Barakacin: a thiazolyl-indole alkaloid isolated from a ruminal Pseudomonas sp.
A new thiazolyl-indole alkaloid, barakacin (1), has been isolated from the ruminal bacterium Pseudomonas aeruginosa strain ZIO. On the basis of detailed spectroscopic analyses and comparison with the data of related compounds, its structure has been determined as 2-{4-[bis-(1H-indol-3-yl)-methyl]-thiazol-2-yl}-phenol. In addition, the known compounds phenazine-1-carboxylic acid, 3-(hydroxyacetyl)-indole, indole-3-carbaldehyde, and glycolipid A were isolated. The discovery of compounds with a new skeleton emphasizes the importance for exploring new ecological niches like the rumen of bovines for the detection of new natural products. This paper describes the fermentation, isolation, structure elucidation and biological activities of compound 1.