Division of Wildlife & Ecology, CSIRO, PO Box 84, 2601, Lyneham, ACT, Australia.
J Chem Ecol. 1991 Jan;17(1):123-34. doi: 10.1007/BF00994426.
Optimal conditions for extraction of tannins and other phenolics from tree foliage and their subsequent storage rarely have been investigated. We investigated methods of drying leaves, optimal solvents, and the effects of light and temperature on the extractability and stability of condensed tannins (proanthocyanidins) and total phenolics from leaves ofEucalyptus trees. Aqueous acetone was a better solvent than aqueous methanol for condensed tannins and total phenolics, but condensed tannins were less stable in aqueous acetone than aqueous methanol. Stability of condensed tannins also was decreased substantially by room temperature versus 4°C and by exposure to indirect sunlight, although the assay for total phenolics was unaffected. For quantitative estimation of condensed tannins, extraction with 50% acetone was better than methods of direct analysis of leaf tissue. The highest estimates of total condensed tannins were obtained by exhaustive extraction with 50% acetone followed by direct analysis of the residue. Lyophilization of fresh leaf increased yield of condensed tannin (although usually by less than 10%). Lyophilization and subsequent storage of extracts had little effect on assays for condensed tannins or total phenolics.
从树叶中提取单宁和其他酚类物质及其后续储存的最佳条件很少被研究过。我们研究了干燥叶片的方法、最佳溶剂，以及光照和温度对桉树叶片中缩合单宁（原花青素）和总酚类物质的提取率和稳定性的影响。与水甲醇相比，水丙酮是更好的溶剂，用于提取缩合单宁和总酚类物质，但缩合单宁在水丙酮中的稳定性不如水甲醇。与 4°C 相比，室温以及间接阳光暴露会大大降低缩合单宁的稳定性，尽管总酚类物质的测定不受影响。对于缩合单宁的定量估计，用 50%丙酮提取比直接分析叶片组织的方法更好。通过用 50%丙酮进行彻底提取，然后直接分析残留物，可以获得总缩合单宁的最高估计值。新鲜叶片的冻干会增加缩合单宁的产量（尽管通常不超过 10%）。冻干和随后的提取物储存对缩合单宁或总酚类物质的测定几乎没有影响。
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