Emam A M, Mohamed M A, Diab Y M, Megally N Y
Biochemistry Department, Faculty of Agriculture, Fayoum University, Egypt.
Drug Discov Ther. 2010 Jun;4(3):202-7.
In recent years, there has been increasing interest in finding naturally occurring antioxidants from plants for use in food and medicinal materials to replace synthetic antioxidants since such antioxidants are being restricted due to their side effects like carcinogenicity. The aim of this work was to examine the in vitro antioxidant activity of Laurus nobilis and Emex spinosus leaves and to isolate and structurally elucidate the active compounds in those leaves. The aqueous ethanolic extracts (70%) of Laurus nobilis and Emex spinosus leaves exhibited free radical scavenging action against 1,1-diphenyl-2-picrylhydrazyl (DPPH). Their concentrations of 50% inhibition (IC(50)) were 25.3 and 20.73 μg/mL, respectively. Activity-guided separation of these extracts using a combination of different chromatographic methods (TLC and column chromatography) resulted in the isolation of five chromatographically pure compounds (three from Laurus nobilis and two from Emex spinosus leaves). Spectroscopic methods ((1)H, (13)C-NMR, UV and MS) and chemical methods (detection tests and acidic hydrolysis) revealed the isolated antioxidant compounds to be flavonoid substances that were identified as kaempferol, kaempferol-3-rhamnopyranoside, and kaempferol-3,7-dirhamnopyranoside from Laurus nobilis extract and luteolin and rutin from Emex spinosus extract. The five flavonoids had varying ability to inhibit DPPH radicals (IC(50) from 4 to 35.8 μg/mL). Luteolin and rutin had strong scavenging action with an IC(50) of 4 and 4.6 μg/mL, respectively, and this action was stronger than that of synthetic antioxidant BHA, i.e., butylated hydroxyanisole (IC50 = 5.6 μg/mL).
近年来，人们越来越有兴趣从植物中寻找天然存在的抗氧化剂，用于食品和医药材料，以取代合成抗氧化剂，因为这类抗氧化剂因其致癌性等副作用而受到限制。这项工作的目的是研究月桂叶和刺藜叶的体外抗氧化活性，并分离和鉴定这些叶子中的活性化合物。月桂叶和刺藜叶的乙醇水提取物（70%）对1,1-二苯基-2-苦基肼（DPPH）表现出自由基清除作用。它们的50%抑制浓度（IC50）分别为25.3和20.73μg/mL。使用不同色谱方法（薄层色谱和柱色谱）的组合对这些提取物进行活性导向分离，得到了五种色谱纯化合物（三种来自月桂叶，两种来自刺藜叶）。光谱方法（1H、13C-NMR、UV和MS）和化学方法（检测试验和酸性水解）表明，分离出的抗氧化化合物是黄酮类物质，从月桂叶提取物中鉴定为山奈酚、山奈酚-3-鼠李糖苷和山奈酚-3,7-二鼠李糖苷，从刺藜叶提取物中鉴定为木犀草素和芦丁。这五种黄酮类化合物对DPPH自由基的抑制能力各不相同（IC50为4至35.8μg/mL）。木犀草素和芦丁具有较强的清除作用，IC50分别为4和4.6μg/mL，且这种作用比合成抗氧化剂丁基羟基茴香醚（BHA，IC50 = 5.6μg/mL）更强。
