Natural Abenquines And Their Synthetic Analogues Exert Algicidal Activity Against Bloom-Forming Cyanobacteria

Abenquines ate natural quinones, produced by some Streptomycetes, showing the ability to inhibit cyanobacterial growth in the 1 to 100 mu M range. To further elucidate their biological significance, the synthesis of several. analogues (4f-h, 5a-h) allowed us to identify some steric and electronic requirements for bioactivity. Replacing the acetyl by a benzoyl group in the quinone core and also changing the amino acid moiety with ethylpyrimidinyl or ethylpyrrolidinyl groups resulted in analogues 25-fold more potent than the natural abenquines. The two most effective analogues inhibited the proliferation of five cyanobacterial strains tested, with IC50 values ranging from 0.3 to 3 mu M. These compounds may be useful leads :for the development of an effective strategy for the control of cyanobacterial blooms.