2.6. Assessment of antioxidant activity
2.6.1. Radical scavenging activity
The antioxidant activity was assessed through various in vitro assays. The free radical scavenging activities of the three extracts of A. squamosa leaves and l-ascorbic acid (vitamin C) were measured in terms of hydrogen donating or radical scavenging ability using the stable 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals. Nitric acid generated from sodium nitroprusside was measured by the Griess reaction. The antioxidant activity was further confirmed by hydrogen peroxide (H2O2) scavenging and reducing power properties of A. squamosa leaves extracts.
The percentage scavenging of free radical activity was calculated using the following formula:
(1)% inhibition = [(Control – Test)/Control] × 100
The half-maximal inhibitory concentration (IC50) values were determined as the concentration of the test mixture that gave 50% reduction in absorbance from that of the control.