NMR, Mass and DFT Studies of Ariose: A Novel Oligosaccharide from Donkey (Equus asinus) Milk

Abstract

Oligosaccharides play a key role in various physiological, pathological and biological activities such as biological recognition, anti-complementary, anti-coagulant, anti-inflammatory, anti-viral, anti-bacterial, anti-tumour, anti-oxidant, lipid lowering, immunological activities, prebiotic activity and hypoglycemic activity. In our endeavour to find biologically active novel oligosaccharides, donkey milk was taken, which is a rich source of oligosaccahrides and its milk is used as anti-hypertensive, anti-oxidant and heart strengthening agent in folk medicine. For this purpose donkey milk was processed by modified method of Kobata and Ginsburg followed by Gel filtration HPLC and Column Chromatography (CC) which resulted in the isolation of one novel milk oligosaccharide namely Ariose. The structure of purified milk oligosaccharide was determined with the help of chemical degradation, chemical transformation, spectroscopic techniques like 1D-NMR (¹H and ¹³C), 2D-NMR (COSY, TOCSY, HSQC and HMBC), Structure Reporter Group (SRG) theory and Mass spectrometry (ESI-MS). The geometry optimization of compound was done by using B3LYP method at 6-31G (d, p) basis set employing Density Functional Theory (DFT).