Inhibitory actions of emodin on arylamine N-acetyltransferase activity in strains of Helicobacter pylori from peptic ulcer patients

• Published in: Food and chemical toxicology 1997-10, Vol.35 (10), p.1001-1007
• Main Authors: Chung, J.G., Wang, H.H., Wu, L.T., Chang, S.S., Chang, W.C.
• Format: Article
• Language: English
• Subjects: 2-aminofluorene; 4-Aminobenzoic Acid - metabolism; Acetylation - drug effects; Arylamine N-Acetyltransferase - antagonists & inhibitors; Arylamine N-Acetyltransferase - drug effects; Biological and medical sciences; Cytosol - drug effects; Cytosol - microbiology; Digestive system; emodin; Emodin - pharmacology; Enzyme Inhibitors - pharmacology; Fluorenes - metabolism; Helicobacter Infections - metabolism; Helicobacter pylori; Helicobacter pylori - enzymology; Helicobacter pylori - isolation & purification; Humans; Kinetics; Medical sciences; N-acetyl- p-aminobenzoic acid; N-acetyl-2-aminofluorene; N-acetyltransferase; p-aminobenzoic acid; Peptic Ulcer - microbiology; Pharmacology. Drug treatments
• ISSN: 0278-6915; 1873-6351
• DOI: 10.1016/S0278-6915(97)87269-9

Arylamine N-acetyltransferase (NAT) activities with p-aminobenzoic acid and 2-aminofluorene were determined in Helicobacter pylori, a gram-negative rod bacteria collected from peptic ulcer patients. The NAT activity was determined using a acetyl CoA recycling assay and HPLC. Cytosols or suspensions of H. pylori with and without selected concentrations of emodin co-treatment showed different peventages of 2-aminofluorene and p-aminobenzoic acid acetylation. The data indicate that there were decreased NAT activity associated with increased emodin in H. pylori cytosols. As 400 μM of emodin can obviously inhibit NAT activity both in vitro and in vivo (inhibition rate 90% and 93% for 2-aminofluorene and p-aminobenzoic acid in vitro, and 90% and 92%, respectively, for both substrate in vivo). For in vitro examination, the apparent values of K m and V max were 3.12 ± 0.38 m m and 15.20 ± 3.16 nmol/min/mg protein for 2-aminofluorene, and 0.56 ± 0.12 m and 0.74 ± 0.09 nmol/min/mg protein for p-aminobenzoic acid. However, when emodin was added to the reaction mixtures, the values of apparent K m and V max were 2.40 ± 0.32 m m and 10.62 ± 0.04 nmol/min/mg protein for 2-aminofluorene, and 0.23 ± 0.02 m m and 0.62 ± 0.08 nmol/min/mg protein for p-aminobenzoic acid. For in vivo examination, the apparent K m and V max were 0.82 ± 0.18 m m and 0.92 ± 0.21 nmol/min/10 × 10 10 colony forming units (CFU) for 2-aminofluorene, and 0.78 ± 0.14 m m and 0.52 ± 0.06 nmol/min/ 10 × 10 10 (CFU) for p-aminobenzoic acid. However, when emodin was added to the reaction mixtures, the values of apparent K m and V max were 0.50 ± 0.08 m m and 0.62 ± 0.22 nmol/min/ 10 × 10 10 (CFU) for 2-aminofluorene, and 0.52 ± 0.21 m m and 0.26 ± 0.04 nmol/min/ 10 × 10 10 (CFU) for p-aminobenzoic acid. This report is the first finding of emodin inhibition of arylamine N-acetyltransferase activity in a strain of H. pylori.