THE MOLECULAR CHARACTERIZATION OF THE POLYSACCHARIDE GUM FROM LANGUCULARIA-RACEMOSA

A polysaccharide isolated from the exudate of Laguncularia racemosa, ( Combretaceae) has been investigated using Smith-degradation, methylati on analysis, hydrolysis, and C-13-NMR spectroscopy. The backbone of th e structure is constituted of uronic acids, galactose and rhamnose. A complex pentasaccharide, constituted of these sugars, was isolated fro m the original gum and degradation products. This oligosaccharide is, probably, the main structural feature of the investigated polysacchari de. On the other hand, according to chemical and spectral evidence rha mnose is present, predominantly as internal residues. Arabinosyl (pyra nosyl and furanosyl) residues and some galactosyl, glucuronic acid and 4-O-methyl-alpha-D-glucuronic acid residues are located in branches. (C) 1998 Elsevier Science Ltd. All rights reserved.