Inhibitory Effect of Plant Extracts on Production of Verotoxin by Enterohemorrhagic Escherichia coli O157 : H7

The inhibitory effect of several plant extracts on the production of verotoxin by enterohemorrhagic Escherichia coli O157 : H7 (EHEC) was investigated. The extracts from four plant species, Limonium californicum (Boiss.) A. Heller, Cupressus lustianica Miller, Salvia urica Epling and Jusiaea peruviana L., were effective on the inhibition for verotoxin production (31.3-125 μg/ml). The inhibition against verotoxin production was observed at a concentration lower than the minimal inhibitory concentration (MIC) of each extract of test plants (1000 μg/ml), indicating that these plant extracts would preferentially prevent the production of verotoxin rather than bactericidal effect on EHEC. These findings suggest that the administration of any appropriate plant extract might prevent the production of verotoxin on EHEC in the human intestines.