Department of Biology and Centre for Forest Biology, University of Victoria, 3800 Finnerty Road, Victoria, BC, Canada.
Ecosafe Natural Products Inc., 16-6782 Veyaness Rd., Saanichton, BC, Canada.
J Chem Ecol. 2021 Feb;47(2):215-226. doi: 10.1007/s10886-021-01244-3. Epub 2021 Jan 21.
Plants synthesize a wide range of bioactive secondary metabolites to defend against pests and pathogens. Red alder (Alnus rubra) bark, root, and leaf extract have a long history of use in traditional medicine and hygiene. Diarylheptanoids, especially oregonin ((5S)-1,7-bis(3,4-dihydroxyphenyl)-5-(β-D-xylopyranosyloxy)-heptan-3-one), have been identified as major bioactive constituents. Diarylheptanoids have become a focus of research following reports of their antioxidant, antifungal, and anti-cancer activities. Recent data suggest that high oregonin concentration is associated with resistance of red alder leaves to western tent caterpillar (Malacosoma californicum) defoliation. Here we test effects of this compound directly on leaf-eating insects. Purified oregonin was examined in insect choice and toxicity tests using lepidopteran caterpillars. The compound exhibited significant anti-feedant activity against cabbage looper (Trichoplusia ni), white-marked tussock moth (Orgyia leucostigma), fall webworm (Hyphantria cunea), and M. californicum at concentrations corresponding to oregonin content of the most resistant alder clones in previous experiments. Toxicity tests were carried out with cabbage looper larvae only, but no contact or ingested toxicity was detected. Our results suggest that oregonin at levels found in red alder leaves early in the growing season may contribute to protecting red alder from leaf-eating insects.
植物合成广泛的生物活性次生代谢物来抵御害虫和病原体。红桤木（Alnus rubra）树皮、根和叶提取物在传统医学和卫生保健方面有着悠久的应用历史。二芳基庚烷类化合物，特别是奥枯灵（（5S）-1,7-双（3,4-二羟基苯基）-5-（β-D-吡喃木糖基氧基）-庚烷-3-酮），已被确定为主要的生物活性成分。二芳基庚烷类化合物因其具有抗氧化、抗真菌和抗癌活性而成为研究的焦点。最近的数据表明，高奥枯灵浓度与红桤木叶对西部天幕毛虫（Malacosoma californicum）取食的抗性有关。在这里，我们直接在食叶昆虫上测试这种化合物的作用。使用鳞翅目幼虫进行昆虫选择和毒性试验，研究了纯化的奥枯灵。该化合物对小菜蛾（Trichoplusia ni）、白标记毒蛾（Orgyia leucostigma）、秋粘虫（Hyphantria cunea）和 M. californicum 具有显著的拒食活性，其浓度与之前实验中最具抗性的桤木克隆体中的奥枯灵含量相对应。仅对小菜蛾幼虫进行了毒性试验，但未检测到接触或摄入毒性。我们的结果表明，在生长季节早期红桤木叶中发现的奥枯灵水平可能有助于保护红桤木免受食叶昆虫的侵害。
