Synthesis and cytotoxicity of methyl-and methoxy-substituted metal 8-quinolinethiolates

It has been found that the nature of the substituent, its position in the quinoline ring, and the nature of the metal significantly affect the antitumor activity and toxicity of metal 8-quinolinethiolates. The most cytotoxic towards human fibrosarcoma HT-1080 and mouse hepatoma MG-22A tumor cells are the 6-methoxy-8-quinolinethiolates of rhodium, osmium, iridium, indium, antimony, and bismuth, however these are highly toxic towards normal mouse embryonic NIH 3T3 fibroblasts. The iridium 5-methyl-8-quinolinethiolate is somewhat less active to MG-22A cells but shows quite good selectivity of action because of its markedly lower toxicity.