2.6.1. 2,2-diphenyl-1-picrylhydrazyl Radical Scavenging activity (DPPH)

DPPH radical scavenging activity of crude extracts was examined based on a previously described method by Siddharth and Rai [22]. Crude extracts at varying concentrations (7.81–1000 μg/mL) were reacted with freshly prepared DPPH in methanol (60 mM, Sigma, USA). Reaction mixture was incubated at room temperature for 30 min in the dark prior to the measurement of absorbance at 520 nm. The radical scavenging activity was expressed as IC50 (μg/mL). The percentage scavenging of DPPH radicals was computed by the following equation:

$$\text{DPPH sævænging effect} \left(\%\right) = \left[ (\text{A}\_{\text{o}} - \text{A}\_{1}) / \text{A}\_{\text{o}} \right] \times 100 \tag{1}$$

where, Ao = Absorbance of control, A1 = Absorbance of crude extracts. Trolox (Sigma) was used as a reference compound whereas methanol was used as blank.

2.6.2. 2,2 -Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) Radical Scavenging Activity (ABTS)

ABTS radical scavenging activity was performed according to the method developed by Ser et al. [23] with slight modifications. Crude extracts at concentrations (7.81–1000 μg/mL) were mixed with ABTS (Sigma, USA) cation complex and incubated in dark at room temperature for 30 min. The absorbance was measured at 415 nm. The radical scavenging activity was expressed as IC50 (μg/mL). The percentage inhibition of ABTS\*<sup>+</sup> radicals were computed by using following equation:

$$\text{ABTS}^{\*+} \text{scavenging effect (\%)}=[(\text{A}\_{\text{o}}-\text{A}\_{\text{l}})\text{A}\_{\text{o}}] \times 100\tag{2}$$

where, Ao = Absorbance of control, A1 = Absorbance of crude extracts. Trolox (Sigma) was used as a positive reference.
