Tocopherols and carotenes are differently distributed in subfractions of high-density lipoprotein

Area of Science:

• Lipid biochemistry
• Nutritional science
• Cardiovascular research

Background:

• High-density lipoprotein (HDL) plays a crucial role in reverse cholesterol transport.
• HDL composition, including apolipoprotein E (apo E) content, can influence its function.
• Antioxidants like tocopherols and carotenes are carried by lipoproteins and may contribute to HDL's protective effects.

Purpose of the Study:

• To investigate the differential distribution of antioxidants between apo E-rich and apo E-poor HDL subfractions.
• To explore the relationship between HDL cholesterol levels and the proportion of apo E-rich HDL in carrying alpha-tocopherol.

Main Methods:

• Isolation of apo E-rich and apo E-poor HDL fractions using heparin-Sepharose affinity chromatography from plasma of healthy men.
• Quantification of alpha- and gamma-tocopherol and alpha- and beta-carotene content in isolated HDL subfractions on a cholesterol basis.
• Correlation analysis between plasma HDL cholesterol concentrations and the contribution of apo E-rich HDL to total HDL alpha-tocopherol.

Main Results:

• The apo E-poor HDL fraction exhibited a higher concentration of alpha- and gamma-tocopherol compared to the apo E-rich fraction.
• Conversely, the apo E-poor HDL fraction contained less alpha- and beta-carotene than the apo E-rich fraction.
• A strong negative correlation was observed between plasma HDL cholesterol concentrations and the percentage of apo E-rich HDL subfraction contributing to total HDL alpha-tocopherol.

Conclusions:

• HDL subfractions display distinct profiles of antioxidant enrichment.
• The apo E content of HDL significantly influences its associated tocopherol and carotene levels.
• Plasma HDL cholesterol levels are closely linked to the apo E-rich HDL subfraction's role in alpha-tocopherol transport.