Total phenolic content
The total phenolic content of the extracts was determined
according to the Folin–Ciocalteu method adjusted to a microscale
(Arnous et al., 2001). In a micro-tube, 1100 mL of distilled water,
15 mL of sample dissolved in methanol, and 75 mL of Folin–
Ciocalteu reagent were mixed. After 1 min, 310 mL of 20% aqueous
of Na2CO3 was added, and the mixture was mixed and allowed to
stand at room temperature in the dark for 120 min. The absorbance
was read at 750 nm, and the total phenolic concentration was
calculated from a calibration curve using gallic acid as standard.
The results are expressed as milligrams per litre of gallic acid
equivalents (mg/L GAE).