Radioprotective action of thiadiazole derivatives
Continuing previous investigations on the search for radioprotectors among the sulfurcontaining heterocycles [i, 2], we synthesized and studied the radioprotective properties of derivatives of 1,3,4and 1,2,4-thiadiazoles with various substituents: amino groups, alkyls, and mercapto groups. The following thiadiazole derivatives were investigated: 2alkylamino-5-alkyl-l,3,4-thiadiazoles and their methiodides (I-VII); 2-alkylamino-l,3,4thiadiazole-5-thiones (VIII-XII); 2-alkylamino-5-alkylmercapto-l,3,4-thiadiazoles (XIIIXVIII); 2,5-diamino-l,3,4-thiadiazole and its methiodide (XIX, XX), and 1,2,4-thiadiazoles (XXI-XXIII).
Synthesis of New 1,3,4-Thiadiazole and 1,2,3,4-Oxathiadiazole Derivatives from Carbohydrate Precursors and Study of Their Effect on Tyrosinase Enzyme
5-(1,2,3,4-Tetrahydroxybutyl)-2-methylfuran-3-carbohydrazide (2) was condensed with a variety of ketones to afford carbohydrazide derivatives 3–6. Acetylation of 3–5 afforded the acetyl derivatives 7–9, while periodate oxidation of 3–6 afforded the formyl derivatives 10–13. Acid catalyzed condensation of thiosemicarbazide or o-tolylthiosemicarbazide with the prepared aldehydes 10–12 gave thiosemicarbazone derivatives 14–19. Cyclization of the latter with acetic anhydride afforded 4,5-dihydro-1,3,4-thiadiazolyl derivatives 20–25. On the other hand, condensation of p-tosylhydrazine with the prepared aldehydes 10–12 afforded p-tosylhydrazone derivatives 26–28. Cyclization of 26–28 with acetic anhydride afforded 1,2,3,4-oxathiadiazole derivatives 29–31 respectively. Moreover, the obtained results regarding to the effect of some of the prepared compounds on tyrosinase enzyme showed that the majority of these compounds having an inhibitory effect; especially compounds 12, 16, 17, and 28.
The effect of body temperature on the sensitivity of the haemopoietic tissues of mice to x-irradiation.
SummaryThe effect of x-irradiation on the haemopoietic tissues of mice while they are at body temperatures of 15°c is described.Histological examination of the spleen and femoral bone-marrow revealed no differences between groups of animals irradiated at body temperatures of 15°c and those irradiated at normal body temperatures and then cooled to 15°c over the dose-range 0 to 950 r.The total peripheral-leucocyte counts were compared with those obtained in previous experiments when animals were irradiated at body temperatures of 1°c and at normal body temperatures. Statistical analysis shows that on the evidence of leucocyte counts five days after irradiation, exposure of animals to x-rays while they are at body temperatures of 15°c affords slight protection to the haemopoietic tissues, which is much less than the protection provided at body temperatures of 1°c when the animals are severely hypoxic. Cooling to 15°c after irradiation affords no detected radioprotection.