Treatment of sulfamethoxazole (SMZ ) (1) with different aromatic aldehydes 2a-f within few minutes (5-8 min) afforded the corresponding Schiff bases 3a-f which were subjected to react with thioglycolic acid (4) under refluxing toluene/dimethlformamide (DMF) in (1:1) ratio for 12-17 h, yielded N-(5-methylisoxazol-3-yl)-4-(4-oxo-2-phenyl-1,3-thiazolidin-3-yl)benzenesulfon- amide derivatives 5a-f. On the other hand, the same products 5a-f were obtained when SMZ (1) was treated with a mixture of the same aromatic aldehydes 2a-f and thioglycolic acid 4 via one-pot, three-component reaction under microwave irradiation. The key advantages of this process were high yields 79-88%, shorter reaction times 6-11 min., easy work-up, and problems associated with toxic solvent use (cost, safety, pollution) were avoided. The structures of newly compounds were elucidated by elemental and spectral analyses. Three compounds 5a, 5b and 5f were tested for cytotoxicity against four human cancer cell lines MCF-7, HePG2, HCT 116 and 116 PC-3. Compound 5b exhibited the most potent cytotoxic properties on HePG2 and PC-3. Furthermore, it showed inhabitory effect against MCF-7 and HCT 116 cells.
 KEY WORDS: Sulfamethoxazole, 4-Thiazolidinones, Schiff bases, Multicomponent reaction, Microwave, Traditional methods and cytotoxicity
 Bull. Chem. Soc. Ethiop. 2024, 38(2), 481-491. 
 DOI: https://dx.doi.org/10.4314/bcse.v38i2.15