Ultrasonic-assisted extraction flavonoids and ability to scavenge 1,1-diphenyl 2-picrylhydrazyl (DPPH) radicals from medlar (a Miller) leaves and fruits

摘要

The extraction technique of flavonoids from the tender leaves and fruits of medlar (Lycium chinense?Miller) were investigated, and?ability to scavenge 1,1-diphenyl 2-picrylhydrazyl (DPPH) radicals of both?was?compared. Through single-factor and the L9?(34) orthogonaldesign, the optimal extraction parameters were determined. The results showed that the flavonoids content was?significantly higher in the leaves than in the fruits. There were?four important factors influencing the yields of flavonoids, including?ethanol concentration, extraction time, solid-liquid ratio and extraction temperature. As for leaves, the optimum extraction parameters were 80%?ethanol?content, solid-liquid ratio 1:50, extract times?2times per 40 min,?and?60°C.?While for?fruits, the optimum parameters?were?80%?ethanol content, 1:50 solid-liquid?ratio,?2?per 30 min and 60°C. Under the optimum condition, the yield of flavonoids from leaves and fruits?are?47.371 and 9.593 mg.g-1, respectively.?Theflavonoids?in leaves and fruits have good capability to scavenge the DPPH radicals, and the scavenging capability is obviously related to the concentrations.