Development of Bioactive Functions in Hydrangeae Dulcis Folium. V. On the Antiallergic and Antimicrobial Principles of Hydrangeae Dulcis Folium. (2). Thunberginols C, D, and E, Thunberginol G 3'-O-Glucoside, (-)-Hydrangenol 4'-O-Glucoside, and (+)-Hydrangenol 4'-O-Glucoside

Following the characterization of thunberginols A, B, and F, six bioactive principles, thunberginols C, D, and E, thunberginol G 3'-O-glucoside, (-)-hydrangenol 4'-O-glucoside, and (+)-hydrangenol 4'-O-glucoside, were isolated from Hydrangeae Dulcis Folium, the processed leaves of Hydrangea macrophylla SERINGE var. thunbergii MAKINO, together with four kaempferol and quercetin oligoglycosides. Their chemical structures have been determined on the basis of chemical and physicochemical evidence. Thunberginols C, D, E, and G and (-)-hydrangenol 4'-O-glucoside showed antiallergic activity in the in vitro bioassay using the Schultz-Dale reaction. These components also exhibited inhibitory activities on the histamine release from rat mast cells and on the histamine-induced contraction in isolated guinea pig tracheal chain. In addition, thunberginols C, D, E, and G showed antimicrobial activities against oral bacteria.