The effects of plant phenolics, caffeic acid, chlorogenic acid and ferulicacid on arylamine N-acetyltransferase activities in human gastrointestinalmicroflora

The possible effects of naturally occurring plant phenolics, caffeic acid ( CA), chlorogenic acid (CGA) and ferulic acid (FA) on arylamine N-acetyltran sferase (NAT) activities on human gastrointestinal microflora, Escherichia coli, Klebsiella pneumoniae, Enterobacter aerogenes, Citrobacter koseri and Pseudomonas aeruginosa, were examined The bacterial NAT activities were de termined by HPLC measuring the acetylation of 2-aminofluorene (2-AF). Among all examined bacteria, P. aeruginosa exerted the highest NAT activity whil e C. koseri possessed the lowest NAT activity. CA, CGA and FA could suppres s the bacterial NAT activities dose-dependently both in the intact cell and cytosolic fraction analysis. According to the analysis of kinetic paramete rs in E. coli and P. aeruginosa, CA, CGA and FA were shown to be potent non competitive inhibitors of bacterial NAT activities. For the rime-course exp eriment, 4 mM of CA and FA could inhibit bacterial NAT activities for at le ast 4 hour brit 4 mM of CGA could, only significantly suppress NAT activity in E. coli for the same reaction time. These results strongly demonstrated that CA, CGA and FA inhibited NAT activities in human gastrointestinal bac teria.