چكيده لاتين :
The oxidative modification of low density lipoprotein (LDL) may play an important role
in atherogenesis. Antioxidants that can prevent LDL oxidation may act as antiatherogens. Our
understanding ofthe mechanism ofLDLoxidation and factors that determine its susceptibility to
oxidation is still incomplete. Copper is a candidate for oxidizing LDL in atherosclerotic lesions.
The binding of copper ions to LDL is usually thought to be a prerequisite for LDL oxidation by
copper. Therefore we investigated the effect ofa-tocopherol (as a major fat soluble antioxidant)
on copper bound to LDL and furthermore effect of this binding on the susceptibility ofLDL to
oxidative modification.
In this study LDL was isolated from EDTA-plasma (1 mg EDTA/ml blood) by
ultracentrifugation using a single-step discontinuous gradient. Then a-tocopherol was added to
LDL and incubated for I hat 37° C. The oxidation rate ofLDL was estimated by thiobarbitoric
acid reactive substances (TBARS) after CuS04 addition. Finally, the effect of a-tocopherol on
formation ofLDL-copper complex by gel filtration was studied.
Our results showed that a-tocopherol (dose dependently) suppressed the formation of
TBARS and LDL-copper complex. The a-tocopherol with concentrations of 10, 50 and 100
IlM reduced susceptibility of LDL to oxidative modification approximately by 2, 13 and 21
percent, respectively. Furthermore, addition of a-tocopherol to the LDL and CuS04 mixture
containing before hand prevented the formation of LDL-copper complex, approximately by
30 percent.
In conclusion we found that a-tocopherol with inhibition of copper binding to LDL may
decrease the susceptibility ofLDL oxidation to this ion and thus could playa role in prevention
ofatherosclerosis.
