Department of Bioengineering, Faculty of Food Science and Engineering, Dunarea de Jos University, Galati, Romania.
J Chromatogr A. 2011 Jul 29;1218(30):4918-27. doi: 10.1016/j.chroma.2010.11.055. Epub 2010 Nov 27.
In this contribution, pressurized liquid extraction (PLE) has been employed to isolate bioactive compounds from three native Romanian plants, oregano (Origanum vulgare), tarragon (Artemisia dracunculus) and wild thyme (Thymus serpyllum). Different PLE conditions have been tested including extraction with water, ethanol and their mixtures in a wide range of extraction temperatures (50-200°C), and the antioxidant capacity of the extracts was measured using different assays (DPPH radical scavenging, TEAC assay and Folin-Ciocalteau assay to measure total phenols). Moreover, a complete chemical characterization by using LC-MS/MS was carried out to be able to correlate the bioactivity with the particular chemical composition of each extract and plant. The use of PLE with water as a solvent at the highest temperature tested (200°C) always provided the highest extraction yields for the three studied plants, being maximum for oregano (>60%). Besides, oregano's pressurized water extracts at lower temperatures (50°C) presented the highest content on total phenols (184.9 mg gallic acid/g extract) and the best antioxidant activities (EC(50) 6.98 μg/ml). In general, oregano extracts were the most active, followed by wild thyme extracts. The antioxidant capacity measured by DPPH assay was highly correlated with the amount of total phenols. Moreover, the use of a LC-MS/MS method allowed the identification of 30 different phenolic compounds in the different extracts, including phenolic acids, flavones, flavanones and flavonols, which have an important influence on the total antioxidant capacity of the different extracts.
在本研究中，采用加压液体萃取（PLE）从三种罗马尼亚本地植物（牛至（Origanum vulgare）、龙蒿（Artemisia dracunculus）和野生百里香（Thymus serpyllum））中分离生物活性化合物。测试了不同的 PLE 条件，包括用水、乙醇及其混合物在较宽的提取温度范围（50-200°C）下进行提取，并使用不同的测定法（DPPH 自由基清除、TEAC 测定法和 Folin-Ciocalteau 测定法测定总酚）来测量提取物的抗氧化能力。此外，通过使用 LC-MS/MS 进行了全面的化学表征，以能够将生物活性与每个提取物和植物的特定化学成分相关联。使用水作为溶剂，在测试的最高温度（200°C）下进行 PLE，总是为三种研究植物提供最高的提取产率，牛至的产率最高（>60%）。此外，牛至的加压水提取物在较低温度（50°C）下表现出最高的总酚含量（184.9 mg 没食子酸/g 提取物）和最佳的抗氧化活性（EC（50）6.98 μg/ml）。一般来说，牛至提取物最活跃，其次是野生百里香提取物。DPPH 测定法测量的抗氧化能力与总酚含量高度相关。此外，使用 LC-MS/MS 方法可以在不同提取物中鉴定出 30 种不同的酚类化合物，包括酚酸、黄酮、黄烷酮和黄酮醇，它们对不同提取物的总抗氧化能力有重要影响。
