Recently, compounds with an anthraquinone skeleton have been reported to have many interesting activities such as neuronal cell-protecting activity (espicufolin), anti-helpetic activity (AH-1763 IIa), and carbon clearance activity (SS43405E). We planned not only to prepare the bioactive anthraquinones and their analogs, but also to create highly active compounds by elucidation of their in vivo action mechanisms on neuronal cells.
In this research, we achieved the synthesis and absolute structure determination of espicufolin, the synthesis and absolute structure determination of SS43405E, and establishment of the synthetic routes to dihydroxyanthraquinones represented by K1115A. Racemic and S-espicfolins were subject to bioassay by using mouse embryonic neuronal cells. The espicufolins showed no protecting activity for the toxicity of glutamate but weak cytotoxiciry to the cells employed. In the synthetic approach for antihelpetic AH-1763 IIa, two different routes were examined, but total synthesis has not been achieved, yet. We now intended to prepare the side chain of AH-1763 IIa by asymmetric aldol condensation.