Carnivorous plants - Dionaea muscipula and Drosera capensis contain two major groups of pharmaceutically important substances, naphthoquinones: plumbagin, ramentaceone and flavonoids: myricetin, quercetin, which are considered to be responsible, i.e. for antibacterial properties of preparations from their tissues. This study focused on increasing bactericidal activity of the extracts of in vitro grown D. muscipula and D. capensis by stimulation of secondary metabolite synthesis by application of precursors of phenylpropanoid pathways (L-phenylalanine or trans-cinnamic acid) and elicitors: jasmonic acid, nitrogen deficiency, lysate of Agrobacterim rhizogenes. HPLC analysis of plant extracts indicated that bacterial lysate was the most successful elicitor of naphthoquinones (2.6-fold increase over control for plumbagin and 1.9 for ramentaceone). The addition Of L-phenylalanine and nitrogen depletion caused the highest accumulation of quercetin (1.6 - 2 times the control) and myricetin (1.6 - 1.8 times the control), respectively. The minimal bactericidal concentrations (MBCs) of selected extracts and purified compounds (naphthoquinones and flavonoids) were estimated against hospital isolates of human pathogenic bacteria. The lowest MBC values were observed for methanolic extract from D. muscipula grown on medium with L-phenylalanine (<= 25 -75 mg FW ml(-1)). These results show the potential of Droseraceae plants grown in vitro as a source of pharmaceutical material with valuable antimicrobial properties. (c) 2007 Elsevier Inc. All rights reserved.