Isolation and Structural Characterization of a New Minor Diterpene Glycoside from Stevia rebaudiana

From the commercial extract of the leaves of the sweet plant Stevia rebaudiana Bertoni obtained from Sinochem Qingdao Co. Ltd., a new diterpene glycoside having three β-D-glucopyranosyl units of which two of them were connected in a relatively rare linkage of 3-β-D-glucobiosyl substitution at C-19 position of the aglycone steviol. The structure of the new compound has been characterized as 13-β-D-glucopyranosyloxy ent-kaur-16-en-19-oic acid-[(3-O-β-D- glucopyranosyl-β-D-glucopyranosyl) ester (1) on the basis of extensive 1D (1H and 13C) and 2D NMR (TOCSY, HMQC, and HMBC), and High Resolution mass spectroscopic data as well as hydrolysis studies.