Al-Mamary Mohammed Ali
Department of Organic Chemistry, Faculty of Pharmacy, Sana'a University Sana'a, P.O.Box 13697, Yemen.
Malays J Nutr. 2002 Sep;8(2):179-89. Epub 2002 Sep 15.
Of late, more attention has been paid to the role of natural antioxidants, especially phenolic compounds, which may act both by reducing the content of toxic compounds in foods and by supplying the human body with exogenous antioxidants. The total phenolic contents and the total antioxidant activities (% AA) of 17 commonly consumed vegetables in Yemen were determined. Total phenolics was measured colorimetrically using the Folin-Ciocalteu reagent with D-catechin as the standard. The antioxidant activity (%AA) of vegetables using their juices at different levels (50μl, 100μl, 200μl) was assayed in vitro by the inhibition of liver homogenate oxidation mediated by FeSO4 / ascorbate system. The % AA was measured by the TBAR method. The results showed that for all vegetable juices, increased antioxidant activity or decreased prooxidant activity increased with volume of juice. With the addition of 50μl from each sample, most vegetable juices showed antioxidant activity and it appears that coriander had exceptionally high antioxidant activity (60%). However, garlic, yellow onion, parsley, red onion and Cissus rotundifolia showed considerably high antioxidant activities (54-41 %). Other vegetables with low antioxidant activities (27 to 3 %) showed an order of increase in %AA as follows: tomato > spinach > horseradish-leaves > carrot > cabbage > chilli > leek > horseradish-roots. At the same, time some vegetable juices such as that of green pepper, cucumber and lettuce showed initial prooxidant activities (-11 to -40 %). The complete inhibition of oxidation was noticed when the highest level of juices (200μl) was used in the cases of coriander, onions, garlic and parsley. The correlation between total phenolics and the antioxidant activities of vegetables with different levels of juices (50μl, 100μl and 200μl) showed positive but not significant correlations (R = 0.41 - 0.55). Some vegetables such as carrots and tomatoes show the highest relative antioxidant efficiencies despite the small content of total phenolics compared to other vegetables tested in this study.
近来，人们越来越关注天然抗氧化剂的作用，尤其是酚类化合物，它们可能通过减少食物中有毒化合物的含量以及为人体提供外源性抗氧化剂来发挥作用。测定了也门17种常见食用蔬菜的总酚含量和总抗氧化活性（%AA）。总酚含量采用Folin-Ciocalteu试剂比色法测定，以D-儿茶素为标准品。通过抑制FeSO4/抗坏血酸系统介导的肝脏匀浆氧化，体外测定不同浓度（50μl、100μl、200μl）蔬菜汁的抗氧化活性（%AA）。%AA采用硫代巴比妥酸法测定。结果表明对于所有蔬菜汁，抗氧化活性增加或促氧化活性降低都随蔬菜汁体积增加。加入每个样品50μl时，大多数蔬菜汁表现出抗氧化活性，香菜似乎具有极高的抗氧化活性（60%）。然而，大蒜、黄洋葱、欧芹、红洋葱和圆叶白粉藤表现出相当高的抗氧化活性（54 - 41%）。其他抗氧化活性较低（27%至3%）的蔬菜，其%AA增加顺序如下：番茄＞菠菜＞辣木叶＞胡萝卜＞卷心菜＞辣椒＞韭菜＞辣根。同时，一些蔬菜汁如青椒、黄瓜和生菜汁表现出初始促氧化活性（-11至-40%）。在香菜、洋葱、大蒜和欧芹的情况下，使用最高浓度的蔬菜汁（200μl）时可观察到氧化完全被抑制。不同浓度（50μl、100μl和200μl）蔬菜汁的总酚含量与抗氧化活性之间的相关性呈正相关但不显著（R = 0.41 - 0.55）。与本研究中测试的其他蔬菜相比，一些蔬菜如胡萝卜和番茄尽管总酚含量较低，但表现出最高的相对抗氧化效率。
