Application of ¹³C Nuclear Magnetic Resonance Spectroscopy to Chemistry of Glycosides : Structures of Paniculosides-I, -II, -III, -IV, and -V, Diterpene Glucosides of Stevia paniculata LAG.

Abstract

From the aerial part of Stevia paniculata (Compositae), five new diterpene glucosides, named paniculosides I-V (5-9) were isolated. On comparison of ¹³C nuclear magnetic resonance spectra of these glucosides with those of the aglycones, ent-15α-hydroxykaur-16-en-19-oic acid (1) [as methyl ester (17)], ent-11α-hydroxy-15-oxokaur-16-en-19-oic acid (2), ent-11α, 15α-dihydroxykaur-16-en-19-oic acid (3), and ent-16β, 17-dihydroxykauran-19-oic acid (4) as well as some model glucosides, paniculosides I-IV (5-8) can be formulated as β-glucopyranosyl ester of 1, 3, 2, and 4, respectively and paniculoside-V (9) can be represented by 15-O-β-glucopyranoside of 5.