Extraction of total phenolic compounds from yellow poplar hydrolysate and evaluation of their antioxidant activities

Total phenolic compounds (TPC) from yellow poplar hydrolysate were extracted and their antioxidant activity was investigated. Of the different methods used for TPC extraction from the hydrolysate, solvent extraction was most effective having an efficiency of 84.84%. Based on adsorption and desorption of TPC on different materials, XAD resin showed high efficiency for adsorption and desorption in the range from 80.38 to 94.20% and from 75.14 to 82.10%, respectively. However, activated carbon was effective for adsorption of TPC, but the desorption efficiency was low, ranging from 0.55 to 3.31%, depending on the solvent. Among the resin types, XAD-16 was more effective in adsorption compared to XAD-4. All the extracts contained mainly sugar- and lignin-derived compounds, including xylose, acetic acid, and benzaldehyde. Antioxidant activity of the extract was determined using DPPH, ABTS, and reducing power. Solvent and pump XAD-16 resin extract showed excellent antioxidant activity comparable with that of the positive control. Strong significant correlations between TPC and antioxidant activities were observed at p-value of 0.001.