Neuraminidase-resistant hemagglutination inhibitors: acrylamide copolymers containing a C-glycoside of N-acetylneuraminic acid

Copolymers consisting of a polyacrylamide backbone with side chains terminated in C-glycosidic analogs of N-acetylneuraminic acid were synthesized by free radical copolymerization of alpha-2-C-[3-[[2-(N-acryloylamino)ethyl]thio]propyl]-N- acetylneuraminic acid (5) with acrylamide. Unlike natural and synthetic polyvalent materials that contain N-acetylneuraminic acid in O-glycosidic form, these C-glycosidic copolymers resist neuraminidase-catalyzed cleavage of the neuraminic acid residue from the copolymer backbone. Examination of these C-glycosidic copolymers in a hemagglutination inhibition assay indicated that they are as effective in vitro as polyvalent O-glycosidic copolymers in inhibiting agglutination of erythrocytes by influenza virus. The minimum value of the inhibition constant, calculated on the basis of the concentration of Neu5Ac groups in solution, is Ki(HAI) approximately 10(-7) M for both copolymers. The inhibitory potency of the C-glycoside-based copolymers becomes more significant at lower concentrations of Neu5Ac moieties in solution than does the inhibitory potency of the O-glycoside-based copolymer.