Introduction: Nowadays, a group of inorganic compounds, knowing as polyoxometalates, considered to have potential applications in medicine due to their antibacterial, antitumoral, antiviral and anti-diabetic activities. These compounds are complexes of early transition metals (such as molybdenum, tungsten and vanadium) and oxygen in different structures. The purpose of present study was to evaluate toxicity study of a newly synthetized polyoxomolibdate: (NH4)12[Mo36 (NO) 4 O108 (H2O) 16] in Wistar rats. Materials and methods: four groups of male Wistar rats (n=5) were used in the present study. One group received saline (as the vehicle of polyoxomolibdate) and the other three groups received one daily injection of polyoxomolibdate (25, 50 and 75 mg/kg. i.p.) for 14 consecutive days. On day 15 of the experiments, the animals were anesthetized with ketamine (70mg/kg) and xylazine (10 mg/kg) and blood and serum samples were harvested for assessment of blood parameters, liver enzymes, urea and creatinine. Results: No death occurred in the rats that received different doses of the compound during the 14 days period of the experiments, but the weight of animals that received high doses of polyoxomolibdate decreased compared to the saline treated animals. Analysis of biochemical parameters showed that AST, ALT urea and creatinine but not ALP were increased in the rats that received high dose of the compound compared with those rats that received saline. Moreover, assessment of blood parameter showed a decrease in hematocrit, MCV, and MCH in the compound-treated animals. Conclusion: The newly synthesized polyoxomolibdate has some toxic effects on the liver, kidney and blood. Therefore, it can be concluded that at least in the high dose that were used in the experiments, this compound is not safe.
