Two
new grayanoids, mollanol A (<b>1</b>) and rhodomollein XXV (<b>2</b>), were isolated from the fruits of Rhododendron
molle. Their structures were elucidated by spectroscopic
methods and X-ray diffraction analyses. Mollanol A (<b>1</b>) possesses a new C-nor-D-homograyanane carbon skeleton, while
rhodomollein XXV (<b>2</b>) is the first example of an 11,16-epoxygrayanane
and features a caged oxa-tricyclo[3.3.1.0<sup>3.7</sup>]nonane ring
system. Plausible biogenetic pathways for <b>1</b> were proposed.
Compound <b>1</b> exhibited transcriptional activation effects
on the <i>xbp1</i> upstream promoter in IEC-6, 293T, and
RAW264.7 cells