Simonols A and B, two novel sesqui-neolignans from the fruits of Illicium simonsii

Two new sesqui-neolignans with novel conjugation way, simonol A (1), featuring a unique motif of a 5,5-dihydro-pyran with a hemiketal carbon, while simonol B (2) possessing two dihydronfuran rings in the same direction, were isolated from the ethanol extract of the fruits of Illicium simonii. Their structures were elucidated by spectroscopic methods including 1D and 2D NMR, HRESIMS, and calculation of electronic circular dichroism (ECD) using density functional theory (DFT). The two isolates were evaluated for their inhibitory activities against the growth of four lines of human cancer cells (NCI-H460, SMMC-7721, MCF-7, BGC-823): 1 showed strong activities comparable to 5-Fluorouracil, and 2 to a less content. In addition, plausible biosynthetic routes for the two compounds were also proposed.