A new oleanane-type triterpenoid saponin with α-glucosidase inhibitory activity from Camellia nitidissima

A new oleanane-type triterpenoid saponin, 21β, 22α-di-O-angeloyl-15α, 16α, 28-trihydroxyolean-12-ene 3β-O-α-L-rhamnopyranosyl-(1→3)-α-D-xylopyranosyl-(1→3)-β-D-glucopyranoside (1), together with five known compounds (2-5), were isolated from Camellia nitidissima. Their structures were elucidated based on spectroscopic methods, including extensive NMR and MS spectra. Compound 1 showed potential inhibitory activity on α-glucosidase with the IC₅₀ values of 185.9 ± 44.5 µmol/L.