Additional minor diterpene glycosides from Stevia rebaudiana Bertoni

Two additional novel minor diterpene glycosides were isolated from the commercial extract of the leaves of Stevia rebaudiana Bertoni. The structures of the new compounds were identified as 13-{β-D-glucopyranosyl-(1 → 2)-O-[β-D-glucopyranosyl-(1 → 3)-β-D-glucopyranosyl-oxy} ent-kaur-16-en-19-oic acid {β-D-xylopyranosyl-(1 → 2)-O-[β-D-glucopyranosyl-(1 → 3)]-O-β-D-glucupyranosyl-ester} (1), and 13-{β-D-6-deoxy-glucopyranosyl-(1 → 2)-O-[β-D-glucopyranosyl-(1 → 3)-β-D-glucopyranosyl-oxy} ent-kaur-16-en-19-oic acid {β-D-glucopyranosyl-(1 → 2)-O-[β-D-glucopyranosyl-(1 → 3)-β-D-gluco-pyranosyl-ester} (2), on the basis of extensive 1D (1H- and 13C-) 2D NMR (COSY, HSQC and HMBC) and MS spectroscopic data as well as chemical studies.