Modulation of cholesterol metabolism by the green tea polyphenol (-)-epigallocatechin gallate in cultured human liver (HepG2) cells.
Epidemiological and animal studies have found that green tea is associated with lower plasma cholesterol. This study aimed to further elucidate how green tea modulates cholesterol metabolism. When HepG2 cells were incubated with the main green tea constituents, the catechins, epigallocatechin gallate (EGCG) was the only catechin to increase LDL receptor binding activity (3-fold) and protein (2.5-fold) above controls. EGCG increased the conversion of sterol regulatory element binding protein-1 (SREBP-1) to its active form (+56%) and lowered the cellular cholesterol concentration (-28%). At 50 microM, EGCG significantly lowered cellular cholesterol synthesis, explaining the reduction in cellular cholesterol. At 200 microM EGCG, cholesterol synthesis was significantly increased even though cellular cholesterol was lower, but there was a significant increase seen in medium cholesterol. This indicates that, at 200 microM, EGCG increases cellular cholesterol efflux. This study provides mechanisms by which green tea modulates cholesterol metabolism and indicates that EGCG might be its active constituent.
Bursill
Christina A
CA
Wellcome Trust Centre of Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, United Kingdom.
Roach
Paul D
PD
D028241:Camellia sinensis / Q000737:chemistry*; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D045744:Cell Line, Tumor; D002635:Chenodeoxycholic Acid; D002784:Cholesterol / Q000032:analysis / Q000096:biosynthesis / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007810:Lanosterol / Q000032:analysis; D008099:Liver / Q000187:drug effects* / Q000378:metabolism*; D018515:Plant Leaves / Q000737:chemistry; D011973:Receptors, LDL / Q000187:drug effects / Q000378:metabolism; D051780:Sterol Regulatory Element Binding Protein 1 / Q000032:analysis
D011973:Receptors, LDL; C497387:SREBF1 protein, human; D051780:Sterol Regulatory Element Binding Protein 1; D002635:Chenodeoxycholic Acid; D007810:Lanosterol; D002392:Catechin; D002784:Cholesterol; C045651:epigallocatechin gallate