Separation and characterization of dextran extracted from deteriorated sugarcane

In this research work, dextran was extracted from deteriorated sugarcane by alcohol precipitation and purified by gel filtration chromatography. Total acid hydrolysis and enzymatic degradation were utilized to confirm the purity of separated polysaccharide. Using the more recently available techniques such as (H-1,C-13) and two-dimensional (COSY and HMQC) NMR spectral analysis, methylation GC-MS and MALDI-TOF mass spectrometry, the structure of sugarcane dextran (SC-Dex) was investigated. On the basis of all spectra, SC-Dex showed a branched polysaccharide that contained only D-glucose residues in consecutive alpha-(1-6) linkages in the main chain with alpha-(1-3) branches. Methylation analysis showed that, the degree of alpha-(1-3) branching levels was 4.37%. Several structural fragments were identified from MALDI-TOF spectrum with peak-to-peak mass difference of 162 g mol(-1), which confirmed that the repeat unit in SC-Dex was D-glucose. The surface morphology of SC-D ex, revealed the spherically shaped and porous structure. Using HPSEC-MALLS-RI system, the average molecular weight of SC-Dex was estimated to be 1.753 x 10(6) g mol(-1) with an index of polydispersity value of 1.069. (C) 2013 Elsevier B.V. All rights reserved.