INHIBITION BY GUANIDINO COMPOUNDS OF THE GROWTH OF SPONTANEOUS MAMMARY-TUMORS IN SHN MICE

The D-form of lombricine extracted from the earthworm was previously f ound to inhibit the growth of spontaneous mammary tumours of mice. In the present study, the anti-mammary tumour effects of guanidino compou nds, of which structures resembled those of lombricine, ie., guanidine -sulfate (Guanidine), 2-guanidinoethanol sulfate (2-GEt), 4-guanidino- 1-butanol sulfate (4-GBt), guanidinoethylphosphate (GEP), opheline (OP HE) and the L-form of lombricine (L-Lom) were investigated in relation to their structures. In Experiment I, each guanidino compound was sus pended in olive oil at the concentration of 0.3mg/0.05ml, and was inje cted subcutaneously for 10 days to SHN mice bearing spontaneous mammar y tumours. 2-GEt, GEP, OPHE and L-Lom markedly inhibited mammary tumou r growth, but Guanidine and 4-GBt did not. In Experiment II, the two c ompounds examined 2-GEt and GEP, also significantly inhibited mammary tumour growth when given in drinking water (0.003%) for 10 days, while the effects were much weaker than those of the injected compounds. Th ese results indicate that the existence and the length of the ethylene group are important to antitumour activity and that the site of the a ntitumour activity in guanidino compounds is the guanidinoethyl group. These compounds are also suggested to be more effective when administ ered subcutaneously rather than intragastrically.