Selective Adsoprtion of Oleuropein from Olive (<i>Olea europaea</i>) Leaf Extract by Using Macroporous Resin

Extraction, optimization and adsorption of oleuropein from olive (<i>Olea europaea</i>) leaves were carried out, subsequently. Face centered composite design (FCCD) model was chosen for designing the experimental conditions for extraction of olive leaves through response surface methodology (RSM). Olive leaf extract obtained under the optimum conditions was concentrated by several macroporous resins (Amberlites XAD 2, XAD 4, XAD 7HP and XAD 16). The crude and purified extracts were evaluated according to their total phenolic material (TPM) and oleuropein concentration. XAD 7HP showed the best performance regarding adsorption (91%) and desorption ratio (97%) for oleuropein. Pseudo-first and second-order and Elovich kinetic models were efficient to represent the experimental data for the adsorption of TPM and oleuropein with high correlation coefficients. Equilibrium data were fitted to Langmuir and Freundlich isotherms at four different temperature values. The antioxidant capacity of the extracts was evaluated with several assays such as CUPRAC, DPPH and ABTS.本研究依次开展了油橄榄（Olea europaea）叶片中橄榄苦苷的提取、优化与吸附实验。采用响应面法（Response Surface Methodology, RSM），选取中心复合设计（Face Centered Composite Design, FCCD）模型优化油橄榄叶片提取的实验参数。将最优条件下制备的油橄榄叶片提取物，通过Amberlites XAD 2、XAD 4、XAD 7HP及XAD 16等多种大孔吸附树脂进行浓缩纯化。分别以总酚类物质（Total Phenolic Material, TPM）含量与橄榄苦苷浓度为评价指标，对粗提取物与纯化提取物进行检测分析。其中XAD 7HP对橄榄苦苷的吸附率达91%、解吸率达97%，综合性能最优。准一级、准二级动力学模型与Elovich动力学模型均可较好拟合总酚类物质与橄榄苦苷的吸附实验数据，且拟合相关系数较高。在四种不同温度条件下获取的平衡吸附数据，分别采用朗缪尔（Langmuir）与弗伦德里希（Freundlich）等温吸附模型进行拟合。采用CUPRAC、DPPH及ABTS等多种抗氧化活性检测方法，对提取物的抗氧化能力进行了评价。