Five New Oleanane Triterpene Saponins from Camellia petelotii and Their Alpha-glucosidase Inhibitory Activity

Abstract

Five new triterpenoid glycosides, named campetelosides A-E (1-5), together with three known compounds, chikusetsusaponin IVa (6), umbellatoside B (7), and silvioside E (8) were isolated from the leaves of Camellia petelotii (Merr.) Sealy. Their chemical structures were determined by interpretations of HR-ESI-MS and NMR spectra. In addition, compounds 1-8 were evaluated for their α-glucosidase inhibitory effects. Compounds 1-3 significantly showed α-glucosidase inhibitory activity with IC₅₀ values of 166.7±6.0, 45.9±2.6, and 395.3±10.5 μM, respectively, compared to that of the positive control, acarbose, with an IC₅₀ value of 200.4±10.5 μM.

Keywords: Camellia petelotii; Theaceae; oleanane triterpene; α-glucosidase inhibitory.