Antitumor effects of methylglyoxal-bis(N-4-methylthiosemicarbazone) and their potentiation in pyridoxine-deficient animals.

(S-180) by several bisthiosemicarbazones of a-ketoalde hydes was initially reported by French and Freedlander (5, 6). More recently, other compounds of this type have been found to cause marked inhibition of the growth of Walker carcinosarcoma 256 (W-256) and of two other transplantable rat tumors (19, 21). Striking antitumor effects were obtained using oral doses which were much lower than those causing toxicity to the host. The greater effectiveness of these compounds by the oral than by the intraperitoneal route was recognized (5, 6, 19, 21). Al though the mechanism of action of this group of com pounds has not yet been established, both theoretical considerations (5, 21) and experimental evidence (20) suggest that the chelating activity of the most potent among these bisthiosemicarbazones may be related to the antitumor effects observed. CH,-GMS was one of the most potent agents among