Microbispora sp. LGMB259 endophytic actinomycete isolated from Vochysia divergens (Pantanal, Brazil) producing β-carbolines and indoles with biological activity.

Endophytic actinomycetes encompass bacterial groups that are well known for the production of a diverse range of secondary metabolites. Vochysia divergens is a medicinal plant, common in the "Pantanal" region (Brazil) and was focus of many investigations, but never regarding its community of endophytic symbionts. During a screening program, an endophytic strain isolated from the V. divergens, was investigated for its potential to show biological activity. The strain was characterized as Microbispora sp. LGMB259 by spore morphology and molecular analyze using nucleotide sequence of the 16S rRNA gene. Strain LGMB259 was cultivated in R5A medium producing metabolites with significant antibacterial activity. The strain produced 4 chemically related β-carbolines, and 3 Indoles. Compound 1-vinyl-β-carboline-3-carboxylic acid displayed potent activity against the Gram-positive bacterial strains Micrococcus luteus NRRL B-2618 and Kocuria rosea B-1106, and was highly active against two human cancer cell lines, namely the prostate cancer cell line PC3 and the non-small-cell lung carcinoma cell line A549, with IC50 values of 9.45 and 24.67 µM, respectively. 1-Vinyl-β-carboline-3-carboxylic acid also showed moderate activity against the yeast Saccharomyces cerevisiae ATCC204508, as well as the phytopathogenic fungi Phyllosticta citricarpa LGMB06 and Colletotrichum gloeosporioides FDC83.