Department of Renewable Resources, University of Alberta, 442 Earth Sciences Building, Edmonton, AB T6G2E3, Canada.
J Chem Ecol. 2011 Mar;37(3):311-9. doi: 10.1007/s10886-011-9921-8. Epub 2011 Feb 22.
We examined how tannin structure influences reactivity in tannin assays and carbon and nitrogen mineralization. Condensed tannins from the foliage of ten tree and shrub species and from pecan shells (Carya illinoensis) had different proportions of: (a) epicatechin (cis) and catechin (trans) isomers, (b) procyanidin (PC) and prodelphinidin (PD) monomers, and (c) different chain lengths. The response of each tannin to several widely used tannin assays was determined. Although there was some variation in response to proanthocyanidin (butanol/HCl) and Folin Ciocalteu assays, we did not deduce any predictable relationship between tannin structure and response to either assay. There was little variation in protein precipitation among the different tannins. To assess biological activity, six of the tannins were incubated with forest humus for 22 days. We determined that, while PC-based tannins remained at least partly extractable for the duration of the incubation, tannins with a high proportion of PD subunits rapidly became unextractable from soil. There was a positive correlation between net nitrogen mineralization and cis chemical structure. Carbon mineralization was enhanced initially by the addition of tannins to humus, but after 22 days, a negative correlation between the proportion of cis subunits and respiration was determined. Overall, we were not able to demonstrate consistent effects of structure on either microbial mineralization or reactivity to chemical assays; such relationships remain elusive.
我们研究了单宁结构如何影响单宁测定和碳氮矿化中的反应性。来自十种树木和灌木的叶以及山核桃壳（Carya illinoensis）的缩合单宁具有不同比例的：（a）表儿茶素（顺式）和儿茶素（反式）异构体，（b）原花青素（PC）和原矢车菊素（PD）单体，以及（c）不同的链长。每种单宁对几种广泛使用的单宁测定的反应都进行了测定。尽管在对原花青素（正丁醇/ HCl）和福林-希科莱特测定的反应中存在一些差异，但我们无法推断出单宁结构与任何一种测定的反应之间存在任何可预测的关系。不同单宁之间的蛋白质沉淀差异不大。为了评估生物活性，将其中六种单宁与森林腐殖质孵育 22 天。我们发现，虽然基于 PC 的单宁在孵育期间至少部分可提取，但 PD 亚基比例较高的单宁会迅速从土壤中变得不可提取。净氮矿化与顺式化学结构之间存在正相关。添加单宁最初会促进腐殖质中的碳矿化，但 22 天后，确定顺式亚基与呼吸之间呈负相关。总的来说，我们无法证明结构对微生物矿化或对化学测定的反应性的一致影响；这种关系仍然难以捉摸。
