Lindroth R L, Pajutee M S
Department of Entomology, University of Wisconsin, 1630 Linden Drive, 53706, Madison, WI, USA.
Oecologia. 1987 Nov;74(1):144-148. doi: 10.1007/BF00377359.
Phenolic glycosides have been the subject of considerable interest in recent ecological and systematic studies, especially those involving the Salicaceae. But these compounds are markedly labile in aqueous media, and the consequences of spontaneous degradation for valid interpretation of results have been largely ignored by researchers. We found that freeze-drying and oven-drying of leaf samples from several Populus and Salix species produced dramatic changes in the total and relative concentrations of specific phenolic glycosides, when compared to analyses of fresh material. Extraction in aqueous and alcoholic media for extended (24 h) periods also effected changes in glycoside concentrations. Alterations in phenolic glycoside concentrations, interconversions among glycosides, and production of artifactual glycosides result from a series of hydrolytic reactions. These deleterious effects can be best (but not entirely) avoided by the use of fresh plant material, cold, nonaqueous extraction solvents, and short extraction times. Because individual phenolic glycosides exhibit very different biological activities against herbivores, we caution ecologists to use utmost care in the performance and interpretation of phenolic glycoside assays.
酚苷在最近的生态学和系统学研究中备受关注，尤其是在涉及杨柳科植物的研究中。但这些化合物在水性介质中极不稳定，而研究人员在很大程度上忽略了自发降解对结果合理解释的影响。我们发现，与新鲜材料分析相比，对几种杨树和柳树叶片样本进行冷冻干燥和烘干会使特定酚苷的总量和相对浓度发生显著变化。在水性和醇性介质中长时间（24小时）提取也会导致糖苷浓度的变化。酚苷浓度的改变、糖苷之间的相互转化以及人工糖苷的产生是由一系列水解反应引起的。通过使用新鲜植物材料、低温、非水性提取溶剂和短提取时间，可以最好地（但不能完全）避免这些有害影响。由于单个酚苷对食草动物表现出非常不同的生物活性，我们提醒生态学家在进行酚苷测定及其结果解释时要格外小心。
