SummaryFrom Hydrangea macrophylla var. macrophylla, four new secoiridoid glucosides, hydrangenosides A, B, C and D, were isolated, along with the known iridoid glucosides loganin, secologanin, secologanic acid and sweroside. Moreover, hydrangenosides E, F, and G, the glucosides of the same class, were isolated together with hydrangenosides C and D from Hydrangea scandens. Based on spectroscopic and chemical methods, the novel structures of the new glucosides consisting of secologanin and a shikimate-malonate-derived unit which are joined by a C-C bond were elucidated. However, seven other Hydrangea plants were tested and found not to contain hydrangenoside-type glucosides.In 1964, Plouvier reported the isolation of loganin (10) from Hydrangea aspera D. DON, H . bretschneideri DIPP., and H . xanthoneura DIELS. [5]. However, no other study has been recorded on iridoid constituents of Hydrangea species (Saxijiragaceae) since then. We thus examined glucoside constituents of H . macrophylla (THUNB.) Ser. var. macrophylla, which is known to contain hydrangenol (8) [6] and hydrangenol glucoside (9) [7], and isolated four new secoiridoid glucosides, hydrangenosides A (l), B (2), C (3), and D (4) along with the known iridoid glucosides. In addition to these, hydrangenosides E (5), F (6), and G (7) of the same type of secoiridoid glucosides were isolated together with hydrangenosides C (3) and D (4) from the congeneric plant, Hydrangea scandens (LINN. fil.) SERINGE. We have established that the seven new secoiridoid glucosides have novel structures consisting of secologanin (11) and a shikimate-malonatederived unit, which are joined by a C-C bond. This paper deals with the structure elucidation of these glucosides.
