A new grayanane diterpenoid from Rhododendron decorum

A new grayanane diterpenoid, 2,3-epoxy-5β,6β,10α,13β,16α-pentahydroxy-grayanane, named craiobiotoxin IX (1), together with the known grayanotoxins I and IV, was isolated from the aerial part of Rhododendron decorum. The structure was elucidated on the basis of spectroscopic and X-ray diffraction analysis.