title: Inhibitory activity of quercetin and its metabolite on lipopolysaccharide-induced activation of macrophage U937 cells.
abstract: The potential of quercetin and its metabolite 3-O-methyl quercetin in inhibiting lipopolysaccharide (LPS)-mediated activation of macrophage U937 cells was investigated. Cells were pre-incubated for different periods with 100 ng/mL phorbol myristate acetate (PMA), and later with LPS and quercetin or 3-O-methyl quercetin (30 microM). Later, the supernatant of each cell culture was assessed for catalase activity, nitric oxide, and the production of tumour necrosis factor-alpha (TNF-alpha), interleukin 6 (IL-6), and interleukin 1 (IL-1). The results showed that when the cells were incubated with LPS, there were elevations in the levels of all the markers over the cells not incubated with LPS (P < 0.05). For the cells that were incubated with LPS, there were significant differences between the various cells when they were pre-incubated with PMA for various periods (P < 0.05). However, greatest production of the markers was attained when the cells were pre-treated with PMA for 48 h. Both quercetin and 3-O-methyl quercetin (at 30 mM) reduced the levels of all the markers with 3-O-methyl quercetin possessing more inhibitory potential (P < 0.05). This suggests that the flavonoids possessed significant immunomodulatory activities which depend on methylation especially at position 3.
authors.affiliation: Department of Chemical Sciences, Biochemistry Division, Niger Delta University, PMB 71, Wilberforce Island, Bayelsa State, Nigeria. tebebuddy@yahoo.com
authors.forename: Tebekeme
authors.initials: T
authors.lastname: Okoko
authors.forename: Ibiba Felix
authors.initials: IF
authors.lastname: Oruambo
mesh_terms: D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008262:Macrophage Activation / Q000187:drug effects*; D011794:Quercetin / Q000031:analogs & derivatives* / Q000494:pharmacology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D020298:U937 Cells
chemical_list: D008070:Lipopolysaccharides; C047368:3-methylquercetin; D011794:Quercetin; D013755:Tetradecanoylphorbol Acetate