Spondias purpurea Exudate polysaccharide as affinity matrix for the isolation of a galactose-binding-lectin

Spondias purpurea L., popularly known as ciriguela, is native and widespread tree from Mexico through Northern Peru and Brazil, particularly in semi-arid zones. This tree exudes a water soluble polysaccharide, constituted of a (1→3) linked galactan backbone substituted at C6 with d-galactose, d-xylose, l-arabinose, l-rhamnose and glucuronic acid units. Brazilian polysaccharide differs from Venezuelan on the amount of acid and arabinose as well as the presence of fucose and glucose as minor sugar. The d-galactose substitution (1→6) confers to the polysaccharide the peculiar capacity of binding -d-galactose specific lectins after cross-linking with epichlorohydrin. The gel obtained was able to specifically retain d-galactose-binding-lectins, among with those from Artocarpus incisa, Artocarpus integrifolia, Erythrina velutina and Ricinus communis. On the other hand, no glucose-binding-lectins were retained.