Radioprotective effects of 2-imino-3-[(chromone-2-yl)carbonyl] thiazolidines against gamma-irradiation in mice.

A series of 2-imino-3-[(chromone-2-yl) carbonyl]thiazolidines substituted at the C-5 and/or C-7 positions of a chromone ring were synthesized. The in vivo toxicity and radioprotective efficacy of these agents were evaluated in male NMRI mice against cobalt-60 gamma-rays. The LD50 values as determined by a Probit analysis, were 659, 1216 and 790 mg/kg for compounds, 2, 3 and 4, respectively. For studying radioprotective effects, one half of the toxic LD50 values were used, namely 330, 605 and 395 mg/kg for compounds 2, 3 and 4, respectively. The dose reduced factor (DRF) was determined by dividing the LD50/30 values obtained from the radiation survival curve in the presence of a radioprotective agent by the LD50/30 value obtained from a control radiation survival curve. A compound with a hydroxyl group substituent at the C-5 position afforded better radioprotective activity than those without this substituent. The radioprotective effect of chromone having a hydroxyl group at only the C-7 position was similar to that of the unsubstituted chromone. The most active compound has hydroxyl groups at the C-5 and C-7 positions of the chromone ring; it had a DRF of 1.48.