Planta Med 2007; 73 - P_097
DOI: 10.1055/s-2007-986879

Bromoanaindolone – a new antimicrobial active metabolite excreted by the cyanobacterium Anabaena constricta

RB Volk 1, U Girreser 2, M Al-Refai 3, H Laatsch 3, W Blaschek 1
  • 1Pharmaceutical Institute, Department of Pharmaceutical Biology, University of Kiel, Gutenbergstraße 76, D-24118 Kiel, Germany
  • 2Pharmaceutical Institute, Department of Pharmaceutical Chemistry, University of Kiel, Gutenbergstraße 76, D-24118 Kiel, Germany
  • 3Institute for Organic and Biomolecular Chemistry, University of Göttingen, Tammannstraße 2, D-37077 Göttingen, Germany

Cyanobacteria have been increasingly recognized as an excellent source of biologically active metabolites, fine chemicals (e.g. vitamins, polyunsaturated fatty acids, proteins) and other useful natural products [1]. Within our own research activities in this field of interest, a new brominated indole alkaloid, designated as bromoanaindolone, was isolated from culture media of the cyanobacterium Anabaena constricta. By means of IR, MS and NMR data, the molecular structure of this cyanobacterial exometabolite was identified as 6-bromo-3-hydroxy-3-methyl-indol-2-one (1) with a slight excess of the (3R) enantiomer. For the isolated and purified compound an antimicrobial activity in different test systems such as suspension and porous matrix tests was quantifiable (minimum toxic quantities against cyanobacteria: 8–20µg; minimum inhibitory concentration against bacteria: 128µg ml-1). Thus, these results point to a natural function of bromoana-indolone as an allelopathic substance as outlined for other antimicrobial exometabolites of cyanobacteria earlier [2,3,4].

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References: [1] Singh, S. et al. (2005) Crit Rev Biotechnol 25: 73–95. [2] Volk, R.-B. (2005) J Appl Phycol 17: 339–347. [3] Volk, R.-B., Furkert, F.H. (2006) Microbiol Res 161: 180–186. [4] Blom, J.F. et. al. (2005) Org Lett 8: 737–740.