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Analysis of O-Acetylated Sialic Acids in Dried Blood Spots

Zhang, Qiwei, Wang, Yawei, Zheng, Qi, Li, Jianjun
Analytical chemistry 2019 v.91 no.4 pp. 2744-2751
Carassius, acids, blood sampling, blood serum, derivatization, gangliosides, glycoconjugates, liquid chromatography, mass spectrometry, moieties, neoplasms, neuraminic acid, polysaccharides, sialic acids, storage time
Sialic acid is a family of N- and O-substitutions of neuraminic acid. Plasma or serum sialic acid has been established as a potential disease marker. For example, the presence of 9-O-acetyl on the sialic acid of some glycans and glycoconjugates (e.g., 9-O-acetyl GD3 ganglioside) could be related to cancer occurrence. A variety of assays are available to measure serum or plasma sialic acid; however, sample preparation and storage can alter the O-acetylation profile due to the loss of O-acetyl groups and/or the migration of O-acetyl groups. Herein, we report dried blood spot (DBS) sampling, in combination with diamino-4,5-methylenedioxybenzene derivatization, for profiling sialic acids in blood samples with minimal alteration in O-acetylation patterns. The feasibility of the method was first evaluated by analyzing sialic acids in crucian carp blood and comparing with traditional blood/plasma sample preparation procedures. A total of 19 different sialic acids were identified by using liquid chromatography–Orbitrap mass spectrometry, including four mono-O-acetylated N-acetylneuraminic acids, four mono-O-acetylated N-glycolylneuraminic acids, six di-O-acetylated N-acetylneuraminic acids, and three tri-O-acetylated N-acetylneuraminic acids. The long-term storage study indicated that DBS sampling could effectively preserve the O-acetylation information for at least 6 weeks. Thus, it is demonstrated that this method is a valuable tool for the study of sialic acid diversity, especially for the characterization of isomeric structures.