Figure 4.

The ability of the aqueous extract from Aloe vera leaves and ascorbic acid, used as a reference antioxidant to inhibit the generation of superoxide radical by xanthine/xanthine oxidase system was estimated as a function of increasing extract (from 0.5 to 5 mg/ml) and ascorbic acid (from 0.05 to 0.25 mg/ml) concentration and by recording the decrease in absorbance at 560 nm. The results were expresed as percent inhibiton of NBT reduction by the extract (from 10.2 ± 1.33 to 62.72 ± 2.06%) and ascorbic acid (from 6.63 ± 1.23 to 62.06 ± 1.44%), derived from three separate assays. No difference was observed between the superoxide radical scavenging activities of the extract at 5 mg/ml and ascorbic acid at 0.25 mg/ml, p > 0.05.