Synthesis and Anti-Cancer Activity Evaluation of Novel 1,3,4-Oxadiazole Substituted 5-Arylidene/Isatinylidene-2-Iminothiazolidin-4-Ones

Following the interaction of 2-chloro-N-(5-aryl-1,3,4-oxadiazole-2-yl) acetamides 1a-b with ammonium thiocyanate in dry acetone, the 5-unsubstituted 2-imino-4-thiazolidinones 4a-b have been synthesized. Compounds 4a-b were subsequently utilized in Knoevenagel condensation with aromatic aldehydes or isatin derivatives to synthesize the series of 5-arylidene/isatinylidene substituted 2-(1,3,4-oxadiazol-2-yl)imino-4-thiazolidinones 5a-h and 6a-d. The structures of target compounds were confirmed by using H-1 NMR spectroscopy and elemental analysis. Evaluation of anti-cancer activity in vitro for the synthesized compounds was performed following the National Cancer Institute protocol against leukemia, melanoma, lung, colon, CNS, ovarian, renal, prostate, and breast cancer cell lines. As a result, the most active compound 5a, namely 2-[5-(4-chlorophenyl)-[1,3,4]oxadiazol-2-ylimino]-5(4-methoxybenzylidene)thiazolidin-4-one was found to be a highly efficient anti-tumor candidate with average logGI(50) and logTGI values of -5.19 and -4.09, respectively.