title: The antioxidative effect of icariin in human erythrocytes against free-radical-induced haemolysis.
abstract: Icariin (2-(4'-methoxyl phenyl)-3-rhamnosido-5-hydroxyl-7-glucosido-8-(3'-methyl-2-butylenyl)-4-chromanone) is the major component in Herba Epimedii used in traditional Chinese medicine for the treatment of atherosclerosis. This work focuses on the antioxidative effect of icariin on free-radical-induced haemolysis of human erythrocytes, in which the initial free radical derives from the decomposition of 2,2'-azobis(2-amidinopropane hydrochloride) (AAPH) at physiological temperature. To reveal the structure-activity relationship of icariin, the antioxidant effects of two structural analogues of icariin, acacetin (2-(4'-methoxylphenyl)-5,7-dihydroxylchromone) and norwogonin (2-phenyl-5,7,8-trihydroxylchromone), on the same experimental system were examined as well. It was found that all these chromone derivatives (Chm-OHs) dose-dependently protected human erythrocytes against free-radical-induced haemolysis. The order of antioxidative activity was norwogonin > acacetin > icariin by the analysis of the relationship between the concentration of Chm-OHs and the prolongation percentage of the lag time of haemolysis (PP%). It was also proved that the phenyl hydroxyl group attached to the chromone ring at 7-position cannot trap the free radical. On the contrary, phenyl hydroxyl groups at the 5- and 8-position in norwogonin made it a significant antioxidant in AAPH-induced haemolysis. The more hydroxyl groups attached to the chromone ring, the higher the antioxidative activity in protecting erythrocytes against free-radical-induced peroxidation.
authors.affiliation: Department of Organic Chemistry, College of Chemistry, Jilin University, No. 2519 Jiefang Road, Changchun 130021, China. zaiqun-liu@jlu.edu.cn
authors.forename: Zai-Qun
authors.initials: ZQ
authors.lastname: Liu
authors.forename: Xu-Yang
authors.initials: XY
authors.lastname: Luo
authors.forename: Yun-Xiu
authors.initials: YX
authors.lastname: Sun
authors.forename: Wei
authors.initials: W
authors.lastname: Wu
authors.forename: Chun-Ming
authors.initials: CM
authors.lastname: Liu
authors.forename: Zhi-Qiang
authors.initials: ZQ
authors.lastname: Liu
authors.forename: Shu-Ying
authors.initials: SY
authors.lastname: Liu
mesh_terms: D000975:Antioxidants / Q000737:chemistry / Q000494:pharmacology*; D004912:Erythrocytes / Q000187:drug effects* / Q000378:metabolism; D005419:Flavonoids / Q000737:chemistry / Q000494:pharmacology*; D005609:Free Radicals / Q000378:metabolism*; D006461:Hemolysis / Q000187:drug effects* / Q000502:physiology; D006801:Humans
chemical_list: D000975:Antioxidants; D005419:Flavonoids; D005609:Free Radicals; C056599:icariin