Lyonin A, a new 9,10-Secograyanotoxin from Lyonia ovalifolia.

Phytochemical studies on the branches and leaves of Lyonia ovalifolia yielded a new grayanane diterpenoid, lyonin A (1), together with two known compounds, secorhodomollolides A and D (2 and 3, resp.). The structure of 1 was elucidated by combination of 1D- and 2D-NMR, and MS analyses. Compound 1 turned out to be a new, highly O-acylated grayanane diterpenoid, of which ring B has undergone an oxidative cleavage between C(9) and C(10), yielding a system differing from the previously reported grayanane type with a 5/7/6/5 ring system. Results of the cAMP regulation activity assay showed that compounds 2 and 3 at 50 μM induced a significantly decreased cAMP level in N1E-115 neuroblastoma cells (p<0.001), indicating neuropharmacological potential.