Study On Extraction, Purification And Antioxidant Activities Of Total Flavonoids From Peanut Shell

In this paper, the extraction, purification of total flavonoids from peanut hulls by ethanol solution assisted with microwave method, metal ions chelating technology and macroporous resins methods were studied. The free radical (DPPH·and·H) scavenging activities of the ex-purified flavonoids, the metal-flavonoids complex and purified total flavonoids from peanut hulls were investigated by the methods of DPPH·and salicylic acid-ferrous sulfate. The main conclusions were as follows:1. The total flavonoids were extracted from peanut hulls by ethanol solution assisted with microwave. The optimum processing conditions were as follows:the mass ratio of solvent and solid was 25:1, the solvent was 60%, the microwave treating power was 528W, the peanut hulls were extracted 4min for two times. Under the optimum condition, the yield of flavonoids was 1.77% and the content of the Luteolin was 3.78%.2. Based on the chelation between flavonoids and metal ions, a new process for purifying flavonoids from peanut shell using Ca2+ was developed for the first time. The results indicated the optimal purification conditions:the pH of flavonoids extracts solution was 9.0, calcium chloride and flavonoids extracts ratio (w/w) was 1:10 and initial concentration of flavonoids extracts was 10.0 mg/mL. Under the optimum condition, the content of flavonoids was up to 27.84% from 11.0%. The Luteolin content increased to 1.97% from 0.87%. The free radical scavenging activities were studied and the results showed that the purified flavonoids showed strong antioxidant activities, and both·OH and DPPH·free radicals scavenging activity were stronger than that of ex-purified flavonoids and the metal-chelating complex. The maximum scavenging rates were 90.56% and 96.21%.3. Based on the batch adsorption experiments with D101, the purification of total flavonoids from peanut hulls was studied and found that the optimal purification conditions for adsorption were adsorption time 3h, sample solution pH 4, adsorption temperature 25℃, and for desorption were desorption time 3h, elution solvent ethanol-water (80:20, V/V), the pH of sample solution 5, desorption temperature 30℃. Under the optimum condition, the content of flavonoids was up to 20.24% from 11.0%. The Luteolin content increased to 1.48% from 0.72%. The content of total flavonoids of peanut shell and Luteolin purified by Ca2+ chelating technology firstly and then purified by D101 were 37.47% and 2.74% respectively.