Department of Analytical Chemistry, Faculty of Sciences, University of Granada, c/ Fuentenueva s/n, 18071 Granada, Spain.
Phytochem Anal. 2013 May-Jun;24(3):213-23. doi: 10.1002/pca.2401. Epub 2012 Sep 15.
Olea europaea L. leaves may be considered a cheap, easily available natural source of phenolic compounds. In a previous study we evaluated the possibility of obtaining bioactive phenolic compounds from olive leaves by pressurised liquid extraction (PLE) for their use as natural anti-oxidants. The alimentary use of these kinds of extract makes comprehensive knowledge of their composition essential.
To undertake a comprehensive characterisation of two olive-leaf extracts obtained by PLE using high-performance liquid chromatography coupled to electrospray ionisation and quadrupole time-of-flight mass spectrometry (HPLC-ESI-QTOF-MS).
Olive leaves were extracted by PLE using ethanol and water as extraction solvents at 150°C and 200°C respectively. Separation was carried out in a HPLC system equipped with a C₁₈-column working in a gradient elution programme coupled to ESI-QTOF-MS operating in negative ion mode.
This analytical platform was able to detect 48 compounds and tentatively identify 31 different phenolic compounds in these extracts, including secoiridoids, simple phenols, flavonoids, cinnamic-acid derivatives and benzoic acids. Lucidumoside C was also identified for the first time in olive leaves.
The coupling of HPLC-ESI-QTOF-MS led to the in-depth characterisation of the olive-leaf extracts on the basis of mass accuracy, true isotopic pattern and tandem mass spectrometry (MS/MS) spectra. We may conclude therefore that this analytical tool is very valuable in the study of phenolic compounds in plant matrices.
油橄榄叶可被视为一种廉价、易得的天然酚类化合物来源。在之前的研究中，我们评估了通过加压液体萃取（PLE）从橄榄叶中获得生物活性酚类化合物的可能性，将其用作天然抗氧化剂。这些提取物的食用用途需要全面了解其组成。
采用高效液相色谱-电喷雾离子化-四极杆飞行时间质谱联用（HPLC-ESI-QTOF-MS）对通过 PLE 获得的两种橄榄叶提取物进行全面表征。
使用乙醇和水作为提取溶剂，分别在 150°C 和 200°C 下通过 PLE 提取橄榄叶。在配备 C₁₈ 柱的 HPLC 系统中进行分离，采用梯度洗脱程序，与工作在负离子模式下的 ESI-QTOF-MS 联用。
该分析平台能够检测到 48 种化合物，并初步鉴定出这两种提取物中的 31 种不同的酚类化合物，包括环烯醚萜、简单酚类、类黄酮、肉桂酸衍生物和苯甲酸。灵芝酸 C 也首次在橄榄叶中被鉴定出来。
HPLC-ESI-QTOF-MS 的联用实现了基于质量精度、真实同位素模式和串联质谱（MS/MS）图谱对橄榄叶提取物的深入表征。因此，我们可以得出结论，这种分析工具在植物基质中酚类化合物的研究中非常有价值。
