Antitumor organometallics. I. Activity of some diphenyltin(IV) and diphenylantimony(III) derivatives on in vitro and in vivo Ehrlich ascites tumor.

Diphenyltin(IV) and diphenylantimony(III) derivatives of dithiophosphorus ligands, i.e. Ph2Sn(S2PPh2)2 (1), Ph2Sn[S2P(OPr)2]2 (2), Ph2SbS2PPh2 (3) and Ph2SbS2P(OPri)2 (4), have been tested in vitro and in vivo against Ehrlich ascites tumor. All four compounds were almost equally effective in vitro, exhibiting inhibitory effects on cell proliferation, viability and protein synthesis, and exacerbated respiration and Ca-ATPase activity. In mice bearing Ehrlich ascites tumor cells, all four compounds inhibited the tumor growth, the organometallic phosphorodithioates being more active than phosphinodithioate analogues, and the organoantimony derivatives more active than organotins. Compound 4 (5 mg/kg/day, i.p., on days 1,3 and 5) produced an increase in life span of 83% and a cure rate of 30% in mice bearing this tumor.