title: Inhibition of inducible nitric oxide synthase and cyclooxygenase-2 expression by phenolic compounds from roots of Rhododendron mucronulatum.
abstract: The roots of Rhododendron mucronulatum Turzaninov have been used in Oriental traditional medicine for the treatment of dysuria, fever, increase of digestive activity and tonics in China and Korea. Activity guided isolation of the roots of Rhododendron mucronulatum Turzaninov has led to the isolation of three flavonoids, one flavan 3-ol and one proanthocyanidin. Chemical investigation of the 80% Me2 CO extract from the roots of Rhododendron mucronulatum led to the isolation and identification of five compounds: taxifolin (1), taxifolin 3-O-β-D-glucopyranoside (2), quercetin 3-O-α-L-arabinofuranoside (3), (-)-epicatechin (4), procyanidin B-3 (5). To investigate the antioxidative and antiinflammatory effects of these compounds, their 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities and the protein levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in LPS-stimulated HaCaT cells were also quantified by western blotting and their end products, nitric oxide (NO) and prostaglandin E2 (PGE2 ), respectively. Compounds (1-5) showed potent DPPH radical scavenging compared with positive controls (L-ascorbic acid). Also, compounds 1 and 2 dose-dependently inhibited the expressions of inflammatory mediators, NO and PGE2 , suggesting they are promising candidates as antiinflammatory agents.
authors.affiliation: College of Pharmacy, Chung Ang University, Seoul, 156-756, South Korea.
authors.forename: Sun Eun
authors.initials: SE
authors.lastname: Choi
authors.forename: Kwan Hee
authors.initials: KH
authors.lastname: Park
authors.forename: Byeong Hoon
authors.initials: BH
authors.lastname: Han
authors.forename: Mi Sook
authors.initials: MS
authors.lastname: Jeong
authors.forename: Seong Jun
authors.initials: SJ
authors.lastname: Seo
authors.forename: Do Ik
authors.initials: DI
authors.lastname: Lee
authors.forename: Seong Soo
authors.initials: SS
authors.lastname: Joo
authors.forename: Min Won
authors.initials: MW
authors.lastname: Lee
mesh_terms: D000893:Anti-Inflammatory Agents / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology; D001089:Arabinose / Q000031:analogs & derivatives / Q000494:pharmacology; D044946:Biflavonoids / Q000494:pharmacology; D002392:Catechin / Q000494:pharmacology; D002460:Cell Line; D051546:Cyclooxygenase 2 / Q000378:metabolism; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology*; D015232:Dinoprostone / Q000378:metabolism; D005960:Glucosides / Q000494:pharmacology; D006801:Humans; D009569:Nitric Oxide / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000037:antagonists & inhibitors*; D010936:Plant Extracts / Q000494:pharmacology*; D018517:Plant Roots / Q000737:chemistry; D044945:Proanthocyanidins / Q000494:pharmacology; D011794:Quercetin / Q000031:analogs & derivatives / Q000494:pharmacology; D029793:Rhododendron / Q000737:chemistry*
chemical_list: D000893:Anti-Inflammatory Agents; D000975:Antioxidants; D044946:Biflavonoids; D016861:Cyclooxygenase Inhibitors; D005960:Glucosides; D010936:Plant Extracts; D044945:Proanthocyanidins; C000590953:quercetin-3-O-alpha-arabinofuranoside; C067156:taxifolin-3-glucopyranoside; C479581:procyanidin B3; D009569:Nitric Oxide; D002392:Catechin; D011794:Quercetin; C003377:taxifolin; D001089:Arabinose; C496319:NOS2 protein, human; D052247:Nitric Oxide Synthase Type II; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D015232:Dinoprostone