Three New Triterpene Glycosides from the Roots of Deutzia x Hybrida "Strawberry Fields" (Hydrangeaceae)

Three new triterpene glycosides were isolated from Deutzia x hybrida "Strawberry Fields" cultivar via aqueous-ethanolic extraction of the roots, including one derivative of sumaresinolic acid and two of echinocystic acid: 3-O-β-D-glucuronopyranosylsumaresinolic acid 28-O-β-D-xylopyranosyl-(1→4)-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranosyl ester, 3-O-β-D-glucuronopyranosylechinocystic acid 28-O-β-D-xylopyranosyl-(1→4)-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranosyl ester, and 3-O-α-L-arabinopyranosyl-(1→3)-β-D-glucuronopyranosylechinocystic acid 28-O-β-D-xylopyranosyl-(1→4)-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranosyl ester. As none of the isolated saponins were previously documented in the literature, their structural elucidation required extensive 1D and homo- and heteronuclear 2D NMR spectroscopy, as well as mass spectrometry analysis. All three glycosides were tested for their stimulatory activity of the sweet taste receptor TAS1R2/TAS1R3. It is the first chemical and biological investigation of Deutzia x hybrida "Strawberry Fields" as well as the first report of sumaresinolic acid glycosides in Deutzia genus.