Synthesis of chiral hydroxylated enones as potential anti-tumor agents.

A series of chiral hydroxylated enones were synthesized as COTC ether analogues to investigate the structural features required for optimal and selective anti-tumor activity. The cytotoxicity of the seven COTC ether analogues against WRL-68 normal and HepG2, HL-60 cancer cell lines were measured. C-4 ether analogues with an aliphatic chain substituent were found to be more favorable than their aromatic counterparts. Inversion of the configuration at C-4 in 5e to give 5f only resulted in reduced selectivity towards cancer cells. These results show that 4-O-pentyl-gabosine D (5e) has optimum selectivity and cytotoxicity towards two cancer cell lines.