Characterization of polysaccharides from a new variety of Stevia rebaudiana

Stevia rebaudiana (Bert.) is a plant known worldwide for containing steviol glycosides in its leaves, high-intensity sweetener. The Stevia UEM-13 variety was developed in Brazil and is considered an elite variety for containing high levels of rebaudiodiside A, the sweetener with the best sensory profile in Stevia. However, it is necessary to investigate other metabolites of this variety, such as polysaccharides, which have shown functional and antiviral activities. In this sense, the objective of this work was to obtain and investigate the chemical structure of polysaccharides from the Stevia variety UEM-13. An aqueous extraction was performed from the dried and ground leaves and precipitation with ethanol. The precipitate was subjected to dialysis, a high-intensity and subsequently to a DEAE-cellulose column. The contents of total carbohydrates, proteins, phenolic compounds, and uronic acids were determined during all steps. A fraction (F2) was obtained containing 50% carbohydrates with heterogeneous profile by HPSEC. The monosaccharide composition performed by GC-MS identified 35.7% arabinose and 16.5% galactose and by NMR it was possible to suggest that the polysaccharide is a type II arabinogalactan (AG-II). AG-II was also found in other varieties of Stevia and has shown functional properties, which may contribute to disease prevention and health promotion.