Structure of Tanacetan, a Pectic Polysaccharide from Tansy Tanacetum vulgare L.

Abstract

Tanacetan TVF was found to have a branched structure with a backbone of linear α-1,4-D-galacturonan. The ramified regions consist of linear α-1,2-L-rhamno-α-1,4-D-galacturonan as the core. The side chains appear to attach to the 4-position of the L-rhamnopyranose residues. They are present as single β-galactopyranose residues or a branching β-1,4-galactopyranan bearing 4,6-substituted β-D-galactopyranose residues as branched points. In addition, the ramified regions contain side chains of a branched α-1,5-arabinofuranan possessing 2,5- and 3,5-substituted α-L-arabinofuranose residues as branching points. Some side chains of rhamnogalacturonan appear to be arabinogalactan which contains branched sugar chains of α-1,5-arabinofuranan attached to the linear chains of β-1,4-galactopyranan by 1,3- and 1,6-linkages. The residues of α-L-arabinofuranose seem to occupy the terminal positions of the arabinogalactan side chains.