title: Effects of kaempferol and myricetin on inducible nitric oxide synthase expression and nitric oxide production in rats.
abstract: When administered as drugs or consumed as food components, polyphenolic compounds synthesized in plants interfere with intracellular signal transduction pathways, including pathways of nitric oxide synthase expression. However, effects of these compounds in vivo do not always correlate with nitric oxide synthase-inhibiting activities revealed in experiments with cultured cells. The initial goal of this work was to compare effects of flavonoids kaempferol and myricetin on inducible nitric oxide synthase mRNA and protein expression monitored by real-time RT-PCR and immunohistochemistry and to evaluate the impact of these effects on nitric oxide production in rat organs measured by means of electron paramagnetic resonance spectroscopy. Kaempferol and myricetin attenuated the lipopolysaccharide-induced outburst of inducible nitric oxide synthase gene expression; kaempferol also significantly decreased the lipopolysaccharide-induced outburst of inducible nitric oxide synthase protein expression in the liver. Myricetin decreased nitric oxide production in intact rat liver. Kaempferol did not decrease nitric oxide production neither in intact rats nor in the lipopolysaccharide-treated animals. Kaempferol even enhanced the lipopolysaccharide-induced increase of nitric oxide production in blood. Myricetin did not interfere with lipopolysaccharide effects. As both kaempferol and myricetin are known as inhibitors of inducible nitric oxide synthase expression, our results suggest that modifications of nitric oxide level in tissues by these compounds cannot be predicted from data about its effects on nitric oxide synthase expression or activity.
authors.affiliation: Latvian Institute of Organic Synthesis, Riga, Latvia.
authors.forename: Evita
authors.initials: E
authors.lastname: Rostoka
authors.forename: Larisa
authors.initials: L
authors.lastname: Baumane
authors.forename: Sergejs
authors.initials: S
authors.lastname: Isajevs
authors.forename: Aija
authors.initials: A
authors.lastname: Line
authors.forename: Maija
authors.initials: M
authors.lastname: Dzintare
authors.forename: Darja
authors.initials: D
authors.lastname: Svirina
authors.forename: Jelena
authors.initials: J
authors.lastname: Sharipova
authors.forename: Karina
authors.initials: K
authors.lastname: Silina
authors.forename: Ivars
authors.initials: I
authors.lastname: Kalvinsh
authors.forename: Nikolajs
authors.initials: N
authors.lastname: Sjakste
mesh_terms: D000818:Animals; D004578:Electron Spin Resonance Spectroscopy; D005419:Flavonoids / Q000494:pharmacology*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D044949:Kaempferols / Q000494:pharmacology*; D008070:Lipopolysaccharides; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009569:Nitric Oxide / Q000096:biosynthesis*; D052247:Nitric Oxide Synthase Type II / Q000235:genetics*; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D005419:Flavonoids; D044949:Kaempferols; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D009569:Nitric Oxide; C006552:kaempferol; C040015:myricetin; D052247:Nitric Oxide Synthase Type II