Ellagitannins have greater oxidative activities than condensed tannins and galloyl glucoses at high pH: Potential impact on caterpillars
Ellagitannins have greater oxidative activities than condensed tannins and galloyl glucoses at high pH: Potential impact on caterpillars
复制标题
DOI：
10.1007/s10886-006-9143-7
复制
发表时间：
2006-10-01
影响因子：
2.3
通讯作者：
Salminen, Juha-Pekka
中科院分区：
文献类型：
--
作者：
Barbehenn, Raymond V.;Jones, Christopher P.;Salminen, Juha-Pekka
植物合成多种单宁结构，但对这些不同类型的单宁在食草动物中是否具有不同的氧化活性知之甚少。在pH值为10的条件下，通过两种方法比较水解单宁和缩合单宁的氧化活性：用EPR光谱法定量缺氧条件下的半醌自由基，用分光光度法测定环境氧条件下氧化的酚类物质的褐变速率。一组很少被研究的可水解单宁（鞣花单宁）含有最活跃的单宁，形成高浓度的半醌自由基，并以最高的速度变褐。平均而言，没食子酰葡萄糖和高分子量没食子单宁具有中等至低的氧化活性。浓缩单宁通常形成低水平的半醌自由基，并且褐色变慢。研究结果表明，富含鞣花单宁的植物对食草动物（如毛毛虫）具有积极的氧化防御能力，而主要含有浓缩单宁或高分子量没食子单宁的植物则相反。
Plants synthesize a diversity of tannin structures but little is known about whether these different types have different oxidative activities in herbivores. Oxidative activities of hydrolyzable and condensed tannins were compared at pH 10 with two methods: EPR spectrometry was used to quantify semiquinone radicals in anoxic conditions and a spectrophotometric assay was used to measure the rate of browning of phenolics oxidized in ambient oxygen conditions. A little-studied group of hydrolyzable tannins (ellagitannins) contained the most active tannins examined, forming high concentrations of semiquinone radicals and browning at the highest rates. On average, galloyl glucoses and high-molecular-weight gallotannins had intermediate to low oxidative activities. Condensed tannins generally formed low levels of semiquinone radicals and browned most slowly. The results suggest that ellagitannin-rich plants have active oxidative defenses against herbivores, such as caterpillars, whereas the opposite may hold true for plants that contain predominantly condensed tannins or high-molecular-weight gallotannins.