Inhibition of two human tumor cell lines by antimetabolites of coenzyme Q10.

5-Chloro-2,3-dimethyoxy-6-octylmercapto-1,4-benzoquinone (NSC 252188) and 2,3-dimethoxy-5-hydroxy-6-phytyl-1,4-benzoquinone (NSC 277818) inhibited the human cell lines 4265 and K 562c, and the experimental animal tumor line W256; they also showed antitumor activity against Walker carcinosarcoma 256 in rats with cures; they also inhibited the mitochondrial coenzyme Q10-enzymes, succinoxidase and NADH-oxidase. 5-Chloro-2,3-dimethoxy-6-n-dodecylmercapto-1,4-benzoquinone (NSC 220334) and 5-chloro-6-omega-cyclohexylhexylmercapto-2,3-dimethoxy-1,4-benzoquinone (NSC 238136) were also active against the K 562c cell line and showed cures against the Walker carcinosarcoma 256 in rats.