New seco-Prezizaane-Type Sesquiterpenes, Jiadifenin with Neurotrophic Activity and 1,2-Dehydroneomajucin from Illicium jiadifengpi

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Abstract
Two new seco-prezizaane-type sesquiterpenes, 1,2-dehydroneomajucin (1) and jiadifenin (2), were isolated from the methanol extract of the pericarps of Illicium jiadifengpi, indigenous to the southern part of China. Their structures were elucidated on the basis of NMR data. Compound 2, which is an equilibrated mixture of the epimers 2a and 2b on the C-10 acetal carbon, is the first example of a majucin-type seco-prezizaane with an oxo-function at the C-10 position. The proposed structure for 2 was unambiguously confirmed by chemical conversion of the known sesquiterpene (2S)-hydroxy-3,4-dehydroneomajucin (5) to 2. Compounds 2 and 5 were found to significantly promote neurite outgrowth in primary cultures of fetal rat cortical neurons at concentrations from 0.1 to 10 μM.