Homogeneous assay for measuring low-density lipoprotein cholesterol in serum with triblock copolymer and α-cyclodextrin sulfate

Abstract

We have developed a fully automated method for measuring LDL-cholesterol (LDL-C) in human serum without the need for prior separation, using a nonionic surfactant, polyoxyethylene–polyoxypropylene block copolyether (POE-POP), and a sodium salt of sulfated cyclic maltohexaose, α-cyclodextrin sulfate. Of the surfactants tested, POE-POP with a higher molecular mass of the POP block and a greater hydrophobicity reduced the reactivity of cholesterol in lipoprotein fractions; the reactivity in descending order was LDL ≫ VLDL > chylomicron ≈ HDL. Gel filtration chromatographic studies revealed that POE-POP removed lipids selectively from the LDL fraction and allowed them to participate in the cholesterol esterase–cholesterol oxidase coupling reaction system. By contrast, α-cyclodextrin sulfate reduced the reactivity of cholesterol, especially in chylomicrons and VLDL. A combination of POE-POP with α-cyclodextrin sulfate provided the required selectivity for the determination of LDL-C in serum in the presence of magnesium ions and a small amount of dextran sulfate without precipitating lipoprotein aggregates. There was a good correlation between the results of LDL-C assayed by the proposed method and the beta-quantification reference method involving 161 sera with triglyceride concentrations ranging from 0.3 to 22.6 mmol/L.

Efficacy and safety of pemafibrate (K-877), a selective peroxisome proliferator-activated receptor α modulator, in patients with dyslipidemia: Results from a 24-week, randomized, double blind, active-controlled, phase 3 trial

“…The homogeneous assay uses acyclodextrin sulfate and a nonionic surfactant (polyoxyethylene-polyoxypropylene block copolymer) to block the enzymatic reaction of cholesterol in chylomicrons and VLDL and selectively solubilize LDL without affecting HDL, respectively. 21,22 Non-HDL-C was calculated by subtracting HDL-C from total cholesterol (TC). Fibroblast growth factor 21 (FGF21) level was measured using the enzyme-linked immunosorbent assay with HUMAN FGF21 ELISA (BioVendor, Czech Republic).…”

Omega-3 Fatty Acids Improve Lipid Metabolism and Inflammatory Markers in Patients with Heart Failure Undergoing Exercise Training

“…HDL-cholesterol (HDL-C) was measured by homogeneous reagent [27] and low-density lipoprotein-cholesterol (LDL-C) was estimated according to the Friedewald formula for triglyceride levels < 4.52 mmol/L [28] . For samples which were found to contain levels of triglyceride > 4.52 mmol/L, LDL-C was directly measured by the homogeneous LDL-C method (Labest -Lagoa Santa -MG, Brazil) [29] . In order to minimize the variation, the direct LDL-C method was used for all serum samples of the patients who had triglyceride > 4.52 mmol/L, i.e., samples collected before and after n-3 PUFA treatment.…”

Lipid Profile of a Population of Jacqueville, Consumer of Palm Oil in Southern Côte d’Ivoire

“…We dosed HDL-C using method Precipitation with Phosphotungstic acid method in presence of Magnesium ions [20]. The dose of LDL Cholesterol (C-LDL) was performed blocking lipoproteins other than LDL method [21]. Furthermore, only the cholesterol associated to LDL was dosed by Enzymatic Reaction.…”