Discipline of Nutrition, Faculty of Medical & Health Science, The University of Auckland, Private Bag 92019, Auckland, New Zealand.
Int J Mol Sci. 2009 Mar;10(3):1081-1103. doi: 10.3390/ijms10031081. Epub 2009 Mar 11.
DNA damage by reactive species is associated with susceptibility to chronic human degenerative disorders. Anthocyanins are naturally occurring antioxidants, that may prevent or reverse such damage. There is considerable interest in anthocyanic food plants as good dietary sources, with the potential for reducing susceptibility to chronic disease. While structure-activity relationships have provided guidelines on molecular structure in relation to free hydroxyl-radical scavenging, this may not cover the situation in food plants where the anthocyanins are part of a complex mixture, and may be part of complex structures, including anthocyanic vacuolar inclusions (AVIs). Additionally, new analytical methods have revealed new structures in previously-studied materials. We have compared the antioxidant activities of extracts from six anthocyanin-rich edible plants (red cabbage, red lettuce, blueberries, pansies, purple sweetpotato skin, purple sweetpotato flesh and Maori potato flesh) using three chemical assays (DPPH, TRAP and ORAC), and the in vitro Comet assay. Extracts from the flowering plant, lisianthus, were used for comparison. The extracts showed differential effects in the chemical assays, suggesting that closely related structures have different affinities to scavenge different reactive species. Integration of anthocyanins to an AVI led to more sustained radical scavenging activity as compared with the free anthocyanin. All but the red lettuce extract could reduce endogenous DNA damage in HT-29 colon cancer cells. However, while extracts from purple sweetpotato skin and flesh, Maori potato and pansies, protected cells against subsequent challenge by hydrogen peroxide at 0 degrees C, red cabbage extracts were pro-oxidant, while other extracts had no effect. When the peroxide challenge was at 37 degrees C, all of the extracts appeared pro-oxidant. Maori potato extract, consistently the weakest antioxidant in all the chemical assays, was more effective in the Comet assays. These results highlight the dangers of generalising to potential health benefits, based solely on identification of high anthocyanic content in plants, results of a single antioxidant assay and traditional approaches to structure activity relationships. Subsequent studies might usefully consider complex mixtures and a battery of assays.
活性物质对 DNA 的损伤与慢性人类退行性疾病的易感性有关。花色苷是天然存在的抗氧化剂，可能预防或逆转这种损伤。花色苷类植物作为良好的饮食来源，具有降低慢性疾病易感性的潜力，因此受到了相当大的关注。虽然结构-活性关系为与游离羟自由基清除相关的分子结构提供了指导，但这可能无法涵盖食品植物中的情况，在食品植物中，花色苷是复杂混合物的一部分，并且可能是复杂结构的一部分，包括花色苷液泡内含物 (AVIs)。此外，新的分析方法揭示了以前研究材料中的新结构。我们使用三种化学测定法（DPPH、TRAP 和 ORAC）和体外彗星测定法比较了六种富含花色苷的可食用植物（红甘蓝、红生菜、蓝莓、三色堇、紫薯皮、紫薯肉和毛利土豆肉）提取物的抗氧化活性，并将百合提取物用作比较。提取物在化学测定中表现出不同的效果，表明密切相关的结构对不同的活性物质具有不同的亲和力。与游离花色苷相比，花色苷与 AVI 的整合导致更持续的自由基清除活性。除了红生菜提取物外，其他所有提取物都可以减少 HT-29 结肠癌细胞中的内源性 DNA 损伤。然而，虽然紫薯皮和肉、毛利土豆和三色堇的提取物可以保护细胞免受 0 摄氏度下过氧化氢的后续攻击，但红甘蓝提取物具有促氧化作用，而其他提取物则没有影响。当过氧化氢的挑战在 37 摄氏度时，所有的提取物都表现出促氧化作用。毛利土豆提取物在所有化学测定中始终是抗氧化能力最弱的，在彗星测定中效果更好。这些结果强调了仅基于植物中高花色苷含量的鉴定、单一抗氧化测定的结果和传统的结构活性关系方法，将其推广到潜在的健康益处存在的危险。随后的研究可能会有用地考虑复杂混合物和一系列测定。
