PUB - Publikationen an der Universität Bielefeld

An 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 nA degrees LT608133) and the phylogenetic analysis, this new isolate was assigned as Streptomyces 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) and p-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 bacteria S. aureus, L. monocytogenes and S. 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 against L. monocytogenes (1.0 mu g/mL) which is 2 and 12 times lower than those of ampicillin (2.0 mu g/mL) and kanamycin (12.50 mu g/mL), respectively.