Abstract
Neglected tropical diseases as Chagas disease (CD) affect more than eight million people, mainly in the Americas, causing fatal cardiovascular outcomes. Relying on two old, toxic, and low efficacy drugs for treatment, there is an urgent need for new candidates. Comprising a high chemodiversity, marine bacteria are a rich source of small molecules with potential against human pathogens. Cultivation-based strategies of bacteria, such as the one strain many compounds (OSMAC) approach, have proven to be a simple and promising tool for drug discovery, with the ability to stimulate the expression of cryptic genes in microorganisms. In this study, using the OSMAC, we evaluated the potential of the marine bacteria Metabacillus indicus to produce anti-Trypanosoma cruzi compounds with higher potency. The M. indicus was cultivated under different conditions, subdivided into four groups, as nutritional, physical, biological, and chemical alterations. For comparisons, the extract obtained from the bacteria in Marine Broth (static) at 25 °C was used as a control and resulted in an EC(50) value of 28 μg/mL against the trypomastigotes. The physical alterations proved to be the most effective approach to improve the potency of M. indicus metabolites, resulting in EC(50) values between 3 and 26 μg/mL. The cultivation in Marine Agar potentiated the antitrypanosomal metabolites by 8.4-fold. When exposed to cobalt-60 γ radiation (0.5 kGy), the bacteria produced metabolites with 2-fold higher antitrypanosomal potency. The nutritional alterations resulted in potent metabolites, with EC(50) values between 11 and 18 μg/mL, while biological alterations resulted in EC(50) values between 11 and 28 μg/mL. Addition of T. cruzi and Leishmania infantum antigens and co-cultivation with Acinetobacter baumannii, enhanced by 2-fold the potency. Chemical elicitors such as DMSO and EtOH demonstrated no improvements for M. indicus cultivation. The chemical profile of M. indicus was analyzed using NMR and UHPLC-ESI-HR-MS/MS and processed using the GNPS platform, which led to the annotation of nucleosides, dipeptides, steroids, and fatty acid derivatives. These findings confirmed that the OSMAC approach yielded not only distinct antitrypanosomal activities but also distinct metabolomic profiles in M. indicus that could be exploited for drug discovery studies for Chagas disease.