Section of Organic Chemistry and Biochemistry, Department of Chemistry, University of Ioannina, Ioannina, Greece.
J Agric Food Chem. 2010 Mar 24;58(6):3303-8. doi: 10.1021/jf903823x.
The contribution of flavonoids to the overall radical scavenging activity of olive leaf polar extracts, known to be good sources of oleuropein related compounds, was examined. Off line and on line HPLC-DPPH(*) assays were employed, whereas flavonoid content was estimated colorimetrically. Individual flavonoid composition was first assessed by RP-HPLC coupled with diode array and fluorescence detectors and verified by LC-MS detection system. Olive leaf was found a robust source of flavonoids regardless sampling parameters (olive cultivar, leaf age or sampling date). Total flavonoids accounted for the 13-27% of the total radical scavenging activity assessed using the on line protocol. Luteolin 7-O-glucoside was one of the dominant scavengers (8-25%). Taking into consideration frequency of appearance the contribution of luteolin (3-13%) was considered important, too. Our findings support that olive leaf, except for oleuropein and related compounds, is also a stable source of bioactive flavonoids.
本研究考察了橄榄叶极性提取物（已知是橄榄苦苷相关化合物的良好来源）中类黄酮对其整体自由基清除活性的贡献。采用离线和在线 HPLC-DPPH(*)测定法，同时用比色法测定类黄酮含量。首先通过 RP-HPLC 与二极管阵列和荧光检测器联用评估了单个类黄酮的组成，并通过 LC-MS 检测系统进行了验证。无论采样参数（橄榄品种、叶片年龄或采样日期）如何，橄榄叶都是类黄酮的丰富来源。采用在线方案评估，总类黄酮占总自由基清除活性的 13-27%。芦丁 7-O-葡萄糖苷是主要的清除剂之一（8-25%）。考虑到出现的频率，芦丁（3-13%）的贡献也被认为是重要的。我们的研究结果表明，除了橄榄苦苷和相关化合物外，橄榄叶也是生物活性类黄酮的稳定来源。
