Synthesis and cytotoxic activities of goniothalamins and derivatives.

Substituted goniothalamins containing cyclopropane-groups were efficiently prepared in high yields and good selectivity. Antiproliferative activity was measured on three human cancer cell lines (A549, MCF-7, HBL-100), to show which of the structural elements of goniothalamins is mandatory for cytotoxicity. We found that the configuration of the stereogenic centre of the δ-lactone plays an important role for cytotoxicity. In our studies only (R)-configured goniothalamins showed antiproliferative activity, whereby (R)-configuration accords to natural goniothalamin (R)-1. Additionally, the δ-lactone needs to be unsaturated whereas our results show that the vinylic double bond is not mandatory for cytotoxicity. Furthermore, with a two-fold in vitro and in vivo strategy, we determined the inhibitory effect of the compounds to the yeast protein Pdr5. Here, we clearly demonstrate that the configuration seems to be of minor influence, only, while the nature of the substituent of the phenyl ring is of prime importance.