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.

植物可以合成多种具有生物活性的次生代谢产物，以防御害虫和病原体。红al木（Alnus rubra）的树皮，根和叶提取物在传统医学和卫生中具有悠久的使用历史。二芳基庚烷类化合物，尤其是牛至黄素（（5S）-1,7-双（3,4-二羟基苯基）-5-（β-D-吡喃吡喃糖基氧基）-庚烷-3-酮）已被确定为主要的生物活性成分。关于二芳基庚烷类化合物的抗氧化剂，抗真菌剂和抗癌活性的报道已成为研究的重点。最新数据表明，高的牛至黄素浓度与赤of红叶对西部毛毛虫的抗性有关（Malacosoma californicum）的脱叶。在这里，我们直接测试该化合物对食叶昆虫的影响。使用鳞翅目毛虫在昆虫选择和毒性试验中检查了纯化的牛至蛋白。该化合物对卷心菜（Trichoplusia ni），白斑（Orgyia leucostigma），秋天的网蠕虫（Hyphantria cunea）和苜蓿分枝杆菌（M. californicum）具有显着的拒食活性。浓度相当于先前实验中抵抗力最强的der木克隆的Oregonin含量。仅对白菜弯头幼虫进行了毒性试验，但未发现接触或摄入的毒性。我们的结果表明，在生长季节早期，在红al木叶片中发现的Oregonin含量可能有助于保护红der木免受食叶昆虫的侵害。