Odalo Josiah O, Omolo Maurice O, Malebo Hamisi, Angira John, Njeru Patrick M, Ndiege Isaiah O, Hassanali Ahmed
Chemistry Department, School of Pure and Applied Sciences, Kenyatta University, Nairobi 00100, Kenya.
Acta Trop. 2005 Sep;95(3):210-8. doi: 10.1016/j.actatropica.2005.06.007.
Volatile oils extracted by hydrodistillation from six plant species growing in the Kenyan coast, Croton pseudopulchellus Pax, Mkilua fragrans Verdc. (Annonaceae), Endostemon tereticaulis (poir.) Ashby, Ocimum forskolei Benth., Ocimum fischeri Guerke and Plectranthus longipes Baker (Labiateae), were evaluated for repellency on forearms of human volunteers against Anopheles gambiae sensu stricto. All oils were found to be more repellent (RC50 range = 0.67-9.21 x 10(-5) mg cm(-2)) than DEET (RC50 = 33 x 10(-5) mg cm(-2)). The individual components of the oils were identified by GC-MS and GC co-injections with authentic standards. The repellency of 15 of the main constituents of the different oils (which had not been previously assayed) was evaluated. Although some of these showed relatively high individual repellencies, none was comparable to the parent essential oils. Partial synthetic blends of selected constituents with moderate or relatively high individual repellency against the vector were also assayed. Four of these exhibited activities comparable to or higher than those of the corresponding parent oils, indicating interesting blend effects in the repellent action of the oils against the mosquito. The implication of these results in the utilization of the plants is discussed.
采用水蒸馏法从肯尼亚海岸生长的六种植物中提取挥发油，这六种植物分别是巴豆（Croton pseudopulchellus Pax）、香花暗罗（Mkilua fragrans Verdc.，番荔枝科）、圆柱状喉药花（Endostemon tereticaulis (poir.) Ashby）、福氏罗勒（Ocimum forskolei Benth.）、费氏罗勒（Ocimum fischeri Guerke）和长柄香茶菜（Plectranthus longipes Baker，唇形科），对这些挥发油在人类志愿者前臂上针对冈比亚按蚊（Anopheles gambiae sensu stricto）的驱避作用进行了评估。结果发现，所有挥发油的驱避效果（RC50范围为0.67 - 9.21×10⁻⁵毫克/平方厘米）均优于避蚊胺（RC50 = 33×10⁻⁵毫克/平方厘米）。通过气相色谱 - 质谱联用仪（GC - MS）以及与标准品的气相色谱共注入法对挥发油的各个成分进行了鉴定。评估了不同挥发油中15种主要成分（此前未进行过测定）的驱避作用。尽管其中一些成分显示出相对较高的个体驱避活性，但没有一种能与母体精油相媲美。还对具有中等或相对较高个体驱避活性的选定成分的部分合成混合物针对该媒介的驱避作用进行了测定。其中四种混合物表现出与相应母体精油相当或更高的活性，表明这些挥发油在针对蚊子的驱避作用中存在有趣的混合效应。讨论了这些结果对这些植物利用的意义。
