3. Results
3.1. Total phenolic content
The total phenolic content of the aqueous extract of I. tinctoria was determined using the Folin–Ciocalteu reagent and expressed as gallic acid equivalent per gram of plant extract. The total phenolic content of the test fractions was calculated using the standard curve of gallic acid (y=0.454x+0.139; R2=0.0997). Aqueous extract of I. tinctoria was found to have 267.2±2.4 mg/g phenolic content.
3.2. Total flavonoid content
Aluminum chloride colorimetric methods were used to determine the total flavonoid content of the aqueous extract of I. tinctoria. Total flavonoid content was calculated using the standard curve of quercetin (y=0.494x−0.038; R2=0.977) and expressed as quercetin equivalent per gram of the plant extract. Aqueous extract of I. tinctoria was found to have 75.43±3.3 mg/g flavonoid.
3.3. Total antioxidant capacity
The total antioxidant capacity of aqueous extract of I. tinctoria was evaluated by the phosphomolybdenum method and expressed as ascorbic acid equivalent per gram of plant extract. The total antioxidant content of the test samples was calculated using the standard curve of ascorbic acid (y=0.0014x+0.0114; R2= 0.9926), and found to be 349.11±8.0 mg/g.
3.4. DPPH free radical scavenging activities
The free radical scavenging activities of aqueous extract of I. tinctoria were studied by its ability to reduce DPPH, a stable free radical; and any molecule that can donate an electron or hydrogen to DPPH can react with it and thereby bleach DPPH absorption. DPPH is a purple dye with absorption maxima at 517 nm, and upon reaction with a hydrogen donor the purple color fades or disappears due to conversion of it to 2,2diphenyl-1-picryl hydrazine, resulting in decrease in absorbance. The DPPH scavenging effect was found to increase with increased concentrations. At 250 μg/mL, aqueous extracts showed 51.08% inhibition and ascorbic acid showed 92.02% inhibition (Fig. 1). IC50 values were calculated and expressed (Table 1).