Antialgal, antibacterial and antifungal activity of two metabolites produced and excreted by cyanobacteria during growth

The antimicrobial activity of two cyanobacterial exometabolites, norharmane (9H-pyrido(3,4-b)indole) and 4,4'-dihydroxybiphenyl, was determined in suspension assays. Good anticyanobacterial activities (concentrations of 8-80 mu g ml(1)) and moderate antibacterial (16-160 mu g ml (1)) and antifungal (32 40 mu g ml(1)) activities were found for both compounds. The natural function as alletopathic chemicals and a possible applicability as antifouling agents or leads for the development of new antifouling chemicals are discussed. (C) 2005 Elsevier GmbH. All rights reserved.