Acylated iridoid diglycosides from the cultivated endangered ornamental tree Gmelina hainanensis

Abstract Two new ( 1 and 2 ) and 10 known ( 3 − 12 ) acylated iridoid diglycosides were isolated from the twigs and leaves of the cultivated endangered ornamental plant Gmelina hainanensis . Based on spectroscopic data interpretation and chemical transformation, the new triacyl and the new diacyl iridoid diglycosides were established to be 6- O - α- L-(2″,3″-di- O -acetyl-4″- O - cis -cinnamoyl)rhamnopyranosylcatalpol ( 1 ) and 6- O -α- l -(2″,4″-di- O - trans -cinnamoyl)rhamnopyranosylcatalpol ( 2 ), respectively. All the isolates were evaluated for their inhibitory effects against the protein tyrosine phosphatase 1 B (PTP1B) enzyme.