Ellagitannins have Greater Oxidative Activities than Condensed Tannins and Galloyl Glucoses at High pH: Potential Impact on Caterpillars

摘要: Plants synthesize a diversity of tannin structures but little is known about whether these different types have oxidative activities in herbivores. Oxidative hydrolyzable and condensed tannins were compared at pH 10 with two methods: EPR spectrometry was used to quantify semiquinone radicals anoxic conditions spectrophotometric assay measure the rate browning phenolics oxidized ambient oxygen conditions. A little-studied group (ellagitannins) contained most active examined, forming high concentrations highest rates. On average, galloyl glucoses high-molecular-weight gallotannins had intermediate low activities. Condensed generally formed levels browned slowly. The results suggest that ellagitannin-rich plants defenses against herbivores, such as caterpillars, whereas opposite may hold true for contain predominantly or gallotannins.