Antibacterial activity of endophytic fungi associated with Aspidosperma subincanum Mart. against Gram-positive bacteria

Abstract

Endophytic fungi are microorganisms that inhabit plant tissues, without causing damage to the host. When in association with medicinal plants, they are able to prompt the production of secondary metabolites with important biological activities. The aim of this study was to evaluate the antibacterial activity of endophytic fungi associated with Aspidosperma subincanum against Gram positive bacteria of clinical relevance and perform the chemical characterization of the extract with the highest antibacterial activity. Endophytic fungi isolated from leaves of A. subincanum were submitted to ethanolic extraction. The antibacterial activity of the extracts was evaluated against S. aureus ATCC 25923, using the microdilution method. From a total of 116 extracts, only 4 (3.44%) were considered positive and then evaluated against B. cereus. The ethanolic endophytic extract AM59.1-98 was able to completely inhibit the growth of both microorganisms and was selected for chemical characterization, which indicated the presence of saponins and tannins. Further studies have to be conducted to confirm if the chemical substances detected are those responsible for its antibacterial activity. The current research provides, for the first time, substantial results concerning the antibacterial activity of endophytes associated with A. subincanum as an alternative path in the search for new drugs.