Highly acylated diterpenoids with a new 3,4-secograyanane skeleton from the flower buds of Rhododendron molle.

Four highly acylated diterpenoids with a new 3,4-secograyanane skeleton, secorhodomollolides A-D (1-4), have been isolated from the flower buds of Rhododendron molle. Their structures including absolute configurations were determined on the basis of spectroscopic data interpretation and single-crystal X-ray crystallography. Compound 4 exhibited significant analgesic and sedative effects at a dose of 5 mg/kg, and compound 2 showed selective cytotoxic activity against human hepatoma carcinoma cell line (Bel-7402) with IC(50) 0.97 microM.