Degradation of cellooligosaccharides in oxidative medium and alkaline medium: HPLC, FTIR, and GC-MS analyses

The chemical degradations of highly-purified cellotriose, cellotetraose, and cellopentaose in H2O2 and NaOH media were studied, respectively. The degradation products were analyzed by HPLC, FTIR, and GC-MS techniques. The results show that for the three oligosaccharides the main oxidative degradation products are 2, 3-dihydroxy-butanedioic acid, 2-keto-gluconic acid, glucopyranose, D-glucose, D-gluconic acid, and cellooligosaccharides with lower DP. A small amount of arabinose is formed during the oxidation of cellotriose. The main alkaline degradation products for the three oligomers include 3-deoxy-isosaccharinic acid-1,4-lactone and 3-deoxy-hexonic acid-1,4-lactone. Arabinose coumpounds are found to be an accidental degradation product of cellotriose. Finally, the possible formation mechanisms are proposed, including 2,3-dihydroxy-butanedioic acid, 2-keto-gluconic acid, D-gluconic acid, arabinose, 3-deoxy-isosaccharinic acid-1,4-lactone, and 3-deoxy-hexonic acid-1,4-lactone. The radical attack from H2O2 is probably at the glycosidic linkage, resulting in the formation of a series of degradation products. Degradations of cellooligosaccharides in alkaline solution are elucidated to follow an enediol anion reaction mechanism.