The total phenolic content of the natural extract samples was determined
spectrophotometrically, by the Folin–Denismethod, according to
Waterman andMole (1994). An aliquot (100 μl) of sample solution was
mixedwith 8.4 ml of ultrapurewater in a test tube, and 0.5ml of Folin–
Denis reagent was added. After 1 min, 1 ml of Na2CO3 solution (10%)
was added and the solution was allowed to stand for 30 min at room
temperature. Absorbance of the resulting blue complex was measured
at 760 nm in a dual-beam spectrophotometer (Uvikon XL, Bio-Tek Instruments,
Milan, Italy). All determinations were made in triplicate.
The total phenolic content of the samples was determined by comparison
against the standard curve of commercial gallic acid, and expressed
as gallic acid equivalents (GAE).