A new dimeric neolignan from Magnolia grandiflora L. seeds.

Bioassay-guided fractionation of the MeOH extract of Magnolia grandiflora seeds resulted in the isolation of a new dimeric neolignan, named bishonokiol A (1), as well as two known neolignans magnolol (2) and honokiol (3). The structures of the compounds were determined on the basis of data obtained using NMR and MS. Bishonokiol A (1) showed potent anti-proliferative activities in four human cancer cell lines, with IC50 values ranging from 5.1 to 7.5 µM. Additionally, bishonokiol A (1) induced apoptosis, as well as down-regulated the expression of the anti-apoptotic protein Bcl-2 and caspase-3 cleavage in HepG2 cell line.