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Inhibition of Inducible Nitric Oxide Synthase and Cyclooxygenase‐2 Expression by Phenolic Compounds from Roots of Rhododendron mucronulatum
Author(s) -
Choi Sun Eun,
Park Kwan Hee,
Han Byeong Hoon,
Jeong Mi Sook,
Seo Seong Jun,
Lee Do Ik,
Joo Seong Soo,
Lee Min Won
Publication year - 2011
Publication title -
phytotherapy research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.019
H-Index - 129
eISSN - 1099-1573
pISSN - 0951-418X
DOI - 10.1002/ptr.3376
Subject(s) - taxifolin , dpph , nitric oxide , chemistry , quercetin , nitric oxide synthase , cyclooxygenase , phenylethanoid , traditional medicine , biochemistry , pharmacology , antioxidant , enzyme , stereochemistry , glycoside , biology , medicine , organic chemistry
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% Me 2 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 E 2 (PGE 2 ), 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 PGE 2 , suggesting they are promising candidates as antiinflammatory agents. Copyright © 2011 John Wiley & Sons, Ltd.