Station d'Amélioration des Arbres Forestiers, Institut National de la Recherche Agronomique, Ardon, F-45160, Olivet, France.
J Chem Ecol. 1991 May;17(5):887-96. doi: 10.1007/BF01395597.
The radial diffusion assay was applied to estimate the amount of total tannins in extracts from walnut plant materials. We found that the protein-precipitating activity of the tannin extracts were increased by 30-75 % when antioxidants (ascorbic acid or sodium metabisulfite, 5.5 mM) were added in extraction solvents (50% aqueous methanol). The extracts obtained with Na2S2O5 were much less brown than control. Moreover, two-dimensional thin-layer chromatography revealed some additional polyphenolic compounds in the extracts made with Na2S2O5. These results suggest that the amount of tannins and/or their protein-precipitating property may be strongly affected by oxidation events during extraction procedure. The addition of antioxidants in the extraction solvents is useful to limit this problem.
径向扩散法被用于估计从核桃植物材料提取物中的总单宁含量。我们发现，当在提取溶剂（50%甲醇水溶液）中加入抗氧化剂（抗坏血酸或亚硫酸氢钠，5.5mM）时，单宁提取物的蛋白质沉淀活性增加了 30-75%。用 Na2S2O5 提取的提取物比对照物的颜色浅得多。此外，二维薄层层析显示，用 Na2S2O5 提取的提取物中还有一些额外的多酚化合物。这些结果表明，单宁的含量和/或其蛋白质沉淀特性可能会受到提取过程中氧化事件的强烈影响。在提取溶剂中加入抗氧化剂有助于解决这个问题。
