The present study was undertaken to determine the optimum effective dose, dose reduction factor (DRF) and possible mechanism of action of Aloe gel. Three different doses of gel (250, 500 and 750 mg/kg body weight) were tested against 8 Gy induced damage in Swiss albino mice. A dose of 750 mg/kg body weight of Aloe was found the most effective while, 250 mg/kg body weight was the least effective in providing protection, as observed in the form of higher concentrations of blood GSH and vitamin C and lower level of serum LPO than irradiated animals at 1h post irradiation and higher percent of survivors up to day 30 post irradiation. Treatment of mice with Aloe before irradiation with different doses of gamma radiation (6-12 Gy) delayed the onset and reduced the severity of signs of radiation sickness. The LD(50/30) was calculated as 6.77 and 10 Gy for untreated irradiated and Aloe treated irradiated animals, respectively and its dose reduction factor was also calculated as 1.47. Aloe gel scavenged the free radicals, DPPH•, ABTS(+•) and NO in a concentration dependent manner in vitro and therefore, scavenging of free radicals seems to be its important mechanism of action.
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