The radioprotective effects of a new 1-isobutanoil-2-isopropylisothiourea derivative named T1082 are presented. Research methods included toxic characteristics, radioprotective activity (Till-McCulloch's test and 30-day survival test) in γ-ray total-body-irradiated mice, and a clinical and histological study of the effect of T1082 on acute radiation skin reactions (RSR) in rats after a single or fractionated β-ray local irradiation. T1082 is more effective than its analogue, the NOS inhibitor T1023, at low concentrations and doses (1/12-1/8 LD10), both parenterally and intragastrically. In this case, its therapeutic index (LD50/ED50) reaches 30, and the optimal radioprotective doses (ED84-98-141-224 mg/kg) are an order less than the maximum tolerated doses-1/16-1/10 LD10. These properties allowed T1082, at a low intragastrical dose (160 mg/kg; 1/14 LD10), to significantly limit the severity of acute RSR after single (40 Gy) and fractionated (78 Gy) β-ray irradiation. The results confirm T1082 as one of the safest emergency radioprotectors and indicate the prospects for its further development as a pharmacological agent for the prevention of RT complications.
Keywords: pharmacological safety; radiation-induced tissue toxicity; radiotherapy; selective radiation protection.