Characterization of antioxidants present in bitter tea (Ligustrum pedunculare).
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.
Chen
Zhen-Yu
ZY
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
Wong
Ivan Yuen Fan
IY
Leung
Magnolia Wing Shan
MW
He
Zhen-Dan
ZD
Huang
Yu
Y
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
D000975:Antioxidants; D016166:Free Radical Scavengers; D006027:Glycosides; D008077:Lipoproteins, LDL; C099252:oxidized low density lipoprotein; D024502:alpha-Tocopherol