The aluminum chloride colorimetric method was used to determine the total content of flavonoids.
The total flavonoids content were determined using the method described in (Sun et al., 2011 )
with slight modifications. Briefly, 200 L of the extract or quercetin was mixed with 300 L of 5% sodium nitrite.
After 6 min, 500 L of 10% aluminum chloride was added, and the mixture was allowed to
stand for a further 5 min.
Then, 1000 L of 10% NaOH was added to the above mixture.
After the mixture had been incubated at room temperature for 15 min, the absorbance was measured at 510 nm.
Quercetin was used as standard. Results were expressed as mg/L of extract
and the mixture was allowed to stand for a further 5 min.