THE RADIOPROTECTIVE EFFECT OF A NEW AMINOTHIOL (20-PRA)

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