Sialic acid (SA) is a naturally occurring monosaccharide found in glycoproteins and glycolipids. Changes in the expression of SA are associated with several diseases; thus, the detection of SA is of great significance for biological research, cancer diagnosis, and treatment. Boronic acid analogs have emerged as a promis- ing tool for detecting sugars such as SA due to its reversible covalent bonding ability. In this study, 11 bis- boronic acid compounds and 2 mono-boronic acid compounds were synthesized via a highly efficient Ugi-4CR strategy. The synthesized compounds were subjected to affinity fluorescence binding experi- ments to evaluate their binding capability to SA. Compound A1 was shown to have a promising binding constant of 2602 ± 100 M−1 at pH = 6.0. Density Functional Theory (DFT) calculations examining the binding modes between A1 and SA indicated that the position of the boronic acid functional group was strongly correlated with its interaction with SA’s α-hydroxy acid unit.
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Organic and Biomolecular Chemistry 22, p.1639-1645
