Extraction, purification and structural characterization of a galactoglucomannan from the gabiroba fruit (Campomanesia xanthocarpa Berg), Myrtaceae family

•A galactoglucomannan (GGM) was purified from pulp of C. xanthocarpa..•The GGM main chain comprises β-d-Glcp and β-d-Manp units (1→4)-linked.•α-d-Galp units substitutions occur mainly at the O-6 position of β-d-Manp units.•The chemical structure of a GGM is reported for the first time in Myrtaceae family. In this study, we isolated and structurally characterized, for the first time, a galactoglucomannan (GGM) from the pulp of gabiroba, a Myrtaceae family species. The HPSEC-MALLS-RI analysis showed a homogeneous polysaccharide with molar mass of 25,340gmol−1. The monosaccharide composition showed that the GGM consisted of Man:Glc:Gal in a molar ratio of 1:1:0.6. Methylation and 1D and 2D NMR analyses suggested that the main chain of the GGM consisted of β-d-Glcp and β-d-Manp units (1→4)-linked. The α-d-Galp substitutions occur mainly at O-6 position of β-d-Manp units. The glycosidic linkages of the GGM were evident by the presence of the characteristic signals of 4-O-substituted residues at δ 78.6/3.69 for both β-d-Glcp and β-d-Manp. Furthermore, the O-6 substitutions for both β-d-Glcp and β-d-Manp units were confirmed by signals at δ 67.1/4.00 and 3.93. The interglycosidic correlations, obtained through the analysis of the HMBC spectrum, further confirm the structure.