(±)-Ganoapplanin, a Pair of Polycyclic Meroterpenoid Enantiomers from <i>Ganoderma applanatum</i>

(±)-Ganoapplanin (<b>1</b>), a pair of novel meroterpenoid enantiomers featuring an unprecedented dioxaspirocyclic skeleton constructed from a 6/6/6/6 tetracyclic system and an unusual tricyclo­[4.3.3.0<sup>3′,7′</sup>]­dodecane motif, were isolated from <i>Ganoderma applanatum</i>. Its structure and absolute configurations were determined by spectroscopic analyses, X-ray crystallography, and ECD (electronic circular dichroism calculations). A plausible biogenetic pathway, involving a key Gomberg–Bachmann reaction, was also proposed for (±)-<b>1</b>. Biological studies showed that (±)-<b>1</b> and its enantiomers exhibited different inhibitory activities on T-type voltage-gated calcium channels.