Undescribed Triterpenes from the Leaves of Syzygium myrsinifolium with Their α‐Glucosidase and α‐Amylase Inhibition Activity

Abstract Two undescribed triterpenes, syzyfolium A ( 1 ) and syzyfolium B ( 2 ), together with twelve known compounds, terminolic acid ( 3 ), actinidic acid ( 4 ), piscidinol A ( 5 ), threo ‐dihydroxydehydrodiconiferyl alcohol ( 6 ), lariciresinol‐4‐ O ‐ β ‐D‐glucoside ( 7 ), icariol A 2 ( 8 ), 14 β ,15 β ‐dihydroxyklaineanone ( 9 ), garcimangosone D ( 10 ), (+)‐catechin ( 11 ), myricetin‐3‐ O ‐ α ‐L‐rhamnopyranoside ( 12 ), quercitrin ( 13 ), and 3, 4, 5‐trimethoxyphenyl‐(6′‐ O ‐galloyl)‐ O ‐ β ‐D‐glucopyranoside ( 14 ) were isolated from the leaves of Syzygium myrsinifolium . Their chemical structures were determined by IR, HR‐ESI‐MS, 1D and 2D NMR spectra. Compounds 3 and 4 inhibited significantly α ‐glucosidase with IC 50 values of 23.99 and 36.84, respectively, and compounds 1 and 2 inhibited significantly α ‐amylase with IC 50 values of 35.48 and 43.65 μM, respectively.