Abstract The bark of the tree species Myrcia eximia DC., which occurs in secondary forests in the Brazilian Amazon, is described for the first time. The aim was to provide a broad knowledge of its composition, to add value, and to direct uses to the bark of this species based on its polyphenolic content and antioxidant capacity. The bark is formed by conducting phloem, nonconducting phloem, and rhytidome. In addition, dead phloem occurs between the periderms. The average chemical composition of the bark was 45.6% total extractives, 1.4% suberin, 1.7% ash, and 21.1% lignin. The ethanol-water extract had a high content of flavonoids and condensed tannins [300.8 and 877.3 mg catechin equivalents (CE) g−1 of the extract, respectively]. High-performance liquid chromatography (HPLC) was used to quantify the presence of rutin, quercetin, and gallic, ferulic, and o-coumaric acids. The bark extract showed strong 2,2-diphenyl-1-picrylhydrazyl hydrate (DPPH) free radical scavenging activity, which was superior to that of the commercial antioxidant butylated hydroxytoluene (BHT), with an IC50 of 85.2 μg mL−1. Based on these results, it is evident that the bark of M. eximia from the Brazilian Amazon rainforest is a new and potential natural source of phenolic compounds and antioxidants, and its extracts can be used in the food and pharmaceutical industry and in various condensed tannin-based products.

中文翻译：

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Myrcia eximia DC 树皮的表征和评估。来自亚马逊雨林的树木作为酚类化合物的来源

摘要 首次描述了产于巴西亚马逊次生林的树种 Myrcia eximia DC. 的树皮。目的是提供有关其组成的广泛知识，增加价值，并根据其多酚含量和抗氧化能力直接用于该物种的树皮。树皮由传导韧皮部、非传导韧皮部和纹状体形成。此外，死韧皮部发生在周皮之间。树皮的平均化学成分为总提取物 45.6%、木栓质 1.4%、灰分 1.7% 和木质素 21.1%。乙醇-水提取物含有高含量的类黄酮和缩合单宁 [提取物的儿茶素当量 (CE) g-1 分别为 300.8 和 877.3 毫克]。使用高效液相色谱 (HPLC) 来量化芦丁、槲皮素和没食子的存在，阿魏酸和邻香豆酸。树皮提取物显示出强的 2,2-二苯基-1-苦基肼水合物 (DPPH) 自由基清除活性，优于商业抗氧化剂丁基化羟基甲苯 (BHT)，IC50 为 85.2 μg mL-1。基于这些结果，很明显，来自巴西亚马逊雨林的 M. eximia 树皮是酚类化合物和抗氧化剂的新的潜在天然来源，其提取物可用于食品和制药行业以及各种缩合单宁基于产品。