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: Protozoários do gênero Phytomonas são parasitas prejudiciais a várias culturas agrícolas de importância econômica. Devido a sua atividade biológica reconhecida, extratos brutos de folhas de Piper aduncum, P. crassinervium, P. hispidum e P. amalago, foram testadas pela técnica de microdiluição em placa para avaliar o seu potencial antiparasitário contra Phytomonas serpens. Os resultados mostraram que o extrato bruto etanólico de P. crassinervium e P. amalago apresentaram as melhores concentrações inibitórias para 50% das células (IC50), 16,5 µg mL-1 na fase clorofórmio e 18 µg mL-1 na fase aquosa, respectivamente, após 48 h de tratamento. Análises de citotoxicidade foram realizadas através do método colorimétrico da sulforodamina-B, em células de mamíferos LLCMK2. A fase clorofórmio de P. crassinervium foi submetida ao processo de fracionamento, no qual as frações acetato de etila e diclorometano obtiveram melhores valores de IC50. Imagens de microscopia eletrônica de varredura (MEV) mostraram alterações na membrana celular dos parasitas tratados com fase aquosa de P. amalago. Os dados obtidos indicam potencial efeito antiparasitário das espécies de Piper analisadas contra P. serpens, sendo consideradas candidatas promissoras para formulações de bioprodutos para controle do parasito.

ABSTRACT: Protozoa of the genus Phytomonas are harmful parasites to several agricultural crops of economic importance. Due to their recognized biological activity, crude extracts of Piper aduncum, P. crassinervium, P. hispidum, and P. amalago leaves, were tested using the microdilution plate technique to assess the antiparasitic potential against Phytomonas serpens. Results showed that the ethanolic crude extract of P. crassinervium and P. amalago presented the best inhibitory concentration for 50% of the cells (IC50), 16.5 µg mL-1 in chloroform phase, and 18 µg mL-1 in aqueous phase, respectively, after 48 h treatment. Cytotoxicity analyses were performed using the colorimetric method of sulforhodamine-B in LLCMK2 mammalian cells. The chloroform phase of P. crassinervium was subjected to the fractionation process, in which the ethyl acetate and dichloromethane fractions obtained better IC50 values. Scanning electron microscopy (SEM) images showed alterations in the cell membrane of the treated parasites. The data obtained indicate a potential antiparasitic effect of the Piper species analyzed against P. serpens, being considered promising candidates for formulations of bioproducts to control the parasite.

The fungus Penicillium brasilianum LaBioMMi 136 was isolated as an endophyte from Melia azedarach and has shown to be a prominent producer of great diversity of secondary metabolites, although it does not express some biosynthetic routes to other natural compounds found in Penicillium genera. The present study aimed at the diversification of P. brasilianum secondary metabolism by varying the chemical composition used for its growth. Medium composition supplemented with CuSO4 and MnSO4 locked verruculogen biosynthesis and addressed proline to the production of a series of cyclodepsipeptides identified as JBIR 113, JBIR 114 and JBIR 115, never described for this species so far. The induced cyclodepsipeptide JBIR 113 was isolated by the use of combined chromatographic procedures and identified by spectroscopic methods. The unique structure with three neighboring cyclic amino acids proline and twice pipecolinic acid is rare as natural products and has been described for the first time in terrestrial organism. Verruculogen and JBIR 113 exhibited weak antiparasitary activity against Leishmania amazonensis.