2.4.2. DPPH Scavenging Activity

The antioxidant activity of the biosurfactant was also evaluated using the free radical sequestration method based on hydrogen donation using the stable 2,2-diphenyl-1 picrylhydrazyl radical (DPPH• ) [20]. The measurements were performed in triplicate and the inhibition activity was calculated based on the percentage of DPPH• scavenged. The vitamin E analogue 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox) and butylated hydroxytoluene (BTH) were used as standards. The percentage of inhibition (I%) was calculated using the equation:

$$\text{I\%} = \frac{\text{A}\_{\text{c}} - \text{A}\_{\text{s}}}{\text{A}\_{\text{c}}} \times 100 \tag{1}$$

in which Ac is the absorbance of the control and As is the absorbance of the sample.
