Estimation of flavin-containing monooxygenase activity in intact hepatocyte monolayers of rat, hamster, rabbit, dog and human by using N-oxidation of benzydamine.
The flavin-containing monooxygenase (FMO)-dependent N-oxidation of benzydamine has been assessed as a method for monitoring the activity of FMOs in monolayer cultures of hepatocytes from rat, dog, rabbit, hamster and human. The advantage of this substrate is that benzydamine N-oxide formation can be measured directly in extracts of cellular incubations without an intensive work-up procedure. Benzydamine and its N-oxide are readily separated by HPLC with fluorometric detection. This assay proved sensitive enough to monitor FMOs activity in intact monolayer of cultured hepatocytes. The formation of benzydamine N-oxide was inhibited when hepatocytes were coincubated with methimazole (another FMO substrate) in a dose-dependent manner, whereas N-octylamine (an inhibitor of cytochrome P450) had no inhibitory effect. In contrast to cytochrome P450, FMO activity assessed by benzydamine N-oxidation was relatively stable for all species studied during 72-h cultures.
Ubeaud
G
G
F. Hoffmann-La Roche Ltd., Pharma Division, Preclinical Research, Basel, Switzerland. ubeaud@pharma.u-strasbg.fr
Schiller
C D
CD
Hurbin
F
F
Jaeck
D
D
Coassolo
P
P
D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000378:metabolism*; D001591:Benzydamine / Q000378:metabolism*; D002478:Cells, Cultured; D006224:Cricetinae; D004285:Dogs; D004789:Enzyme Activation; D006801:Humans; D008099:Liver / Q000166:cytology / Q000201:enzymology*; D008297:Male; D008647:Mesocricetus; D010084:Oxidation-Reduction; D010105:Oxygenases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011817:Rabbits; D051381:Rats
D000894:Anti-Inflammatory Agents, Non-Steroidal; D001591:Benzydamine; D010105:Oxygenases; C020066:dimethylaniline monooxygenase (N-oxide forming)