Chromosome protection by WR-2721 and MPG-single and combination treatments.

The radioprotective action of thiol compounds 2-mercaptopropionylglycine (MPG) and S-2(aminopropylamino) ethyl phosphorothioic acid (WR-2721) was evaluated either alone or in combination on the bone marrow chromosomes of Swiss albino mice after 4.5 Gy of 60Co radiation. Single drug administration of WR-2721 at 300 mg/kg body weight resulted in a 50% reduction in the yield of aberrant cells at 24 hours post irradiation, while the other single drug doses were less effective. The combination of the two drugs increased the effect in the sense that 150 mg/kg WR-2721 with 20 mg/kg MPG gave equal protection as 300 mg/kg WR-2721 given alone. Moreover, on day 14, when WR-2721 produced an increase in the precent aberrant cells the above combination brought down the value to normal. It appears that MPG neutralizes to some extent the toxic effect of WR-2721, without impairing the protective efficiency.