NMR Spectral Assignments and Hydrolysis Studies of Dulcosides A and B

The complete 1H and 13C NMR assignments for the two diterpene glycosides 13-[(2-O-a-L-rhamnopyranosyl-B-D-glucopyranosyl)oxy]-ent-kaur-16-en-19-oic acid B-D-glucopyranosyl ester (Dulcoside A) and 13-[(2-O-a-L-rhamnopyranosyl-3-O-B-D-glucopyranosyl-B-D-glucopyranosyl)oxy]-ent-kaur-16-en-19-oic acid B-D-glucopyranosyl ester (Dulcoside B) isolated from Stevia rebaudiana were achieved by the extensive NMR (1H and 13C, COSY, HSQC, HMBC) and mass spectral data. Further, hydrolysis of the two compounds Dulcosides A and B was performed using acid and enzymatic studies to identify their aglycone and sugar residues.