Polyphenol Content Determination Protocol

Polyphenol contents of FP and BP extracts were determined using the Folin-Ciocalteu method according Tian et al. (29 (link)), with slight modifications. Extract solution (100 μL) was mixed with 7.9 mL of distilled water and 500 μL of Folin-Ciocalteu reagent, then after 5 min, 1.5 mL of sodium carbonate solution (20%, w/v) was added. After resting for 2 h at room temperature, in the dark, the absorbance at 765 nm was measured using a spectrophotometer (UV-1780, Suzhou Shimadzu Instrument Co., Ltd., Suzhou, Jiangsu, China). The result was expressed as mg of gallic acid (GA) equivalent in 1 g dry weight of sample (mg GA eq/g DW).