The chemical structure of galactomannan isolated from seeds of Delonix regia

Abstract

A galactomannan isolated from seeds of Delonix regia was investigated. The specific rotation of the galactomannan was +15° at 25 °C. The molecular mass of the galactomannnan was estimated to be 2.5 × 105. The ratio of D-mannose to D-galactose was estimated approximately to be 4.0:1.0 by HPLC and 1H-NMR. NMR (1H and 13C) spectra, and methylation analysis of the galactomannan indicated that it was composed of 1,4-linked β-D-mannose, 1,4,6-linked β-D-mannose, and terminal α-D-galactose. It was composed of pentasaccharide repeating-units, the chemical structure of which is proposed below.