Simple methods of quantifying oxidation products and antioxidant potential of low density lipoproteins.
OBJECTIVE
The present study describes new methods for the measurement of oxidation products and antioxidant potential of low density lipoproteins (LDL).


METHODS
LDL is isolated by precipitation with buffered heparin. The assay for LDL oxidation products (LDL-BDC) is based on determination of baseline levels of conjugated dienes (BDC) in lipids extracted from LDL. The assay for antioxidant potential of LDL (LDL-TRAP) is based on the ability of LDL to trap peroxyl radicals.


RESULTS
LDL-BDC was found to increase linearly over a range from 100 to 1750 microL, LDL-TRAP from 250 to 1750 microL of serum taken for precipitation. For LDL-BDC, the CV was 4.4% and 4.5% for within- and between-assay precision, respectively. For the LDL-TRAP, the CV was 8.1% and 8.7% for within- and between-assay precisions, respectively. Freezing of the serum (2 weeks at -70 degrees C) did not affect LDL-BDC or LDL-TRAP levels. A negative correlation was found to exist between the LDL-BDC and LDL-TRAP values. LDL-BDC and LDL-TRAP values were at the same level in both sexes. The LDL-BDC was found to increase with age. Short-term intervention with antioxidants increased LDL-TRAP substantially, but did not affect the LDL-BDC level.


CONCLUSIONS
These methods are fast and simple to perform, and can, therefore, be applied to clinical purposes.
Ahotupa
M
M
MCA Research Laboratory, Department of Physiology, University of Turku, Finland.
Ruutu
M
M
Mäntylä
E
E
D000293:Adolescent; D000328:Adult; D000368:Aged; D000975:Antioxidants / Q000032:analysis*; D001774:Blood Chemical Analysis / Q000379:methods*; D002021:Buffers; D011232:Chemical Precipitation; D008078:Cholesterol, LDL / Q000097:blood / Q000737:chemistry; D005069:Evaluation Studies as Topic; D005260:Female; D006493:Heparin; D006801:Humans; D008077:Lipoproteins, LDL / Q000097:blood* / Q000737:chemistry; D008297:Male; D008875:Middle Aged; D010084:Oxidation-Reduction
D000975:Antioxidants; D002021:Buffers; D008078:Cholesterol, LDL; D008077:Lipoproteins, LDL; D006493:Heparin