Total flavonoid content
The total flavonoid content was estimated by the method
developed by Jia et al[16]. Briefly, 0.3 mL of 5% (w/v) NaNO2
was added to every 4 mL of extract solution of varying
concentrations. After 5 min of incubation, 0.3 mL of 10% (w/
v) AlCl3 was added. After 6 min, 2 mL of 1 mol/L NaOH was
added. The total volume was made up to 10 mL with distilled
water. After vortex shaking for 1 min, the absorbance was
noted at 510 nm. The total flavonoid content was reported in
terms of µmole of quercetin equivalents/g of extract.
To this solution, 1 mL of 0.1% ferric chloride was added
and absorbance was measured at 700 nm. Butylated
hydroxyanisole (BHA) was used as a standard.