A new lupane glycoside isolated from <i>Dendrobium officinale</i> with <i>α</i>‐glucosidase inhibitory activity

Abstract A new lupane triterpene glycoside ( 1 ) and four known compounds ( 2 ‐ 5 ) were isolated from the aerial parts of Dendrobium officinale . Their chemical structures were determined to be 3‐ O ‐ α ‐L‐arabinopyranosylbetulinic acid 28‐ O ‐ β ‐D‐glucopyranosyl‐(1→6)‐ β ‐D‐glucopyranosyl ester ( 1 ), 3‐ O ‐ α ‐L‐arabinopyranosylbetulinic acid 28‐ O ‐ α ‐L‐rhamnopyranosyl‐(1→4)‐ β ‐D‐glucopyranosyl‐(1→6)‐ β ‐ D‐glucopyranosyl ester ( 2 ), 3‐ O ‐ β ‐D‐glucopyranosylbetulinic acid 28‐ O ‐ α ‐L‐rhamnopyranosyl‐(1→4)‐ β ‐D‐glucopyranosyl‐(1→6)‐ β ‐D‐glucopyranosyl ester ( 3 ), 6α‐hydroxylup‐20(29)‐en‐3‐on 28‐oic acid ( 4 ), and lupeol ( 5 ) by analyzing the HR‐ESI‐MS, 1D and 2D NMR spectra including COSY and NOESY. Compounds 1 , 2 and 4 showed weak α‐glucosidase inhibitory activity with IC 50 values ranging from 87.5 to 98.2 µM.