ISOLATION AND STRUCTURE ELUCIDATION OF MONOACYL-IRIDOID AND DIACYL-IRIDOID DIGLYCOSIDES FROM LEAVES OF PREMNA-JAPONICA

On further phytochemical investigation of Premna japonica, four new mono and diacyl 6-alpha-L-rhamnopyranosylcatalpols were isolated. Their structures were established to be 6-O-alpha-L-(2''-O-p-methoxycinnamoyl)rhamnopyranosylcatalpol {1} and 6-O-alpha-L-(3''-O-p-methoxycinnamoyl)rhamnopyranosylcatalpol {3} and 6-O-alpha-L-(2''-O-p-methoxycinnamoyl-4''-O-acetyl)rhamnopyranosylcatalpol {5} and 6-O-alpha-L-(3''-O-p-methoxycinnamoyl-4''-O-acetyl)rhamnopyranosylcatalpol {6} from spectroscopic data and the results of acetylation experiments.