Enzymatic O-methylation of flavanols changes lag time, propagation rate, and total oxidation during in vitro model triacylglycerol-rich lipoprotein oxidation.
3'-O-Methyl derivatives of flavan-3-ols, (+)-catechin (C), (-)-epicatechin (EC), and (-)-catechin gallate (CG) were prepared enzymatically. Hexanal (EC and CG family, 5 mmol/L) and conjugated diene (C and EC family, 0.25-10 mmol/L) formation following CuSO4-mediated triacylglycerol-rich lipoprotein oxidation was measured. All EC and CG compounds significantly reduced hexanal formation (p < 0.02). O-Methylation improved the ability of CG (more polar) while reducing the ability of EC (less polar) to limit hexanal formation. 3'-O-methyl EC was 18% (p < 0.001) and 4'-O-methyl 65% (p < 0.001) less able than EC to suppress hexanal formation. At >1 micromol/L all EC and C compounds significantly increased lag time. Parent compounds were more effective (> 4-fold increase) than metabolites (1.5-fold increase). Parent compounds did not influence propagation rate (DeltaOD/min). At >1 mmol/L O-methylated EC and C reduced propagation by 20-40% (p < 0.01). Notably, at 0.25 mmol/L O-methylated EC and C increased propagation rates 22% (p < 0.01) despite prolonging lag time.
Yu
Jun
J
Department of Horticultural Sciences, Texas A&M University, College Station, Texas 77843, USA.
Smith
Gabe
G
Gross
Heidrun B
HB
Hansen
Robert J
RJ
Levenberg
John
J
Walzem
Rosemary L
RL
D015243:Cholesterol, VLDL / Q000737:chemistry / Q000378:metabolism*; D005419:Flavonoids / Q000737:chemistry / Q000378:metabolism*; D008745:Methylation; D008954:Models, Biological; D015394:Molecular Structure; D010084:Oxidation-Reduction; D013997:Time Factors; D014280:Triglycerides / Q000737:chemistry / Q000378:metabolism*
D015243:Cholesterol, VLDL; D005419:Flavonoids; D014280:Triglycerides