A further amendment to the classical core structure of gum arabic (Acacia senegal)

Using the more recently available techniques such as methylation–GC–MS, 1D (1H, 13C) and 2D (COSY, TOCSY, HMQC and HMBC) NMR spectral analysis, we have revisited the classical structure of gum arabic (Acacia senegal). Methylation and GC–MS analysis confirmed that gum arabic (A. senegal) is a highly branched polysaccharide with the backbone composed of 1,3-linked galactopyransyl (Galp) residues substituted at O-2, O-6 or O-4 positions. The terminal sugar residues are 59.5% of the total sugars. The residues of →2,3,6-β-d-Galp1→, →3,4-Galp1→, →3,4,6-Galp1→ and substitutions at O-2 and O-4 position were not identified in previous studies.

Proposed structure of gum arabic (Acacia senegal). A schematic structure is proposed as follows (with the newly identified residues identified in red).Figure optionsDownload as PowerPoint slide