New C20-gibberellin diterpene from the leaves of Schefflera sessiliflora De P. V.
From the leaves of Schefflera sessiliflora De P. V., one new C20-gibberellin diterpene 2β,12β-dihydroxygibberellin (12β-hydroxy-GA110 or 2β-hydroxy-GA112) (1), together with three known compounds, trans-tiliroside (2), kaempferol 3-O-β-d-glucuronopyranoside (3), 5-p-trans-coumaroylquinic acid (4), was isolated for the first time from the genus Schefflera by various chromatography methods. Their structures were elucidated by IR, UV, HR-ESI-MS, NMR 1D and 2D experiments and comparison with previous reported data. The α-glucosidase inhibitory activity of all compounds was measured. The isolates (2, 3) showed better α-glucosidase inhibitory activity (IC50 = 134.60, 147.10 μM, respectively) than the standard drug acarbose (IC50 = 214.50 μM).