considered to finally develop an effective chemotherapeutic agent against these parasites.
RESUMO
Abstract Chagas' disease is a parasitic infection caused by protozoan Trypanosoma cruzi that affect millions of people worldwide. The available drugs for treatment of this infection cause serious side effects and have variable efficacy, especially in the chronic phase of the disease. In this context, natural compounds have shown great potential for the discovery of new chemotherapies for the treatment of this infection and various other diseases. In present study, we evaluated the in vitro antiprotozoal activity of five species of Brazilian and Spanish marine sponges (Condrosia reniformes, Tethya rubra, Tethya ignis, Mycale angulosa and Dysidea avara) against T. cruzi. By GC–MS data, we observed that in these extracts were present the major classes of the following compounds: hydrocarbons, terpenes, steroids and alcohols. The extracts showed activity against the three forms of this parasite and did not induce toxicity in mammalian cells. Better activities were observed with the extracts of marine sponges, C. reniformes (EC50 = 0.6 μg/ml), D. avara (EC50 = 1.1 μg/ml) and M. angulosa (EC50 = 3.8 μg/ml), against trypomastigote forms. In intracellular amastigote forms, the extract of T. ignis showed IC50 of 7.2 μg/ml and SI of 24.65. On this basis, our results indicate that these extracts can be promising chemotherapeutic agents against T. cruzi.
RESUMO
Em trabalho anterior verificamos que neutrófilos oxidam o hormônio melatonina a N¹-acetil-N²-formil-5-metoxiquinuramina (AFMK), numa reação catalisada por mieloperoxidase e dependente de ânion superóxido. Neste trabalho acompanhamos a cinética de formação de AFMK e de seu produto de deformilação N¹-acetil-5-metoxiquinuramina (AMK) quando neutrófilos foram ativados por diferentes estímulos. No sentido de obtermos informações sobre a relevância biológica destas reações, avaliamos o efeito de melatonina, AFMK e AMK sobre a formação de HOCl, sobre a liberação de citocinas pró-inflamatórias (TNF-`alfa´ e IL-8) e sobre a apoptose de neutrófilos. Uma forte inibição da liberação de HOCl foi observada em concentrações de melatonina igual ou superior a 0,05 mM...