RESUMO
We examined the radioprotective effect of aminothiol 2-N-propylamine-cyclo-hexanethiol (20-PRA) on a human leukemic cell line (K562) following various radiation doses (5, 7.5 and 20 Gy) using a source of (60)Co gamma-rays. At 5 Gy and 1 nM 20-PRA, a substantial protective effect (58 per cent) was seen 24 h after irradiation, followed by a decrease at 48 h (11 per cent). At the high radiation dose (20 Gy) a low protective effect was also seen (35 per cent). In addition, the antitumorigenic potential of 10 nM 20-PRA was shown by the inhibition of crown gall formation induced by Agrobacterium tumefaciens. The radioprotective potency of 20-PRA is 10(5)-10(6) times higher than that of the aminothiol WR-1065 N-(2-mercaptoethyl) - 1,3-diaminopropane) whose protective effect is in the 0.1 to 1.0 mM range.