The Extraction And Purification Of Luteolin From Peanut Shell

Peanut shell contains not only carbohydrates and crude fibre, but also a variety of flavonoids substances. Luteolin is a main flavonoid in the peanut shell, with antibacterial, antiinflammatory, antispasmodic, expectorant, antioxidant, antitumor and other pharmacological activities. As a cheap renewable resource, peanut shell has wide application prospects and marketable value in the fields of raw medicine and food material if we can extract and purification luteolin.In this paper enzyme pre-treatment reflux extraction joint method was used to extract luteolin in the peanut shell. The effect of the enzyme solution pH, hydrolysis temperature, hydrolysis time, cellulose volume on the yield of total luteolin from peanut shell were studied. The best conditions of extraction were concluded as follows: pH 5.4, enzyme temperature of 50℃, hydrolysis time of 1.5 h, cellulose volume of 0.10%. Under the optimal conditions, it can be included that the luteolin yield is 2.83 mg·g^-1. And the mass transfer kinetics of luteolin extraction was established on the basis of the Fick's Second Law during reflux extraction process. Experimental datas of luteolin extraction were fitted respectively, and calculated some kinetics function values, such as k,Ea,D and so on. Therefore, the modified model can provide the valuable theory foundation for the technical designing and operational condition of luteolin extraction optimization.By column chromatography separation technology, thermodynamics and dynamics of adsorption of luteolin from peanut shell on polyamide were studied. The equilibrium isotherms were obtained in a range of temperatures, and the equilibrium data in this study have been found to fit the Langmuir adsorption isotherm. Thermodynamics parameters depicted the exothermic nature of physical adsorption and the process is spontaneous and favorable. Heat of adsorption, Gibbs free energy, entropy of adsorption were calculated according to the relationship of the thermodynamic function. Experimental datas were described by the pseudo first-order mode1 and the pseudo second-order mode1. The later model was agreed wel1 on the adsorption of luteolin on polyamide. The dynamic adsorption capacity measured from breakthrough curve is 0.2817 mg·g^-1, the total transfer mass coefficient is 0.0570 s^-1, and the height of mass transfer zone is 28.40 cm. Compared to isocratic elution, the optimal mobile phase proportion is 75% ethanol during gradient elution, purification effect is better.Using luteolin as imprinted molecule, methacrylic acid as functional monomer, ethyleneglycol dimethacrylate as the crosslinking agent, azobis(isobutyronitrile) as initiator and acetone as porogen, under the method of bulk polymerization molecular imprinted polymer was prepared by molecule printing technology. Selectivity and adsorption performance of the polymer to luteolin were studied through the static adsorption experiment. The results showed that the molecular imprinted polymer exhibited high selectivity and good recognition ability to luteolin by special imprinted effect but the blank polymer didn't. By solid-phase extraction column packed with the molecular imprinted polymer, luteolin can be separated from mixed flavonoids. After 55% methanol solution, luteolin was eluted with methanol. Meanwhile the polymer was used to separate the luteolin from peanut shell. It was satisfied that its purity could be increased from 2.51% to 93.40%, and its recovery is about 92.84%.