Dysidiolide (1), a novel sesterterpene from the Caribbean marine sponge Dysidea etheria de Laubenfels, inhibits the protein phophatase cdc25A (IC_<50>=9.4μM) that promotes the Gl/S transition of the cell cycle by dephosphorylation of the cyclin/CDK complex. Cdc25A is known to be oncogenic and overexpressed in a number of tumor cell lines. Therefore, cdc25A inhibitor dysidiolide is regarded as a novel candidate agent for the treatment of cancer and other proliferative diseases. Although some groups accomplished total synthesis of dysidiolide, a synthetic approach to its struture-activity relationship has not been reported yet. We developed an efficient synthetic route to dysidiolide and its analogs in order to investigate the structure-activity relationship. The retrosynthetic analysis is shown in scheme 1. The octalin framework was constructed by intermolecular Diels-Alder reaction of the chiral triene (5) with crotonaldehyde (scheme 3). Subsequently, the quaternary center at C6 was created by methylation of the exocyclic enolate (scheme 4). Finally, the γ-hydroxybutenolide residue was introduced by addition of 3-furyllithium to the aldehyde (2) and successive photochemical oxidation of the furan ring. A series of dysidiolide analogs were synthesized according to the same procedures. To investigate the structure-activity relationship of dysidiolide, dysidiolide and its analogs were examined for cdc25A/B inhibitory activity and antiproliferative activity (table1). Searching for simple and strong cdc25A inhibitors, we designed and synthesized novel cdc25A inhibitors using Windaus-Grundmann ketone derived from Vitamin D3 (figure 1, table 2). Finally, to comfirm the effect of cdc25A inhibitors on cell cycle progression, cell cycle analysis was performed (figure 2).
