title: Inhibitory effect of flavonoids on N-acetylation of 5-aminosalicylic acid in cultured rat hepatocytes.
abstract: 5-Aminosalicylic acid (5-ASA) is an effective drug for the treatment of ulcerative colitis and Crohn's disease. A large group of flavonoids was investigated for their inhibitory effects on the N-acetyl-conjugation of 5-ASA in rat hepatocytes and subcellular preparations. When added to cultured hepatocytes, some flavonoids inhibited the production of N-acetyl-5-aminosalicylic acid (5-AcASA) with potencies that depended on the specific structure of flavonoids. Among the flavonols, quercetin, kaempferol and galangin had inhibitory activity with a tendency to be more effective at increasing the number of hydroxyl substitutions in the B-ring. Flavones such as luteolin, apigenin and chrysin were as effective as the corresponding three flavonols above. 7,3',4'-OH flavone was more effective than other simple flavones such as 7-, 5-, 3-, 7,3-, 7,4'- and 3',4'-OH flavones. Isoflavones were relatively weak inhibitors. Taxifolin and catechins had little or no inhibitory effect. These data suggest that the presence of C7 hydroxyl substitution on the A-ring and the catechol group on the B-ring in the flavone structure is required for effective inhibitory activity. The inhibitory effect of flavonoids on N-acetyl-conjugation of 5-ASA was also examined by incubating 5-ASA with isolated liver cytosolic preparations. The active flavonoids in the cells inhibited the N-acetylation of 5-ASA in the cell-free enzymatic preparations with a potency comparable to that for cultured rat hepatocytes.
authors.affiliation: Faculty of Pharmacy and Pharmaceutical Sciences, Fukuyama University, Sanzou, Gakuen-cho, Fukuyama, Hiroshima 729-0292, Japan.
authors.forename: Yuri
authors.initials: Y
authors.lastname: Mizoyama
authors.forename: Hisashi
authors.initials: H
authors.lastname: Takaki
authors.forename: Narumi
authors.initials: N
authors.lastname: Sugihara
authors.forename: Koji
authors.initials: K
authors.lastname: Furuno
mesh_terms: D000107:Acetylation / Q000187:drug effects; D000818:Animals; D002478:Cells, Cultured; D005419:Flavonoids / Q000494:pharmacology*; D022781:Hepatocytes / Q000378:metabolism*; D008297:Male; D019804:Mesalamine / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D005419:Flavonoids; D019804:Mesalamine