Protection of endogenous vitamin E and beta-carotene by aminoguanidine upon oxidation of human low-density lipoproteins by (OH)-O-center dot/O-2(center dot-)
D. Lisfi et al., Protection of endogenous vitamin E and beta-carotene by aminoguanidine upon oxidation of human low-density lipoproteins by (OH)-O-center dot/O-2(center dot-), RADIAT RES, 153(5), 2000, pp. 497-507
This study was designed to evaluate the antioxidant effect of aminoguanidin
e toward human low-density lipoproteins (LDLs) initiated by oxygenated free
radicals ((OH)-O-./O-2(.-)) generated by gamma radiolysis, Initial radioly
tic yields related to the markers of lipid peroxidation [i.e. decrease in e
ndogenous alpha-tocopherol and beta-carotene, formation of thiobarbituric a
cid-reactive substances (TBARS) and conjugated dienes] were determined in 3
g liter(-1) LDLs (expressed as total LDL concentration) in the absence and
presence of 10 different concentrations of aminoguanidine (from 0.04 to 5
mmol liter-L). Fluorescence and relative electrophoretic mobility of oxidiz
ed LDLs were also studied as markers that indirectly reflect the attack of
the protein moiety of LDLs (namely apolipoprotein B), Our data clearly show
ed the inhibitory effect of aminoguanidine on lipid peroxidation induced in
LDLs by (OH)-O-./O-2(.-) in a concentration-dependent manner. This effect
probably resulted from a scavenging activity of aminoguanidine toward (OH)-
O-.. In contrast, aminoguanidine did not appear to react significantly with
O-2(.-), which resulted in a poor residual lipid peroxidation, Our data le
d us to determine an optimum [aminoguanidine]/[LDL] ratio ranging from 250
to 500 to obtain the best in vitro protection of LDLs under our experimenta
l conditions. It is also of great interest that aminoguanidine was able to
protect endogenous ol-tocopherol and beta-carotene of LDLs upon (OH)-O-./O-
2(.-)-induced oxidation, (C) 2000 by Radiation Research Society.