Abstract:

OBJECTIVE:To evaluate the acute toxicity and mutagenicity of potassium 2-(1-hydroxypentyl)-benzoate(dl-PHPB). METHODS:KM mice were intravenously treated with dl-PHPB at the doses of 256.0、286.3、320.0、357.8、400.0 and 447.2 mg/kg. We observed the clinical signs of toxicity and calculated the median lethal dose (LD₅₀) and LD₅₀ 95% confidence interval. Mutagenicity of dl-PHPB was studied by Ames test, bone marrow micronucleus study in male mice and in vitro CHL cell mammalian chromosome aberration assay. In Ames test, the tester strains used were Salmonella typhimurium TA97, TA98, TA100 and TA102, mutagenicity was evaluated with the plate incorporation method beginning at 0.5, 5, 50, 500 and 5 000 μg per plate in the absence or presence of S9 metabolic activation. In bone marrow micronucleus study, KM male mice were intravenously treated with dl-PHPB at the dosse of 210、70 and 23.3 mg/kg. Bone marrow cells were harvested from mice at 24 hours after dosing. 1 000 PCEs per animal were examined microscopically for the presence of micronucleated polychromatic erythrocytes(MNPCEs). The in vitro CHL cell mammalian chromosome aberration study on dl-PHPB consisted of the premilinary toxicity assay and chromosome aberration assay, with and without S9 metabolic activation system, and chromosomal aberration percentage per dose were analyzed. RESULTS:In the acute toxicity study, all mice after dosing developed transient toxic symptoms such as tachypnea, sautonomic activity decreased, prostration, then the dying state were observed at dosage of ≥320.0 mg/kg, mice appeared respiratory depression, cyanosis, loss of righting reflex, and died during 2 to 30 minute after administration. The mortality rate of mice treated with dl-PHPB from 256.0 to 447.2 mg/kg were 0, 0, 10%, 30%, 70%, 100%, respectively. The survival mice returned to normal after 30 min. In the 14-days observation period, there were no abnormal clinical signs in the surviving animals and the general autopsy showed no abnormality in major organs. The intravenous median lethal dose of dl-PHPB was 373.3 mg/kg in mice, LD₅₀ 95% confidence interval was 355.6 to 392.0 mg/kg. In the Ames assay, no positive mutagenic response was observed. In bone marrow micronucleus study, a single bolus intravenous administration of dl-PHPB at dosages of 23.3, 70 and 210 mg/kg didn't induce a significant increase in the number of MNPCEs in the bone marrow, MNPCEs were less than 4‰ at three dosages. In CHL chromosome aberration assay, dl-PHPB achieved a chromosome aberration of less than 5% in the presence and absence of S9 mixture. CONCLUSION:The intravenous median lethal dose of dl-PHPB was 373.3 mg/kg in mice, and dl-PHPB was not mutagenic in these 3 screening mutation assays.

Key words: anti-cerebral ischemic candidate drug, potassium 2-(1-hydroxypentyl)-benzoate, acute toxicity, mutagenicity