Synthesis of new chalcone-based homoserine lactones and their antiproliferative activity evaluation

Three series of new homoserine lactone analogs were efficiently synthesized starting from methionine and further evaluated for their antiproliferative activity against different cancer cell lines. Among these compounds, some of the chalcone containing compounds 6a-n showed acceptable antiproliferative activity against prostate cancer cells DU145 and PC-3 with the IC₅₀ values less than 10 μM. Compounds 6c, 6e and 6h inhibited growth of DU145 and PC-3 cells at low micromolar levels with the IC₅₀ values ranging from 3.0 to 5.0 μM, much more potent than natural OdDHL. Compound 6e concentration-dependently inhibited colony formation and cell migration of DU145 cells. A synergistic effect on the growth inhibition and the apoptosis of DU145 cells was observed when compound 6e was used in combination with TRAIL. OdDHL or 6e treatment concentration-dependently activated TRAIL death receptor DR5 which may account for the observed synergistic effect of 6e or OdDHL with TRAIL on the growth inhibition and cell apoptosis. Compound 6e also inhibited migration of DU145 cells in a time- and concentration-dependent manner. The data suggest that quorum sensing molecules OdDHL and 6e may improve the sensitivity of DU145 cells toward TRAIL via activating DR5, compound 6e may be used as a potential lead compound for developing new TRAIL receptor agonists.