Synthesis, cytotoxicity and effects of some 1,2,4-triazole and 1,3,4-thiadiazole derivatives on immunocompetent cells.

Novel derivatives of 4,5-substituted-1,2,4-triazole-thiones and 2,5-substituted-1,3,4-thiadiazoles were synthesized and evaluated for their cytotoxicity. The biological study indicated that compounds 4-ethyl-5-(4,5,6,7-tetrahydro-1-benzothien-2-yl)-2,4-dihydro-3H-1,2,4-triazole-3-thione 13, N-ethyl-5-(4,5,6,7-tetrahydro-1-benzothien-2-yl)-1,3,4-thiadiazol-2-amine 16, 4-amino-5-(4,5,6,7-tetrahydro-1-benzothien-2-yl)-2,4-dihydro-3H-1,2,4-triazole-3-thione 20 and 4-amino-5-(5-phenylthien-2-yl)-2,4-dihydro-3H-1,2,4-triazole-3-thione 21 possessed high cytotoxicity in vitro against thymocytes. The corresponding IC(50) values were 0.46 microM, 5.2 x 10(-6)microM, 0.012 microM and 1.0 x 10(-6)microM. Most toxic against lymphocytes was compound 21, IC(50) - 0.012 microM. The tested compounds showed a general stimulation effect on B-cells' response.