Absolute stereostructures of hydramacrosides A and B, new bioactive secoiridoid glucoside complexes from the leaves of Hydrangea macrophylla Seringe var. thunbergii Makino.

Two new bioactive secoiridoid glucoside complexes named 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 inhibitory effect on the histamine release from rat mast cells induced by antigen-antibody reaction.