Red maple leaf extracts (RME) were tested for their plant defense inducer (PDI) properties. Two extracts were obtained and compared by different approaches: RME1 using ethanol–water (30–70%, v/v, 0.5% HCl 1N) and RME2 using pure water. Both extracts titrated at 1.9 g L⁻¹ in polyphenols and infiltrated into tobacco leaves efficiently induced hypersensitive reaction-like lesions with topical accumulation of auto-fluorescent compounds noted under UV and scopoletin titration assays. The antimicrobial marker PR1, β⁻¹,3-glucanase PR2, chitinase PR3, and osmotin PR5 target genes were all upregulated in tobacco leaves following RME1 treatment. The alkaline hydrolysis of RME1 and RME2 combined with HPLC titration of gallic acid revealed that gallate functions were present in both extracts at levels comprised between 185 and 318 mg L⁻¹. HPLC-HR-MS analyses and glucose assay identified four gallate derivatives consisting of a glucose core linked to 5, 6, 7, and 8 gallate groups. These four galloyl glucoses possessed around 46% of total gallate functions. Their higher concentration in RME suggested that they may contribute significantly to PDI activity. These findings define the friendly galloyl glucose as a PDI and highlight a relevant methodology for combining plant assays and chemistry process to their potential quantification in crude natural extracts.

中文翻译：

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红枫叶中富含酚的提取物在烟草植物中诱导植物防御反应：主要活性成分的表征

对红枫叶提取物（RME）的植物防御诱导剂（PDI）特性进行了测试。获得了两种提取物，并通过不同的方法进行了比较：使用乙醇-水（30-70％，v / v，0.5％HCl 1N）的RME1和使用纯水的RME2。两种提取物在多酚中的滴定浓度均为1.9 g L ^-1，并渗入烟草叶中，可有效诱导过敏反应样病变，并在UV和scopoletin滴定试验中发现局部积累的自发荧光化合物。抗微生物标记PR1，β ^-1，3-葡聚糖酶PR2，几丁质酶PR3，和渗透蛋白PR5RME1处理后，烟草叶片中的所有靶基因均被上调。RME1和RME2的碱水解结合没食子酸的HPLC滴定表明，两种提取物中均存在没食子酸酯功能，其含量介于185和318 mg L ^-1之间。HPLC-HR-MS分析和葡萄糖测定法鉴定了由连接至5、6、7和8个没食子酸酯基团的葡萄糖核心组成的4个没食子酸酯衍生物。这四个没食子酰基葡萄糖占总没食子酸酯功能的约46％。它们在RME中的较高浓度表明它们可能对PDI活性有重要贡献。这些发现将友善的没食子酰基葡萄糖定义为PDI，并着重介绍了将植物测定法和化学过程结合到天然粗提物中的潜在定量方法的相关方法。