Toxicological studies on bestatin. I. Acute toxicity test in mice, rats and dogs.

Studies on acute toxicities of bestatin (NK421) were carried out in both sexes of mice and rats, and male dogs. NK421 was administered subcutaneously, intraperitoneally and orally in mice and rats, and orally in dogs respectively. Mice and rats were observed for 14 days after treatment and LD50 values were calculated by the probit method. NK421 showed very low toxicity and no death occurred in any species following the oral administration of the maximum dose capable of dosing such as 4 g/kg for mice, 2 g/kg for rats and 1.2 g/kg for dog. General toxic signs seen in mice and rats following subcutaneous and intraperitonial injections were as follows; depression, suppressed movement, piloerection, inhibition of spontaneous movement, anorexia and emaciation. Death occurred within 5 days after administration. The toxic target organs of NK421 were found to be kidney, lymphoid tissue and liver based on histopathological examination of dead animals.