Grayanane diterpenoids from the leaves of Craiobiodendron yunnanense

Ten new grayanane diterpenoids, craiobiotoxins I-VIII (1-8) and craiobiosides A (9) and B (10), and five known grayanane diterpenoids, grayanotoxin XVIII, lyoniol A, lyoniol B, pieristoxin H, and grayanoside B were isolated from the leaves of Craiobiodendron yunnanense (Ericaceae). The structures of 1-10 were elucidated by spectroscopic methods including various 2D NMR and X-ray crystal diffraction experiments. In biological testing of our isolates, craiobiotoxin III (3) and lyoniol B showed moderate antifeedant activity.