Fungos endófitos do cacau: seleção e avaliação da atividade antimicrobiana, antioxidante e antiproliferativa do extrato da fermentação de Microsphaeropsis sp.

Abstract

Nowadays, there is an increasing interest in endophytics fungi research as a source oh bioactive substances that could be applied in agriculture for pest control, and even for the discovery of new drugs. Like any plant, Theobroma cacao L. serves as habitat for diverse fungal endophytes that live within plant tissues in a symbiotic, mutualistic or parasitic. A total of 37 strains of fungal endophytes isolated in Theobroma cacao L. were cultured in vitro and their extracts were analyzed, and a fungus was selected for investigation of the antimicrobial, antioxidant and antiproliferative activities. The fungus endophyte Microsphaeropsis sp. CML 1765 presented a satisfactory growth and stability in addition to good antimicrobial activity against S. aureus. The results of minimum inhibitory concentration (MIC) of the extract from fermented Microsphaeropsis sp were between 62.5 and 125 µg/mL. The chemical composition analysis of the extracts was carried by CG/MS and allowed the identification of fatty acids and steroids as main components. The antioxidant activity was determined using the DPPH test and was not significant, possibly because it contains phenolic compounds in their chemical composition. The antiproliferative activity was tested against nine cancer cell lines and extract Microsphaeropsis sp. showed selectivity against melanoma cells (UACC-62) reaching the TGI (total growth inhibition) at a concentration of 4 µg/mL. The extracts was cytostatic and cytocide for all cell lines at concentration of 25 µg/mL and 250 µg/mL, respectively. The diversity of nature opens the way for studies on fungal endophytes that are natural sources of unexplored bioactive metabolites with therapeutic potential unknown.