title: Nobiletin metabolite, 3',4'-dihydroxy-5,6,7,8-tetramethoxyflavone, inhibits LDL oxidation and down-regulates scavenger receptor expression and activity in THP-1 cells.
abstract: There is accumulating evidence that LDL oxidation is essential for atherogenesis and antioxidants that prevent oxidation may either decelerate or reduce atherogenesis. Current study focused on the effect and mechanism of 3',4'-dihydroxy-5,6,7,8-tetramethoxyflavone (DTF), a major metabolite of nobiletin (NOB, a citrus polymethoxylated flavone) on atherogenesis. We found DTF had stronger inhibitory activity than alpha-tocopherol on inhibiting Cu2+-mediated LDL oxidation measured by thiobarbituric acid-reactive substances assay (TBARS), conjugated diene formation and electrophoretic mobility. Monocyte-to-macrophage differentiation plays a vital role in early atherogenesis. DTF (10-20 microM) dose-dependently attenuated differentiation along with the reduced gene expression of scavenger receptors, CD36 and SR-A, in both PMA- and oxidized low-density lipoprotein (oxLDL)-stimulated THP-1 monocytes. Furthermore, DTF treatment of monocytes and macrophages led to reduction of fluorescent DiI-acLDL and DiI-oxLDL uptake. In conclusion, at least three mechanisms are at work in parallel: DTF reduces LDL oxidation, attenuates monocyte differentiation into macrophage and blunts uptake of modified LDL by macrophage. The effect is different from that of NOB, from which DTF is derived. This study thus significantly enhanced our understanding on how DTF may be beneficial against atherogenesis.
authors.affiliation: Department of Biotechnology, Chia-Nan University of Pharmacy and Science, Tainan 717, Taiwan.
authors.forename: Ya-Hsuan
authors.initials: YH
authors.lastname: Lo
authors.forename: Min-Hsiung
authors.initials: MH
authors.lastname: Pan
authors.forename: Shiming
authors.initials: S
authors.lastname: Li
authors.forename: Jui-Hung
authors.initials: JH
authors.lastname: Yen
authors.forename: Mei-Chun
authors.initials: MC
authors.lastname: Kou
authors.forename: Chi-Tang
authors.initials: CT
authors.lastname: Ho
authors.forename: Ming-Jiuan
authors.initials: MJ
authors.lastname: Wu
mesh_terms: D000818:Animals; D039481:CD11b Antigen / Q000235:genetics / Q000378:metabolism; D018955:CD36 Antigens / Q000235:genetics / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D015536:Down-Regulation; D047309:Flavones / Q000494:pharmacology*; D005434:Flow Cytometry; D015227:Lipid Peroxidation / Q000187:drug effects; D008077:Lipoproteins, LDL / Q000737:chemistry / Q000378:metabolism*; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D009000:Monocytes / Q000187:drug effects* / Q000378:metabolism; D010084:Oxidation-Reduction; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051117:Scavenger Receptors, Class A / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051127:Scavenger Receptors, Class E / Q000235:genetics / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism
chemical_list: C547849:3',4'-dihydroxy-5,6,7,8-tetramethoxyflavone; D039481:CD11b Antigen; D018955:CD36 Antigens; D047309:Flavones; D008077:Lipoproteins, LDL; C495138:Olr1 protein, mouse; D012333:RNA, Messenger; D051117:Scavenger Receptors, Class A; D051127:Scavenger Receptors, Class E; D017392:Thiobarbituric Acid Reactive Substances; C099252:oxidized low density lipoprotein; C008661:nobiletin; D013755:Tetradecanoylphorbol Acetate