National Center for Natural Products Research (NCNPR), and ∥Department of Pharmacognosy, School of Pharmacy, University of Mississippi , University, Mississippi 38677, United States.
J Agric Food Chem. 2013 May 1;61(17):4101-7. doi: 10.1021/jf400246a. Epub 2013 Apr 22.
The evaluation of 10 essential oils of geranium, Pelargonium graveolens (Geraniaceae), were all shown to have repellent activity against nymphs of the medically important lone star tick, Amblyomma americanum (L.). The biological tests were carried out using a vertical filter paper bioassay, where ticks must cross an area of the paper treated with repellent to approach host stimuli. One of the essential oil samples that repelled >90% of the ticks at 0.103 mg/cm(2) was selected for further fractionation studies. The sesquiterpene alcohol, (-)-10-epi-γ-eudesmol, was isolated and identified by spectral methods. (-)-10-epi-γ-Eudesmol at 0.103 and 0.052 mg of compound/cm(2) of filter paper repelled 90 and 73.3% of the ticks, respectively. (-)-10-epi-γ-Eudesmol exhibited similar repellency to the reference standard N,N-diethyl-meta-toluamide (DEET) at concentrations of ≥0.052 mg of compound/cm(2) of filter paper, with (-)-10-epi-γ-eudesmol losing much of its repellency at 0.026 mg of compound/cm(2) and DEET at 0.013 mg of compound/cm(2). Isomenthone and linalool did not repel ticks at the concentrations tested. Most repellents are marketed with much higher concentrations of active ingredient than the concentrations of the natural repellents tested herein; therefore, effective compounds, such as (-)-10-epi-γ-eudesmol, found in geranium oil, have the potential for commercial development.
评估了 10 种天竺葵（天竺葵科）精油，它们对重要的孤星蜱（美洲孤星蜱）的若虫均具有驱避活性。生物测试采用垂直滤纸生物测定法进行，蜱必须穿过涂有驱避剂的纸张区域才能接近宿主刺激。在 0.103mg/cm²下，有 1 种精油样品能驱避超过 90%的蜱，因此被选中进行进一步的馏分研究。倍半萜醇（（-）-10-表-γ-桉叶醇）通过光谱方法分离和鉴定。（-）-10-表-γ-桉叶醇在 0.103 和 0.052mg 化合物/cm²的滤纸上分别驱避 90%和 73.3%的蜱。（-）-10-表-γ-桉叶醇在浓度≥0.052mg 化合物/cm²的滤纸上与参考标准 N,N-二乙基间甲苯酰胺（DEET）表现出相似的驱避性，在 0.026mg 化合物/cm²的（-）-10-表-γ-桉叶醇和 0.013mg 化合物/cm²的 DEET 下，其驱避性丧失很多。异薄荷酮和芳樟醇在测试浓度下均不驱避蜱。大多数驱避剂的上市浓度都高于本文测试的天然驱避剂的浓度；因此，天竺葵油中发现的有效化合物，如（-）-10-表-γ-桉叶醇，具有商业开发的潜力。
