Endophytic Actinobacteria from the Brazilian Medicinal Plant Lychnophora ericoides Mart. and the Biological Potential of Their Secondary Metabolites

Abstract

Endophytic actinobacteria from the Brazilian medicinal plant Lychnophora ericoides were isolated for the first time, and the biological potential of their secondary metabolites was evaluated. A phylogenic analysis of isolated actinobacteria was accomplished with 16S rRNA gene sequencing, and the predominance of the genus Streptomyces was observed. All strains were cultured on solid rice medium, and ethanol extracts were evaluated with antimicrobial and cytotoxic assays against cancer cell lines. As a result, 92% of the extracts showed a high or moderate activity against at least one pathogenic microbial strain or cancer cell line. Based on the biological and chemical analyses of crude extracts, three endophytic strains were selected for further investigation of their chemical profiles. Sixteen compounds were isolated, and 3-hydroxy-4-methoxybenzamide (9) and 2,3-dihydro-2,2-dimethyl-4(1H)-quinazolinone (15) are reported as natural products for the first time in this study. The biological activity of the pure compounds was also assessed. Compound 15 displayed potent cytotoxic activity against all four tested cancer cell lines. Nocardamine (2) was only moderately active against two cancer cell lines but showed strong activity against Trypanosoma cruzi. Our results show that endophytic actinobacteria from L. ericoides are a promising source of bioactive compounds.

Molecular inter-kingdom interactions of endophytes isolated from Lychnophora ericoides

“…Particularly, chemical families from S . mobaraensis RLe3, which showed a high cytotoxicity activity against cancer cells in our previous study 44 , and S . albospinus RLe7, an amphotericin B ( 1 ) producer 45 , were identified by performing complementary approaches involving mono- and co-cultures, characterization of isolated compounds via NMR and MS, as well as molecular networking workflow.…”

“…albospinus RLe7 corresponds to the pyrroloindole alkaloid physostigmine (compound 2 ) 44 . As it is a characterized natural product from this endophytic actinobacterium, the detection of physostigmine during microbial interaction was expected.…”

“…Although S . albospinus RLe7 showed a low cytotoxicity against cancer cell lines 44 , it induced a particular fungal response in the endophytic Coniochaeta sp. FLe4 due to the production of amphotericin B ( 1 ) 45 .…”

“…Due to the importance of this plant in folk medicine 42, 43 , and the interesting biosynthetic potential of endophytic microorganisms 13 , we initiated the investigation of natural products from endophytes of L . ericoides 44 . A total of sixteen compounds were isolated from endophytic actinobacteria of L .…”

“…A total of sixteen compounds were isolated from endophytic actinobacteria of L . ericoides , revealing these microorganisms as a promising source of natural products 44 . This potential was also demonstrated in a recent study where we investigated the chemical arsenal produced by one of these endophytic actinobacteria strains, Streptomyces albospinus RLe7 45 .…”