Measurement of total polyphenol content in TBE

Total polyphenol was measured using the Folin-Ciocalteu method as described previously.^(23,24) Briefly, TBE (100–200 mg) in 50% ethanol was solubilized using a sonicator. After addition of the Folin-Ciocalteu reagent to the filtrate, the reaction mixture was analyzed by absorbance at 660 nm. Catechin was used as the standard sample to construct the calibration curve.