2.5. Determination of Total Phenolic Content (TPC)
Total phenolic content of sample extracts was determined using Folin-Ciocalteu reagent as described by Singleton and Rossi (1965) and Song et al. (2010) One ml of the sample was thoroughly mixed with 5 ml Folin-Ciocalteu reagent. After 5 min, 4 mL of 7.5% sodium carbonate (Na2CO3) was added to the mixture and allowed to react for 2 hr at room temperature in the dark. The absorbance was measured at 765 nm using a microplate reader spectrophotometer (EPOCH Microplate Spectrophotometer, Vermont, USA).