Determination of Total Phenolic Content

Total phenolic content of the plant extracts was determined by the Folin-Ciocalteu (FC) reagents using gallic acid as a standard (Hazra et al., 2008 (link); Mishra et al., 2015 (link)). Different concentrations of the plant extracts (50–1000 μg ml^-1) were mixed with 2.5 ml 0.2 N Folin–Ciocalteu reagent (Sigma-Aldrich, USA) and were incubated for 5 min, followed by the addition of 2 ml sodium carbonate (Na₂CO_3; 75 g l^-1). The reaction mixtures were incubated for a further 90 min at room temperature. The absorbance was measured at 760 nm and the total phenolic content was calculated as mg ml^-1 gallic acid per 100 mg extract from a standard curve.