Effects of caffeic acid, chlorogenic acid and ferulic acid on growth and arylamine N-acetyltransferase activity in Shigella sonnei (group D)

Arylamine N-acetyltransferase (NAT) activities with a-aminofluorene (2-AF) as substrates were determined in Shigella sonnei (group D) collected from p atients with diarrhoeal disease. The NAT activity was determined using an a cetyl CoA recycling assay and high pressure liquid chromatography. Inhibiti on of growth studies from S. sonnei (group D) demonstrated that caffeic aci d (CA), chlorogenic acid (CGA) and ferulic acid (FA) elicited a dose-depend ent bactericidal effect in S. sonnei (group D) cultures, i.e. the greater t he concentration of CA, CGA and FA, the greater the inhibition of growth of S. sonnei(group D). Cytosols or suspensions of S. sonnei(group D) with and without selected concentrations of CA, CGA and FA co-treatment showed diff erent percentages of 2-AF acetylation. The data indicated that there was re duced NAT activity associated with increased CA, CGA and FA in Shigella dys enteriae (group D) cytosols and intact cells. For the cytosol and intact ba cteria examinations, the apparent values of K-m and V-max decreased after b eing co-treated with 400 mu M CA, CGA and FA. This report is the first demo nstration of plant phenolic inhibition (CA, CGA and FA) of arylamine NAT ac tivity and growth in the bacterium S. sonnei (group D).