Antioxidative activity of the tree of heaven leaves (Ailanthus altissima (Mill.) Swingle)

Ailanthus altissima (Mill.) Swingle, commonly called the tree of heaven (Simaroubaceae), is an invasive woody plant species. Originally from northern and central China, it has spread to Europe, America, Australia, and other areas, where it has become a noxious weed. In Europe, A. altissima is one of the most invasive species, harming local biodiversity . It competes with native plants, inhibits their seed germination and seedling growth, and is less susceptible to herbivorous insects. The tree of heaven leaves were used as a source for extraction, chemical characterization, and encapsulation of leaf extracts. Obtained crude leaf extract (CLE) and nano-capsulated leaf extract (ELE) were applied in different concentrations to test feeding deterrent activity, digestive and contact toxicity as well as their effect on larval behavior, namely, growth and feeding indices, and molting of the spongy moth larvae. Antioxidative activity was investigated using two commonly applied in vitro assays, that differ in their working principles, where ABTS ((2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) test served to assess free radical scavenging ability, while cupric ion reducing antioxidant capacity assay (CUPRAC) was employed as an electron transfer-based test measuring the substance ability to reduce Cu2+ to Cu+. Results of the antioxidative activity was used for the explanation of the spongy moth larvae behavior.臭椿（Ailanthus altissima (Mill.) Swingle）俗称天堂树，隶属于苦木科（Simaroubaceae），是一种入侵性木本植物。其原生分布区为中国华北与华中地区，现已扩散至欧洲、美洲、澳洲等全球多地，并成为有害入侵杂草。在欧洲范围内，臭椿是危害最为严重的入侵物种之一，会对本土生物多样性造成显著损害。该物种通过与本土植物竞争生存资源、抑制其种子萌发与幼苗生长实现入侵，同时自身对植食性昆虫的取食具有更强的抗性。 本研究以天堂树叶片为实验材料，开展了叶片提取物的提取、化学表征及纳米包裹制备工作。研究获得了粗叶片提取物（crude leaf extract, CLE）与纳米包裹叶片提取物（nano-capsulated leaf extract, ELE），并设置不同浓度梯度，测试二者对舞毒蛾幼虫的取食忌避活性、消化毒性与触杀毒性，以及对幼虫行为的影响，具体包括幼虫的生长、取食指标以及蜕皮情况。此外，本研究采用两种原理不同的经典体外实验评估提取物的抗氧化活性：ABTS（2,2'-联氮-双(3-乙基苯并噻唑啉-6-磺酸)）实验用于检测自由基清除能力，而铜离子还原抗氧化能力实验（CUPRAC）作为基于电子转移机制的检测手段，用以衡量待测物质将Cu²+还原为Cu+的能力。本研究通过抗氧化活性的实验结果，阐释了舞毒蛾幼虫的行为变化机制。