spectrophotometer
at 760 nm. Standard gallic acid solutions were used
to prepare a calibration curve and results of total phenols were
shown as lg of gallic acid equivalents (GAE) per gram of sample.
Total flavonoids content was measured by the method reported
by Jia et al. [27] with some modification. Briefly, a known sample of
0.25 mL was mixed with 1.25 mL of de-ionized water and then a
75 lL solution of 5% (w/v) sodium nitrite was added and left it
for 6 min. After that, 150 lL solution of a 10% (w/v) AlCl3 solution
was added. After 5 min, 0.5 mL of 1 M NaOH was added. Then, distilled
water was added to make the final volume of 2.5 mL. The
absorbance at 510 nm was determined by a spectrophotometer.
The results were shown as lg of catechin equivalents per gram
of sample.
Total flavonols content was measured using the method reported
by Kumaran and Joel Karunakaran [28]. A known sample
of 2.0 mL was mixed with 2.0 mL solution of AlCl3 solution (2%,
w/v) and then 3.0 mL solution of sodium acetate (50 g/L) was
added in it. The mixture was placed at 20 C for 2.5 h. The same
procedure was carried out with standard. Spectrophotometer was
used to measure the absorbance at 440 nm and the results were
expressed as lg of quercetin equivalents per gram of sample.