title: Characterization of antioxidants present in bitter tea (Ligustrum pedunculare).
abstract: The present study examined the antioxidants present in bitter tea (Ligustrum pedunculare). It was found that the crude glycoside fraction strongly protected human low-density lipoprotein (LDL) from oxidation. Further column chromatography led to purification of eight phenylethanoid or monoterpene glycosides: lipedoside A-I, lipedoside A-II, lipedoside B-I, lipedoside B-III, lipedoside B-V, lipedoside B-VI, osmanthuside B, and anatolioside. It was found that lipedoside A-I, lipedoside A-II, lipedoside B-V, and lipedoside B-VI were protective, whereas the other four compounds did not protect human LDL from Cu(2+)-medicated oxidation. Lipedoside A-I, lipedoside A-II, lipedoside B-V, and lipedoside B-VI also had a scavenging effect on 2,2-diphenyl-1-picrylhydrazyl free radical (DPPH), comparable to that of alpha-tocopherol. The inhibitory effect of these four phenylethanoid or monoterpene glycosides on oxidation of human LDL and alpha-tocopherol was dose-dependent at concentrations of 5-40 microM. The present results demonstrate that bitter tea as a beverage contains effective antioxidants that may have benefits similar to those of green tea in terms of antioxidant activity.
authors.affiliation: Food and Nutritional Science Programme, Department of Biochemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, People's Republic of China. zhenyuchen@cuhk.edu.hk
authors.forename: Zhen-Yu
authors.initials: ZY
authors.lastname: Chen
authors.forename: Ivan Yuen Fan
authors.initials: IY
authors.lastname: Wong
authors.forename: Magnolia Wing Shan
authors.initials: MW
authors.lastname: Leung
authors.forename: Zhen-Dan
authors.initials: ZD
authors.lastname: He
authors.forename: Yu
authors.initials: Y
authors.lastname: Huang
mesh_terms: D000975:Antioxidants / Q000032:analysis* / Q000737:chemistry; D001628:Beverages / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D016166:Free Radical Scavengers / Q000494:pharmacology; D006027:Glycosides / Q000302:isolation & purification / Q000494:pharmacology; D006801:Humans; D031659:Ligustrum / Q000737:chemistry*; D015227:Lipid Peroxidation / Q000187:drug effects; D008077:Lipoproteins, LDL / Q000737:chemistry; D010084:Oxidation-Reduction; D024502:alpha-Tocopherol / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D016166:Free Radical Scavengers; D006027:Glycosides; D008077:Lipoproteins, LDL; C099252:oxidized low density lipoprotein; D024502:alpha-Tocopherol