Abstract:

Abstract: Establish a liquid chromatography tandem mass spectrometry (LC-MS/MS) method to quantify sialic acid (N-acetylneuraminic acid, NANA) from human lipoproteins, and investigate the content difference of liproprotein NANA between diabetic (average age 51.6 years) and healthy participants (average age 19.3 years). Sialic acid from lipoprotein samples were released by acetic acid (pH=2) at 80 °C for 2 h and analyzed by the optimized LC-MS/MS directly after high speed centrifugation and filtration. Results demonstrated that the limit of detection and quantification of NANA was 45.6 and 145.3 pg, respectively, under negative mode. The linear range was 50-1600 ng/mL for NANA and the correlation coefficient (R2) was greater than 0.999; the levels of NANA in the plasma of type II diabetic and healthy participants were 544.5 ± 113.1 and 370.9 ± 38.8 mg/L, respectively; and the levels of NANA in VLDL, LDL, HDL2 and HDL3 from type II diabetic and healthy participant were 2.46 ± 0.15, 2.44 ± 0.12, 1.78 ± 0.15, 1.38 ± 0.11 and 3.68 ± 0.19, 3.89 ± 0.17, 3.46 ± 0.20, 2.35 ± 0.17 μg/mg protein, respectively. Therefore, the established LC-MS/MS method for detection of NANA is reproducible and time saving; The sialic acid levels of lipoproteins from type II diabetic are markedly reduced compared to those of healthy ones (P＜0.01), which maybe induced by the long term oxidative stress in diabetics and the age difference of the two groups (51.6 vs 19.3).