Toxicity Testing of Flowers of Neem Tree (Azadirachta indica A. Juss)

Flowers of neem (Azadirachta indica A. Juss) possess a strong cancer chemopreventive potential in rats as well as antimicronucleus formation in mice. However, toxicity testing has never been evaluated. This study was aimed to determine its acute and subacute toxicities in Wistar rats. Acute toxicity was conducted by feeding methanol extract of neem flowers (MENF) suspending in 20% propylene glycol at 6, 9 and 12 g/kg bw. On the other hand, subacute toxicity testing was carried out by feeding MENF suspending in 0.5% tragacanth at 150, 750 and 1,500 mg/kg bw for 90 consecutive days. Hematology, blood chemistry and histopathology were evaluated at the end of the experiment. The results demonstrated that MENF had LD50 value higher than 12 g/kg bw. In subacute toxicity study, MENF caused a significant decrease in the growth of male, but not female rats, but significantly increased the relative liver weights of those receiving MENF at 750 and 1,500 mg/kg bw. Blood chemistry values of most rats were within normal ranges. However, ALP, creatinine and potassium values were significantly higher in female group receiving MENF at 750 mg/kg bw while in male rats, the levels of AST and BUN were lower but that of creatinine was higher than those of the control groups. Histopathological examination of visceral organs showed no significant change. In conclusion, LD50 value of MENF in rats was greater than 12 g/kg bw (similar to 800 times of human use). Subacute toxicity testing at 750 and 1,500 mg/kg bw (similar to 50 and 100 times of human use) showed the effects on some biochemical parameters.