Studies on the constituents of Syringa species. XII. New glycosides from the leaves of Syringa reticulata (BLUME) HARA

Three new glycosides, 6'-O-alpha-D-galactopyranosylsyringopicroside (1), secologanoside 7-methyl ester (2) and (+)-lariciresinol 4'-O-beta-D-glucopyranosyl-(1-->3)-beta-D-glucopyranoside (3), were isolated from the leaves of Syringa reticulata. Their structures were established on the basis of chemical and spectral data. Compound 1 is the first naturally occurring iridoid di-glycoside having melibiose. Comparison of the spectral data of 2 and that previously recognized as secologanoside 7-methyl ester led to the conclusion that the recognized structure should be revised to the sodium salt of secoxyloganin (2').