Four new polycyclic meroterpenoids from Ganoderma cochlear.

Four pairs of new polycyclic-meroterpenoid enantiomers, ganocins A-C (1-3) possessing a spiro[4,5]decane ring system, along with ganocin D (4) with an eight-membered ring, were isolated from the fruiting bodies of Ganoderma cochlear. Their structures were determined by spectroscopic data and X-ray diffraction crystallography. Their anti-AChE activities were evaluated, and a possible biogenetic pathway was also proposed.