Structure and Neurotrophic Activity of seco-Prezizaane-Type Sesquiterpenes from Illicium merrillianum

An extract of the pericarps of Illicium merrillianum has yielded four new sesquiterpenes: 3a-hydroxycycloparvifloralone (1), 1,2-dehydrocycloparvifloralone (2), (11) 7,14-ortholactone-3a-hydroxy-floridanolide (3), and 11-O-debenzoyltashironin (4) along with cycloparvifloralone (5), merrillianone (6), and tashironin (7). The structures of 1-4 were determined on the basis of spectroscopic analyses. 11-O-Debenzoyltashironin (4) showed neurotrophic activity in primary culture of rat cortical neurons at 0.1-10 μM. However, cycloparvifloralone-type sesquiterpenes (1, 2, 5, and 6) and tashironin (7) had no neurotrophic activity at these concentrations.