Biotransformation of flobufen enantiomers in ruminant hepatocytes and subcellular fractions.
Flobufen (F), a new antiinflammatory drug, has one chiral and one prochiral center in its structure. Reduction of rac-F, the principal biotransformation pathway, leads to the formation of four diastereoisomers of 4-dihydroflobufen (DHF). F was chosen as a model substrate for interspecies comparison of activity, stereospecificity, and stereoselectivity of biotransformation enzymes in fallow bucks, red deer stags, and roe bucks in vitro. Formation of F metabolites was examined in hepatocyte suspension and in subcellular fractions of liver homogenate. (+)-R-F, (-)-S-F and rac-F were used as substrates. After incubation of substrates, the amounts and ratios of DHF diastereoisomers and F enantiomers were assessed by HPLC, with (R,R)-ULMO and terguride-bonded columns. Considerable interspecies differences in stereoselectivity and stereospecificity of F reductases were found at the cellular and subcellular levels, although these ruminants are closely related. Chiral inversion of F enantiomers to their antipodes was detected in vitro in all ruminants tested, but individual species also differed in the direction and rate of this inversion.
Skálová
L
L
Department of Biochemical Sciences, Faculty of Pharmacy, Research Centre LN 00B125, Charles University, Hradec Králové, Czech Republic. SKAOVAL@FAF.CUNI.CZ
Szotáková
B
B
Lamka
J
J
Král
R
R
Vanková
I
I
Baliharová
V
V
Wsól
V
V
D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000737:chemistry* / Q000493:pharmacokinetics*; D002087:Butyrates / Q000737:chemistry* / Q000493:pharmacokinetics*; D003600:Cytosol / Q000378:metabolism; D003670:Deer / Q000378:metabolism; D022781:Hepatocytes / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D008862:Microsomes, Liver / Q000378:metabolism; D010084:Oxidation-Reduction; D013045:Species Specificity; D013237:Stereoisomerism
D000894:Anti-Inflammatory Agents, Non-Steroidal; D002087:Butyrates; C056474:flobufen