Determination of total phenolics
The total phenolic content was determined using
Folin–Ciocalteu method (Mallick and Singh, 1980). In brief,
200 L of each solvent was mixed with 500 L of Folin–Ciocalteu
reagent. After 3 min incubation, 2 mL of 20% sodium carbonate
(Na2CO3) solution was added to each tube. The mixture was vortexed
and the tubes were placed in a boiling water bath for 1 min
and then were cooled. The absorbance was measured at 650 nm.
Gallic acid was used as a reference standard and the results were
expressed as (mg GAE)/g (milligramme Gallic acid equivalent per
gram) dry weight of plant extract.