GUM HETEROPOLYSACCHARIDE AND FREE REDUCING MONOSACCHARIDES AND OLIGOSACCHARIDES OF ANADENANTHERA-COLUBRINA

The gum from Anadenanthera colubrina consists mainly of a complex high -arabinose heteropolysaccharide with a (1-->3)-linked beta-D-Galp main -chain and many different side-chains. These contain beta-D-Galp-[(1-- >6)-beta-D-Galp](m)-(1-->6)-, substituted in turn at O-3 by alpha-L-Ar af-[(1-->3)-alpha-L-Araf-](0.2). Also present are (1) main-chain units substituted at O-4 and O-6 by alpha-L-Araf units, (2) side-chains of hap-(1-->4)-beta-D-GlcpA-(1-->6)-beta-Galp-groups, (3) alpha-L-Arap no n-reducing end-units linked (1-->6) to D-Galp, and (4) beta-Araf and b eta-Arap structures. For the first time, a plant gum exudate was found to contain in the natural state, reducing low M-r carbohydrates. Thes e were rhamnose (0.6%), arabinose (4.7%), mannose (0.1%), galactose (0 .8%) and many oligosaccharides (0.6%; 11 with different R(F)s with the majority containing arabinose). They were all mixtures with the excep tion of alpha-Rhap-(1-->4)-beta-D-GlcpA-(1-->6)-alpha beta-Gal and an incompletely identified hexasaccharide, probably having alpha-L-Araf-( 1-->4)-beta-D-Galp- and -alpha-L-Araf-(1-->3)-beta-D-Galp-structures. The mono- and oligosaccharides do not appear to arise via in situ auto hydrolysis of the gum. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.