Specific distribution of sialic acids in animal tissues as examined by LC - ESI-MS after derivatization with 1,2-diamino-4,5-methylenedioxybenzene

Simultaneous analysis of sialic acids has been a challenging target, becaus e sialic acids having N- or O-acetyl, glycolyl, and sulfonic acid ester gro ups are labile during their release from carbohydrate chains and analytical procedures. In the present paper, we propose a method using high-performan ce liquid chromatography coupled with eletrospray ionization mass spectrome try (HPLC-ESI-MS). The method was evaluated by applying to the analysis of sialic acids in various tissues, especially digestive organs in mice and ra ts. The method was based on the in situ precolumn derivatization of sialic acids after releasing them by hydrolysis. The sialic acids were derivatized with 1,2-diamino-4,5-methylenedioxybenzene to form highly fluorescent quin oxaline derivatives. By using two different hydrolysis conditions (i.e., wi th 2 M acetic acid and with 0. 1 M hydrochloric acid), both total sialic ac ids and sialic acid distributions were easily determined. We found that sia lic acids showed characteristic distributions in the tissues of mice and ra ts. Further, HPLC-ESI-MS revealed that all the tissues examined in mice and rats commonly contained highly acetylated sialic acids and 8-O-sulfated N- acetylneuraminic acid.