The role of sialic acids in the development of cognitive functions has drawn the attention of neuroscientists in recent years . The distribution of sialic acids in brain tissue and its relation to certain pathologies has been extensively studied . Sialic acids are an important component of gangliosides present in brain tissue and in the nervous system. In order to quantify the level of total sialic acids in brain, these have to be released from their parent glycolipid or glycoprotein to be measured.
The objective of this work was to adapt an existing method [2-3] for the quantification of the two most common sialic acids, N-acetylneuraminic acid (Neu5Ac) and N-glycolylneuraminic acid (Neu5Gc), to the analysis of those components in brain tissue. Sialic acids were released from their parent ganglioside by acid hydrolysis, and subsequentially derivatized by quinoxaline formation. The resulting quinoxaline derivatives were quantified by UHPLC-FLD (Figure 1). The method was validated on a brain tissue homogenate containing around 130 mg 100g-1 of sialic acids. The recovery was estimated to be 90%. We successfully optimized the homogenization and hydrolysis of brain tissues for the release of sialic acids. Furthermore, we optimized the derivatization of released sialic acids by using a more stable quinoxaline , minimizing the use of toxic stabilizers in the reaction.
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