Results
Spectrophotometric assays
The present research describes a Folin-Ciocalteu (FC)
method for the analysis and the quantification in fast
time. The fast method was validated in term of repeatability,
reproducibility, linearity, accuracy, optimised
analytical method were then conducted in order to
quantify phenolic compounds. Spectrophotometric
assays to determine the total flavonoid and polyphenol
contents of plant extracts were adapted for use with a
UV-VIS spectrophotometer (PG Instruments) and soft
UV WIN 5.05 to measure the absorbances of reference
solutions (QE and GA), and the absorbances of samples
from plant extracts [31]. Spectrophotometric assays for
the calculation of concentrations of quercetin (QE) were
based on absorbance measurements taken at 420 nm.
Spectrophotometric determination of gallic acid (GA)
content was calculated at 765 nm. The linearity of the
method was verified through the method of least
squares, which was applied in the concentration range
2-32 μg/mL for QE and 1-10 μg/mL for GA, with a correlation
coefficient R2 > 0.99. To verify the results, replicate
calibration curves were compared to the reference
substances for three consecutive days. A slight difference
was observed between the calibrations curves generated
for QE, whereas those for GA were nearly identical.