INHIBITORY ACTIONS OF GLYCYRRHIZIC ACID ON ARYLAMINE N-ACETYLTRANSFERASE ACTIVITY IN STRAINS OF HELICOBACTER-PYLORI FROM PEPTIC-ULCER PATIENTS

Arylamine N-acetyltransferase (NAT) activities with 2-aminofluorene (2 -AF) and p-aminobenzoic acid (PABA) as substrates were determined in H elicobacter pylori, collected from patients with peptic ulcers. The NA T activity was determined using an acetyl CoA recycling assay and high pressure liquid chromatography. Inhibition of growth studies from H. pylori demonstrated that glycyrrhizic acid elicited dose-dependent bac tericidal effect in H, pylori cultures, i.e.; the greater the concentr ation of glycyrrhizic acid, the greater the inhibition of growth of H. pylori. Cytosols or suspensions of H. pylori with and without selecte d concentrations of glycyrrhizic acid cotreatment showed different per centages of 2-AF and PABA acetylation. The data indicated that there w as decreased NAT activity associated with increased glycyrrhizic acid in H. pylori cytosols and intact cells. For the cytosol and intact bac teria examinations, the apparent values of Km and Vmax were decreased after co-treated with 80 M glycyrrhizic acid. This report is the first demonstration of glycyrrhizic acid inhibition of arylamine NAT activi ty and glycyrrhizic acid inhibition of growth in the bacterium H. pylo ri.