Optimizing the extraction of phenolic antioxidants from kudingcha made frrom Ilex kudingcha C.J. Tseng by using response surface methodology

Kudingcha made from Ilex kudingcha C.J. Tseng is a potent antioxidant in vitro and rich in polyphenolic compounds. For better utilization of the resource, response surface methodology was used to optimize the extraction conditions of polyphenolic antioxidants from kudingcha. In the present study, the total polyphenol content (TPC) and IC50 of scavenging activity on 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical were considered as the response values. Through optimization, the optimal extraction conditions with ethanol as extraction solvent were as follows: ethanol concentration 71%, extraction temperature 74 °C and time 61 min for TPC (235.24 mg chlorogenic acid/g); ethanol concentration 70%, extraction temperature 71 °C and time 60 min for potent scavenging activity on DPPH free radical (IC50 480.87 μg/mL). While for water as a solvent, the optimal conditions were extraction temperature 91 V and time 36 min for TPC (198.45 mg chlorogenic acid/g) and extraction temperature 92 °C and time 36 min for potent DPPH free radical scavenging activity (744.74 μg/mL). Similar parameters were obtained for extraction with higher TPC and lower IC50 of scavenging activity on DPPH free radical when using either ethanol or water as solvent. Our results suggest that the same optimal conditions can be used to get extract of kudingcha with higher TPC and lower IC50 of scavenging activity on DPPH free radical with ethanol or water as solvent.

► Response surface methodology was used to determine the extraction parameters for kudingcha extract with higher total polyphenol content (TPC) and lower IC50 value of scavenging activity on 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical.
► Optimal extraction conditions with ethanol solution as extraction solvent were ethanol concentration 72%, extraction temperature 68 °C and time 59 min.
► Optimal extraction conditions with water as extraction solvent were extraction temperature 91 °C and time 32 min.
► The regression models obtained were accurate and adequate for the extraction of polyphenol antioxidants from kudingcha with ethanol solution or water as extraction solvent.