Bromoanaindolone, a novel antimicrobial exometabolite from the cyanobacterium Anabaena constricta.

A new brominated indole alkaloid, designated as bromoanaindolone, was isolated from culture media of the cyanobacterium Anabaena constricta and was identified as 6-bromo-3-hydroxy-3-methyl-indol-2-one with a slight excess of the (3R) enantiomer. The molecular structure was elucidated on the basis of IR, MS and NMR data. This extracellular metabolite of A. constricta possessed antimicrobial (anticyanobacterial and antibacterial) activity in different test systems, such as suspension and porous matrix tests.