Isolation and quantitative determination of inulin-type oligosaccharides in roots of Morinda officinalis

Inulin-type oligosaccharides with different degree of polymerization (DP) were isolated from the traditional Chinese medicine: Morina officinalis by size-exclusion chromatography, and their purities were determined by HPLC–ELSD equipped with cyclodextrin-bond column. Through analysis, the purities of obtained inulin-type oligosaccharides were higher more than 98% by one-step process. The structures of inulin-type oligosaccharides were confirmed by a combination of NMR, MS as well as comparison with already existing NMR data. Using d-fructose and the isolated inulin-type oligosaccharides as standards, a determination method of monosaccharide and inulin-type oligosaccharides in Morinda officinalis was first developed and validated. The validated method was successfully applied to analyze monosaccharide and oligosaccharides in three types of roots of M. officinalis and provided a new basis of assessment on quality of M. officinalis.