| Summary: | 碩士 === 國立臺灣大學 === 生化學研究所 === 84 === Previous studies had revealed that PUFA is more susceptible to oxidation than
saturated fatty acids, but the studies about the effect of cholesterol on LDL
oxidation is still not clear.
In order to explore the effects of n-3 PUFA and cholesterol on LDL oxidation in
vitro, male hamsters about 80g were divided into four groups and fed
semisynthetic diets containing 15% protein for 3 weeks. The fat of the
experimental diet is a mixture of coconut oil, soybean oil and fish oil by different
propotion and P/S is equal to 1. When hamsters were sacrified, we used
ultracentrifuge isolate lipoproteins. After dialyzed against PBS, LDL was
oxidized with 5 mM Cu2+ in vitro. Besides with the formation of TBARS,
conjugated diene and electrophoretic mobility assay to test the susceptibility of
LDL to Cu2+-catalyzed oxidation, we also analyze the content of a-tocopherol
and composition of fatty acid of LDL.
No matter with or without cholesterol supplementation in the diets, the n-3
PUFA content in the LDL of n-3 PUFA group is obviously higher than that in
the LDL of the n-6 PUFA group, but the linoleic acid (C 18:2) content of the
LDL of n-3 PUFA group is obviously lower than that of n-6 PUFA group.
Besides, the a-tocopherol content of LDL reveals that the LDL of n-6
PUFA+0.1%C group has the highest content of a-tocopherol, the next is the
LDL of n-6 PUFA group and the LDL of n-3 PUFA group has the lowest
content of a-tocopherol. Thus the results suggest that the LDL of n-3 PUFA
group is more susceptible to oxidation than that of n-6 PUFA group is due to
the change of fatty acid composition or the content of a-tocopherol of LDL
reduced in LDL of n-3 PUFA fed hamsters. The supplementation of dietary
cholesterol may result in change of the a-tocopherol content in LDL or the
cholesterol may function as antioxidant .
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