Synthesis, Characterization, and In Silico Studies of Novel Spirooxindole Derivatives as Ecto-5'-Nucleotidase Inhibitors

Ecto-5'-nucleotidase (ecto-5'-NT, CD73) inhibitors are promising drug candidates for cancer therapy. Traditional efforts used to inhibit the ecto-5'-nucleotidase have involved antibody therapy or development of small molecule inhibitors that can mimic the acidic and ionizable structure of adenosine 5'-monophosphate (AMP). Herein, we report an efficient, environment friendly route for the synthesis of non-nucleotide based small molecules, i.e., substituted spirooxindole derivatives 9a-9l and investigated their inhibitory potential on human and rat recombinant ecto-5'-nucleotidase isozymes. These attempts have resulted in the identification of compound 9f (IC₅₀ = 0.15 ± 0.02 μM) inhibitor on h-ecto-5'-NT which showed 280-fold higher inhibition and compound 9h (IC₅₀ ± 0.19 ± 0.03 μM) on r-ecto-5'-NT with 406-fold enhanced inhibition than reference standard sulfamic acid. Moreover, in silico studies were carried out to assess binding interactions of potent compounds within enzyme active sites and demonstrated excellent correlation with the experimental findings.