Stereoselective synthesis and antiproliferative effect of methoxylated spirooxindoles on colon cancer cell lines

Background: Safe and effective anticancer drug discovery is still a challenge for medicinal chemists. Spirooxindoles have shown promising pre-clinical results in designing newer cancer therapeutic candidates. In order to find out the effect of electron-withdrawing groups on its effect on colon cancer, a series of pyrrolizidine and N-methyl pyrrolidine spirooxindole derivatives were synthesized and evaluated against human colon cancer cell lines. Methods: A highly efficient one-pot, multi component and stereoselective [3+2] cyclo addition reaction were employed to synthesize a series of pyrrolizidine and N-methyl pyrrolidine spirooxindole derivatives with electron-withdrawing methoxy substitutions. This method involves previously optimized reaction condition developed in our lab to achieve excellent regio- and stereoselectivity. The newly synthesized spirooxindole derivatives were evaluated for their antiproliferative efficacy against human colon cancer cell lines HT29 and HCT116. Results: The synthesized compounds were characterized using FTIR, NMR, and ESI-MS. RP-HPLC determined the purity, and the structure while the assigned stereochemistry were confirmed using X-ray crystallography. Compound 14a produced the best antiproliferative activity with IC50 values of 62.66 and 18.48 µM against HT29 and HCT116 human colon cancer cell lines. Conclusion: The described one-pot, multicomponent, [3+2] cycloaddition reaction proved to be a catalyst-free reaction with high atom economy and single-step reaction. The effectiveness of the compounds was determined through in vitro cell viability assays which revealed their potency against colon cancer. Thus the study can be explored further as a hit-to-lead studies by designing compounds with varied substituents.