Bioactive secondary metabolites from new terrestrial Streptomyces sp. TN82 strain: Isolation, structure elucidation and biological activity

AbstractAn actinomycete strain designated TN82 was isolated from Tunisian Sahara soil and selected for its interesting antimicrobial activity against Gram positive and Gram negative bacteria and fungi. Based on the results of cultural characteristic, the 16S rRNA gene nucleotide sequence (1434 bp, accession n ° LT608133) and the phylogenetic analysis, this new isolate was assigned asStreptomyces sp. TN82 strain. Two active compounds, 3-phenylpyrazin-2(1H)-one (1) and 3-O-methylviridicatin (2), described for the first time as natural product and bacterial compound respectively, together with four known bacterial metabolites; cyclo-(Leu, Pro) (3), anthranilic acid (4), indole-3-carbaldehyde (5) andp-hydroxybenzoic acid (6) were isolated from the culture broth of this strain. Structure of the natural compound (1) was confirmed by extensive 1D and 2D NMR and EI MS and ESI HR mass measurements, and by comparison with literature data. Minimum inhibitory concentrations of the two compounds (1) and (2) against the tested human pathogenic bacteriaS. aureus,L. monocytogenes andS. typhimurium were significantly lower than those of kanamycin. For the natural compound 3-phenylpyrazin-2(1H)-one (1), MICs values were very interesting especially that againstL. monocytogenes (1.0  μg/mL) which is 2 and 12 times lower than those of ampicillin (2.0 μg/mL) and kanamycin (12.50 μg/mL), respectively.
Source: Medicinal Chemistry Research - Category: Chemistry Source Type: research