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GCG‐Rich Tea Catechins are Effective in Lowering Cholesterol and Triglyceride Concentrations in Hyperlipidemic Rats
Author(s) -
Lee Sang Min,
Kim Chae Wook,
Kim Jung Kee,
Shin Hyun Jung,
Baik Joo Hyun
Publication year - 2008
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/s11745-008-3167-4
Subject(s) - clinical chemistry , lipidology , triglyceride , food science , chemistry , cholesterol , hyperlipidemia , ldl cholesterol , medicine , biochemistry , endocrinology , diabetes mellitus
The (−)‐gallocatechin gallate (GCG) concentration in some tea beverages can account for as much as 50% of the total catechins, as a result of sterilization. The present study aims to examine the effects of GCG‐rich tea catechins on hyperlipidemic rats and the mechanisms associated with regulating cholesterol metabolism in the liver. By performing heat epimerization of (−)‐epigallocatechin gallate (EGCG), we manufactured a mixture of catechins that had a GCG content of approximately 50% (w/w). In sucrose‐rich diet‐induced hyperlipidemic rats, the GCG‐rich tea catechins exhibited strong activity in reducing plasma cholesterol and triglyceride concentrations. Furthermore, the hepatic cholesterol and triglyceride concentrations that had increased as a result of the sucrose‐rich diet were reduced due to GCG‐rich tea catechins consumption. In order to investigate the hyperlipidemic mechanism of GCG‐rich tea catechins, we examined the hepatic expressions of LDL receptor and HMG‐CoA reductase in hyperlipidemic rats. We further evaluated the action of purified GCG on LDL receptor activity, which is a key contributor to the regulation of cholesterol concentrations. We found that purified GCG increased LDL receptor protein level and activity to a greater extent than EGCG. In conclusion, our study indicates that GCG‐rich tea catechins in tea beverages may be effective in preventing hyperlipidemia by lowering plasma and hepatic cholesterol concentrations.