De Leonardis Antonella, Macciola Vincenzo, Cuomo Francesca, Lopez Francesco
Department of Agricultural, Environmental and Food Sciences (DIAAA), University of Molise, Via De Sanctis, I-86100 Campobasso, Italy.
Department of Agricultural, Environmental and Food Sciences (DIAAA), University of Molise, Via De Sanctis, I-86100 Campobasso, Italy.
Food Chem. 2015 May 15;175:568-74. doi: 10.1016/j.foodchem.2014.12.016. Epub 2014 Dec 13.
The enzymatic activity of raw protein olive leaf extract has been investigated in vivo, on olive leaf homogenate and, in vitro with pure oleuropein and other phenolic substrates. At least two types of enzymes were found to be involved in the degradation of endogenous oleuropein in olive leaves. As for the in vitro experiments, the presence of active polyphenoloxidase and β-glucosidase was determined by HPLC and UV-Visible spectroscopy. Interestingly, both the enzymatic activities were found to change during the storage of olive leaves. Specifically, the protein extracts obtained from fresh leaves showed the presence of both the enzymatic activities, because oleuropein depletion occurred simultaneously with the formation of the oleuropein aglycon, 3,4-DHPEA-EA. In comparison leaves subjected to the drying process showed a polyphenoloxidase activity leading exclusively to the formation of oxidation products responsible for the typical brown coloration of the reaction solution.
已在体内、对橄榄叶匀浆以及在体外使用纯橄榄苦苷和其他酚类底物研究了未加工的蛋白质橄榄叶提取物的酶活性。发现至少有两种类型的酶参与橄榄叶中内源性橄榄苦苷的降解。至于体外实验，通过高效液相色谱法和紫外可见光谱法测定了活性多酚氧化酶和β-葡萄糖苷酶的存在。有趣的是，发现这两种酶活性在橄榄叶储存期间会发生变化。具体而言，从新鲜叶子中获得的蛋白质提取物显示出两种酶活性的存在，因为橄榄苦苷的消耗与橄榄苦苷苷元3,4-二羟基苯乙醇-对羟基苯乙酸酯的形成同时发生。相比之下，经过干燥处理的叶子表现出多酚氧化酶活性，仅导致形成负责反应溶液典型棕色的氧化产物。
