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

Abstract

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- D-mannose residues, with differing proportions of side chains consisting of single α- D-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.