PREPARATION OF SPACER-CONTAINING DI-SACCHARIDE, TRI-SACCHARIDE, AND TETRASACCHARIDE FRAGMENTS OF THE CIRCULATING ANODIC ANTIGEN OF SCHISTOSOMA-MANSONI FOR DIAGNOSTIC PURPOSES

The chemical synthesis of beta-D-GlcpA-(1 --> 3)-beta-D-GalpNAc-(1 --> O)CH2CH = CH2, beta-D-GalpNAc-(1 --> 6)-[beta-D-GlcpA-(1 --> 3)]-beta -D-GalpNAc-(1 --> O)CH2CH = CH2, and beta-D-GlcpA-(1 --> 3)-beta-D-Gal pNAc-(1 --> 6)-[beta-D-GlcpA-(1 --> 3)]-beta-D-GalpNAc-(1 --> O)CH2CH = CH2 is described. These oligosaccharides represent fragments of the circulating anodic antigen, secreted by the parasite Schistosoma manso ni in the circulatory system of the host. The applied synthesis strate gy includes the preparation of a non-oxidised backbone oligosaccharide , with a levulinoyl group at O-6 of the beta-D-glucose residue. After the selective removal of the levulinoyl group, the obtained hydroxyl f unctions were converted into carboxyl groups, using pyridinium dichrom ate and acetic anhydride in dichloromethane, to afford the desired glu curonic-acid-containing oligosaccharides. Subsequently, the allyl glyc osides have been elongated with cysteamine to give the corresponding a minespacer-containing oligosaccharides. (C) 1998 Elsevier Science Ltd. All rights reserved.