Abstract
BackgroundMajor drawbacks of the available treatment against Chagas disease (American trypanosomiasis) include its toxicity and therapeutic inefficiency in the chronic phase of the infection, which makes it a concern among neglected diseases. Therefore, the discovery of alternative drugs for treating chronic Chagas disease requires immediate action. In this work, we evaluated the mushroom Pleurotus salmoneostramineus in the search for potential antiparasitic compounds.MethodsFruit bodies of the basidiomycete Pleurotus salmoneostramineus were triturated and submitted to organic solvent extraction. After liquid-liquid partition of the crude extract, three fractions were obtained and the bioguided fractionation study was conducted to isolate the active metabolites. The elucidation of the chemical structure was performed using GC-MS and NMR techniques. The biological assays for antiparasitic activity were carried out using trypomastigotes of Trypanosoma cruzi and murine macrophages for mammalian cytotoxicity. The mechanism of action of the isolated compound used different fluorescent probes to evaluate the plasma membrane permeability, the potential of the mitochondrial membrane and the intracellular levels of reactive oxygen species (ROS).ResultsThe most abundant fraction showing the antiparasitic activity was isolated and chemically elucidated, confirming the presence of ergosterol. It showed anti-Trypanosoma cruzi activity against trypomastigotes, with an IC50 value of 51.3 μg/mL. The compound demonstrated no cytotoxicity against mammalian cells to the maximal tested concentration of 200 μg/mL. The mechanism of action of ergosterol in Trypanosoma cruzi trypomastigotes resulted in permeabilization of the plasma membrane, as well as depolarization of mitochondrial membrane potential, leading to parasite death. Nevertheless, no increase in ROS levels could be observed, suggesting damages to plasma membrane rather than an induction of oxidative stress in the parasite.ConclusionsThe selection of naturally antiparasitic secondary metabolites in basidiomycetes, such as ergosterol, may provide potential scaffolds for drug design studies against neglected diseases.
Highlights
Major drawbacks of the available treatment against Chagas disease (American trypanosomiasis) include its toxicity and therapeutic inefficiency in the chronic phase of the infection, which makes it a concern among neglected diseases
Phosphate-buffered saline (PBS), Roswell Park Memorial Institute Medium (RPMI 1640), Hank’s Balanced Salt Solution (HBSS), sodium azide, Triton X-100, carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone (FCCP), miltefosine, benznidazole (2-nitroimidazole), and the solvents dimethyl sulfoxide (DMSO), methanol (MeOH), hexane, ethyl acetate (EtOAc), butanol and dichloromethane were purchased from Sigma
Bioguided fractionation and antitrypanosomal activity The three obtained fractions (n-hexane, Ethyl acetate (EtOAc) and butanol) were incubated with free trypanosomes during 24 ho and the viability determined by the resazurin assay
Summary
Major drawbacks of the available treatment against Chagas disease (American trypanosomiasis) include its toxicity and therapeutic inefficiency in the chronic phase of the infection, which makes it a concern among neglected diseases. CD has been described more than 100 years ago, the chemotherapy is, so far, limited to two nitro-heterocyclic drugs: benznidazole and nifurtimox [6]. Both are effective in the acute phase of the infection, with approximately 60–80% efficacy [7]. They are considered far from ideal in the chronic phase of the disease, with severe adverse effects and reduced efficacy [7, 8]
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