title: Inhibitory effects of diesel exhaust components and flavonoids on 20alpha-hydroxysteroid dehydrogenase activity in mouse tissues.
abstract: The inhibitory effects of diesel exhaust components and flavonoids on 20alpha-hydroxysteroid dehydrogenase (20alpha-HSD) activity were examined in cytosolic fractions from the liver, kidney and lung of male mice. 9,10-Phenanthrenequinone (9,10-PQ) and 1,2-naphthoquinone (1,2-NQ), which are contained in diesel exhaust particles (DEPs), potently inhibited 20alpha-HSD activity in liver cytosol. 9,10-PQ also inhibited the enzyme activity in lung cytosol. However, 20alpha-HSD activity in kidney cytosol was little inhibited by 9,10-PQ or 1,2-NQ. Flavonoids such as quercetin, fisetin and kaempferol exhibited high inhibitory potencies for 20alpha-HSD activity in liver cytosol, whereas these flavonoids were poor inhibitors for the enzyme activity in kidney cytosol. It is likely that several diesel exhaust components and flavonoids augment the signaling of progesterone in the liver cells, by potently inhibiting 20alpha-HSD activity in mouse liver cytosol. The possibility that there are distinct enzymes catalyzing 20alpha-HSD activity in the non-reproductive tissues of male mice is also discussed.
authors.affiliation: Faculty of Education, Kumamoto University, 2-40-1, Kurokami, Kumamoto, 860-8555, Japan. hshimada@gpo.kumamoto-u.ac.jp
authors.forename: Hideaki
authors.initials: H
authors.lastname: Shimada
authors.forename: Misa
authors.initials: M
authors.lastname: Ohtaguro
authors.forename: Kazumi
authors.initials: K
authors.lastname: Miura
authors.forename: Yorishige
authors.initials: Y
authors.lastname: Imamura
mesh_terms: D043607:20-alpha-Hydroxysteroid Dehydrogenase / Q000737:chemistry* / Q000378:metabolism; D000818:Animals; D003600:Cytosol / Q000201:enzymology*; D004791:Enzyme Inhibitors / Q000737:chemistry; D005419:Flavonoids / Q000737:chemistry* / Q000494:pharmacology; D044948:Flavonols; D006863:Hydrogen-Ion Concentration; D044949:Kaempferols / Q000494:pharmacology; D008099:Liver / Q000201:enzymology*; D008297:Male; D051379:Mice; D008956:Models, Chemical; D011794:Quercetin / Q000494:pharmacology; D014018:Tissue Distribution; D001335:Vehicle Emissions
chemical_list: D004791:Enzyme Inhibitors; D005419:Flavonoids; D044948:Flavonols; D044949:Kaempferols; D001335:Vehicle Emissions; C006552:kaempferol; D011794:Quercetin; D043607:20-alpha-Hydroxysteroid Dehydrogenase; C017875:fisetin