Synthesis of seleno- and thio-guanine-Pt (II) complexes and their antitumor activity in mice.

Selenoguanine- and selenoguanosine-platinum(II) complexes were synthesized, and their atitumor activities against L1210 in mice and against in vitro tissue culture system were studied. These compounds exhibited antitumor activity of medium strength and showed very low toxicity. The effect of the SeG-Pt (II) complex in mice was retained longer than that of the parent compound SeG because the SeG-Pt (II) complex very slowly released SeG into blood.