Antioxidant Activities of Sicilian Prickly Pear (Opuntia ficus indica) Fruit Extracts and Reducing Properties of Its Betalains: Betanin and Indicaxanthin

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• 作者：Daniela Butera ; Luisa Tesoriere ; Francesca Di Gaudio ; Antonino Bongiorno ; Mario Allegra ; Anna Maria Pintaudi ; Rohn Kohen ; and Maria A. Livrea
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2002
• 出版时间：November 6, 2002
• 年：2002
• 卷：50
• 期：23
• 页码：6895 - 6901
• 全文大小：113K
• 年卷期：v.50,no.23(November 6, 2002)
• ISSN：1520-5118

文摘

Sicilian cultivars of prickly pear (Opuntia ficus indica) produce yellow, red, and white fruits, due tothe combination of two betalain pigments, the purple-red betanin and the yellow-orange indicaxanthin.The betalain distribution in the three cultivars and the antioxidant activities of methanolic extractsfrom edible pulp were investigated. In addition, the reducing capacity of purified betanin andindicaxanthin was measured. According to a spectrophotometric analysis, the yellow cultivar exhibitedthe highest amount of betalains, followed by the red and white ones. Indicaxanthin accounted forabout 99% of betalains in the white fruit, while the ratio of betanin to indicaxanthin varied from 1:8(w:w) in the yellow fruit to 2:1 (w:w) in the red one. Polyphenol pigments were negligible componentsonly in the red fruit. When measured as 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid(Trolox) equivalents per gram of pulp, the methanolic fruit extracts showed a marked antioxidantactivity. Vitamin C did not account for more than 40% of the measured activity. In addition, the extractsdose-dependently inhibited the organic hydroperoxide-stimulated red cell membrane lipid oxidation,as well as the metal-dependent and -independent low-density lipoprotein oxidation. The extract fromthe white fruit showed the highest protection in all models of lipid oxidation. Purified betanin andindicaxanthin were more effective than Trolox at scavenging the [2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)] diammonium salt cation radical. Cyclic voltammetric measurements show two anodicwaves for betanin and indicaxanthin, and differential pulse voltammetry shows three anodic wavesfor betanin, with calculated peak potentials of 404, 616, and 998 mV, and two anodic waves forindicaxanthin, with peak potentials of 611 and 895 mV. Betanin underwent complex formation throughchelation with Cu²⁺, whereas indicaxanthin was not modified. These findings suggest that the abovebetalains contribute to the antioxidant activity of prickly pear fruits.Keywords: Betalains; natural antioxidants; low-density lipoprotein; prickly pear; betanin; indicaxanthin