Both HDL₃ and HDL₂ Exert a Powerful Anti-Oxidative and Protective Effect against Acceleration of Oxidative Modification of LDL by Ascorbic Acid

Abstract

The objective of the present study was to establish whether high-density lipo-protein 3 (HDL₃) or high-density lipoprotein 2 (HDL₂) might show an anti-oxidative effect on the acceleration of the oxidative modification of low-density lipoprotein(LDL) by ascorbic acid from measurement of the agarose gel electrophoretic mobility of LDL. LDL was incu-bated without adding transitional-metal ions for 48 or 96h in phosphate-buffered saline (PBS) alone, with ascorbic acid (20μg/mL), or with both ascorbic acid (20μg/mL) and HDL₃ (200μg protein/mL). The LDL autoxidation occurred in PBS alone. Although ascor-bic acid significantly suppressed oxidative modification of LDL after incubation for 48h, the opposite was true after 96h. However, since the anti-oxidative ability of HDL₂ shows a weaker tendency than that of HDL₃, both HDL₃ and HDL₂ significantly inhibited this accel-eration of oxidative modification of LDL by ascorbic acid as assessed by electrophoretic mobility. If there is an augmented oxidative modification of LDL due to ascorbic acid in vivo, HDL₃ or HDL₂ may thus have an important role in inhibiting this ascorbic acid-accelerated oxidation of LDL.