Neuraminic acid biological activity

Neuraminic acid and its Structures, Chemistry, Biological Activity ARMANDODORIANO BIANCO AND CRISTIANA MELCHIONI 103... 

NEURAMINIC ACID - STRUCTURE, CHEMISTRY, BIOLOGICAL ACTIVITY... 

Sialic acid was the first virus receptor identified. Hirst and McClelland and Hare discovered that influenza virus is able to hemagglutinate and that adsorbed virus is eluted from erythrocytes on incubation at 37°C, indicating an enzymatic destruction of a receptor substance on the cells [1, 2]. When a similar enzymatic activity was subsequently detected in Vibrio cholerae cultures, the term receptor-destroying enzyme was introduced [3]. The substance released by the viral enzyme from soluble hemagglutination inhibitors was initially characterized as a carbohydrate of low molecular weight [4] and then identified in crystalline form as A-acetyl-o-neuraminic acid [5]. Thus, it was clear that the receptor determinant of influenza virus was sialic acid and that the viral enzyme was a neuraminidase. Furthermore, for the first time an important biological function of sialic acid had been identified. 

Stereo pictures of the different bioactive conformations of sLe from Table 1 are shown in Figure 7. It has been shown that for biological activity the relative orientation of the fucose and the neuraminic acid residue are relevant [11, 12]. Following this guide line, a potent mimic of sLe had been synthesized [11-13]. A conformational analysis of this sLe mimic in the free and bound state [60] clearly showed that the bioactive conformation is very similar to the one derived originally for sLe bound to E-selectin [19]. 

Pepper (1968) investigated the role of sialic acid in horse serum on the inhibition of hemagglutination by Asian influenza virus. Horse serum has N-acetyl, N-glycoyl, and the 4-0-acetylated derivatives of neuraminic acid (cf. Chapter 1). The biological activity of horse serum specifically toward the Az strain of influenza virus appears to be determined by the N,0-diacetylneuraminic acid component in c -ma-croglobulin. 

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