Chemical Constituents from the Leaves of Hydrangea macrophylla var. thunbergii(III) : Absolute Stereostructures of Hydramacrosides A and B, Secoiridoid Glucoside Complexes with Inhibitory Activity on Histamine Release

Abstract

Following the characterization of dihydroisocoumarin constituents, two secoiridoid glucoside complexes, called hydramacrosides A and B, were isolated from the leaves of Hydrangea macrophylla SERINGE var. thunbergii MAKINO. The absolute stereostructures of hydramacrosides A and B were elucidated on the basis of chemical and physicochemical evidence, which included the application of the ¹³C-NMR glycosylation shift rule of 1, 1'-disaccharides and the modified Mosher's method. Hydramacrosides A and B exhibited an inhibitory effect on histamine release from rat mast cells induced by an antigen-antibody reaction.