Screening of a series of 3,5-disubstituted 1,2,4-thiadiazoles for selectivity of cytotoxic action to cancer cells

New 3,5-disubstituted-1,2,4-thiadiazoles were synthesized and together with a series of their analogs obtained earlier were tested for cytotoxic activity to breast adenocarcinoma MCF-7 and lung carcinoma A 549 cells. The selectivity of cytotoxic action was determined in comparison to etiologically noncancerous breast epithelial cells MCF-10A and lung fibroblasts VA13. From five- to six-fold selectivity of cytotoxic action was revealed for 3,4-dichlorophenyl-{3-[2-(2-morpholin-4-ylethylamino)propyl]-[1,2,4]thiadiazol-5-yl}amine and (2-{5-[(4-diethylami-nobenzyl)pyridin-3-ylmethylamino]-[1,2,4]thiadiazol-3-yl}-1-methylvinyl)-(2,2,6,6-tetra-methylpiperidin-4-yl)amine in the pairs A 549/VA13 and MCF-7/MCF-10A, respectively. Some structure—property relationships for the compounds under study were discussed.