Determination of ascorbic acid and a-tocopherol in selected edible plants and their relationship to antioxidant activity / Siti Rohani Kamiran

Antioxidant are compounds that found to delay and inhibit the formation of a free radicals, thus giving protection from all kinds of disease. Earlier studies had proven that antioxidant activities were high in vegetables and fruits. This experimental study was conducted to determine ascorbic acid, a - tocopherol hi selected edible plants and then* relationship to antioxidant activity. The concentration of ascorbic acid determined using 2, titration method in tapioca shoots, cekur manis, selom, kesom, pudina and ulam raja were 192.89, 10.2.00, 68.33, 45.87, 31.67, and 15.60mg/100g, respectively. Alpha - tocopherol content of all samples were determined using Hexane- ethyl- acetate extraction. The concentration of a - tocopherol in cekur manis, selom and ulam raja were 19.23, 10.16 and 7.12mg/100g, respectively. Only trace amount of a - tocopherol found in other samples. Sample were extracted using 80% methanol solution for antioxidant activity determination using p - carotene bleaching method. The sequence of the antioxidant activity in these plants were as follows: kesom, pudina, tapioca shoots, selom, cekur manis and ulam raja. The total antioxidant activity of these plants were compared to a - tocopherol and BHT as standard. This study indicates that the presence of only ascorbic acid or a - tocopherol in that particular plant does not contribute much to its antioxidant activity. The presence of other antioxidant compound like polyphenol or the combination of a few antioxidant compounds in that plant responsible for its high antioxidant activity.