Antibacterial properties of Polygonum cuspidatum roots and their major bioactive constituents

Antibacterial activity, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) of crude extract from Polygonum cuspidatum roots were assayed against five common foodborne bacteria (Bacillus cereus, Listeria monocytogenes, Staphylococcus aureus, Escherichia coli, and Salmonella anatum). The crude extract exhibited potent antibacterial properties. Major bioactive compounds in P. cuspidatum roots were identified as stilbenes (e.g., piceid, resveratroloside, and resveratrol) and hydroxyanthraquinones (e.g., emodin, emodin-1-O-glucoside, and physcion) by LC-ESI-MS. Both stilbenes and hydroxyanthraquinoines greatly contributed to the antibacterial properties. Additionally, scanning electron microscopy was used to observe morphological changes of the bacteria treated with the crude extract and its major antibacterial components. Possible mechanisms of the antibacterial action were also discussed. This study suggests that the roots of P. cuspidatum and its antibacterial components may have potential for use as natural preservatives. (C) 2008 Elsevier Ltd. All rights reserved.