Structures of the galactomannans from seeds of Annona muricata, Arenga saccharifera, Cocos nucifera, Convolvulus tricolor, and Sophora japonica

Galactomannans were isolated from ripe seeds of Annona muricata (Annonaceae), Convolvulus tricolor (Convolvulaceae), Sophora japonica (Leguminosae), and from immature seeds of Arenga saccharifera and Cocos nucifera (both Palmae). Their sugar compositions were determined and their structures studied by the methylation and periodate-oxidation techniques. All the galactomannans studied are of the leguminous type, the molecules having main chains consisting of (1→4)-linked β- -mannose residues, with differing proportions of side chains consisting of single - -galactose residues linked to the main chains by (1→6)-bonds. The molecular weights were found to vary from 6,000 (Sophora) to 17,000 (Arenga). The isolation of the galactomannan of Annona is the first recorded occurrence of this type of polysaccharide in the family Annonaceae, whereas there has been a previous report of the occurrence of a galactomannan in the Convolvulaceae; the study of the structure of the Sophora galactomannan is the first one in the tribe Sophoreae of the Leguminosae.