Comparative study of the gum exudates from two Citrus spp. (Rutaceae) located in Venezuela (Citrus spp. gum exudates)

The Rutaceae family is represented in Venezuela by 26 genera and 84 species. Few studies have been published about Rutaceae gums. Citrus aurantiifolia Swing. and Citrus paradisi MacFayden (Rutaceae) exudate, a clear, highly water-soluble gums. The characterization of their gum exudates was done by classical analytical methods and Carbon-13 NMR spectroscopy. C. aurantiifolia gum has the most complex structure, containing galactose, arabinose, xylose, rhamnose and uronic acids. This sugar composition differs from that of the C. paradisi gum, which contains only galactose, arabinose and uronic acids. C. paradisi Carbon-13 NMR spectrum confirmed the absence of xylose and rhamnose and in contrast to C. aurantiifolia gum, showed no evidence of a-L-arabinofuranose residues in its structure. Both gums are predominantly polysaccharides but they also contain amino acids and fatty acids. Chemical and spectroscopic studies showed important similarities and differences in the structural features of the C. aurantiifolia and C. paradisi gums.