title: A rapid method for separation of plasma low and high density lipoproteins for tocopherol and carotenoid analyses.
abstract: Ultracentrifugation (UC) is the method most often employed for separation and quantification of lipoproteins. Because this procedure requires expensive laboratory equipment, a large volume of fresh sample and an inordinate amount of time, it may not be ideal for routine clinical/experimental use. The aim of the current study was to evaluate a method which combines selective precipitation (HDL-P) and immunoseparation (LDL-I) for the rapid and reliable isolation of high density lipoproteins (HDL) and low density lipoproteins (LDL) specifically for vitamin E and carotenoid determination within these fractions. Cholesterol and triacylgylcerol concentrations within the HDL and LDL were also determined to enable expression of vitamin E and carotenoid concentrations per gram of lipid. Isolation of lipoproteins by UC was used as the reference method (HDL-UC/LDL-UC). There were no significant differences between methods for alpha- and gamma-tocopherol in LDL and HDL. Carotenoids measured in HDL and LDL were comparable between the methods. The exception was higher lutein/zeaxanthin concentration in HDL-P and LDL-I compared to HDL-UC and LDL-UC, respectively. Additionally, lycopene concentration was significantly lower in LDL-I compared to LDL-UC. In comparing vitamin E and carotenoid values in lipoproteins separated from fresh and frozen plasma by the direct method, there was no difference in alpha-tocopherol or the majority of carotenoids measured. In conclusion, a combination of selective precipitation and immunoseparation of fresh or frozen plasma for subsequent alpha- and gamma-tocopherol analyses provides an accurate and reliable alternative to lipoprotein separation by UC. Additionally, carotenoid concentrations in HDL separated by selective precipitation and analyses of alpha- and beta-carotenes and beta-cryptoxanthin in LDL separated by immunoseparation are also reliable, while lycopene and lutein/zeaxanthin concentrations in LDL-I are not readily comparable to LDL-UC.
authors: Department of Nutritional Sciences, University of Connecticut, Storrs 06269, USA.
authors: S
authors: S
authors: Vogel
authors: J H
authors: JH
authors: Contois
authors: S C
authors: SC
authors: Couch
authors: C J
authors: CJ
authors: Lammi-Keefe
mesh_terms: D001800:Blood Specimen Collection / Q000379:methods; D002338:Carotenoids / Q000032:analysis / Q000097:blood*; D011232:Chemical Precipitation; D002784:Cholesterol / Q000097:blood; D006801:Humans; D007163:Immunosorbent Techniques; D008075:Lipoproteins, HDL / Q000097:blood* / Q000302:isolation & purification; D008077:Lipoproteins, LDL / Q000097:blood* / Q000302:isolation & purification; D012016:Reference Values; D014280:Triglycerides / Q000097:blood; D014461:Ultracentrifugation / Q000379:methods; D014810:Vitamin E / Q000032:analysis / Q000097:blood*
chemical_list: D008075:Lipoproteins, HDL; D008077:Lipoproteins, LDL; D014280:Triglycerides; D014810:Vitamin E; D002338:Carotenoids; D002784:Cholesterol