Department of Entomology, China Agricultural University, Haidian District, Beijing 100193, China.
Molecules. 2011 Aug 25;16(9):7320-30. doi: 10.3390/molecules16097320.
The screening of several Chinese medicinal plants for insecticidal principles showed that essential oil of Rhododendron anthopogonoides flowering aerial parts possessed significant toxicity against maize weevils, Sitophilus zeamais. A total of 37 components were identified in the essential oil and the main constituents of the essential oil were 4-phenyl-2-butanone (27.22%), nerolidol (8.08%), 1,4-cineole (7.85%), caryophyllene (7.63%) and γ-elemene (6.10%), followed by α-farnesene (4.40%) and spathulenol (4.19%). Repeated bioactivity-directed chromatographic separation on silica gel columns led us to isolate three compounds, namely 4-phenyl-2-butanone, 1,4-cineole, and nerolidol. 4-Phenyl-2-butanone shows pronounced contact toxicity against S. zeamais (LD₅₀ = 6.98 mg/adult) and was more toxic than either 1,4-cineole or nerolidol (LD₅₀ = 50.86 mg/adult and 29.30 mg/adult, respectively) against the maize weevils, while the crude essential oil had a LD₅₀ value of 11.67 mg/adult. 4-Phenyl-2-butanone and 1,4-cineole also possessed strong fumigant toxicity against the adults of S. zeamais (LC₅₀ = 3.80 mg/L and 21.43 mg/L) while the crude essential oil had a LC₅₀ value of 9.66 mg/L.
几种中草药的杀虫活性筛选表明，马缨杜鹃开花地上部分的精油对玉米象、玉米象具有显著毒性。从精油中鉴定出 37 种成分，精油的主要成分是 4-苯基-2-丁酮（27.22%）、橙花叔醇（8.08%）、1,4-桉叶素（7.85%）、石竹烯（7.63%）和γ-榄香烯（6.10%），其次是α-法呢烯（4.40%）和斯巴醇（4.19%）。硅胶柱反复生物活性导向色谱分离，我们分离得到三种化合物，即 4-苯基-2-丁酮、1,4-桉叶素和橙花叔醇。4-苯基-2-丁酮对玉米象表现出明显的触杀毒性（LD₅₀=6.98mg/成虫），比 1,4-桉叶素或橙花叔醇（LD₅₀分别为 50.86mg/成虫和 29.30mg/成虫）对玉米象更具毒性，而粗提精油的 LD₅₀值为 11.67mg/成虫。4-苯基-2-丁酮和 1,4-桉叶素对玉米象成虫也具有很强的熏蒸毒性（LC₅₀分别为 3.80mg/L 和 21.43mg/L），而粗提精油的 LC₅₀值为 9.66mg/L。
