中文摘要：

为测定薄荷中杀螨活性物质的毒力,分离鉴定该物质的分子结构,利用甲醇、氯仿和石油醚3种溶剂在常温下进行提取后,用液-液萃取法萃取,并用硅胶层析和薄层层析（TLC）结合碘显色法进行分离纯化,同时用玻片浸渍法对活性物质跟踪;最后采用紫外分光光度法（UV）、液相色谱法（HPLC）、红外色谱（RI）和质谱（MS）等技术对该物质进行鉴定。研究发现薄荷地上部分的石油醚粗提物对朱砂叶螨具有很强的毒杀作用,当浓度为1mg.mL-1时,24h内对成螨的致死率为87.05%,卵为93.16%。经Duncans检验,3种不同溶剂的粗提物对成螨及卵的致死率差异显著（P〈0.05）。同时发现薄荷地上部的甲醇、氯仿提取物杀螨效果相对较差,24h致死率仅为28.51%与10.73%。用甲醇对石油醚粗提物进行液液萃取后发现,杀螨活性物质主要集中在极性较弱的石油醚中,其对成螨24h的触杀率高达93.75%。对石油醚萃取物进行分离,共得到8段流分。利用生物活性跟踪,得到一种具有较高杀螨活性的样品V,其对成螨触杀的LC50值为0.5464mg.mL^-1,95%置信区间为0.3268～0.9134mg.mL^-1。经紫外和高压液相色谱分析,该样品纯度达到89.16%;质谱检测该物质的分子离子峰为414,数据库显示该物质为甾醇环状结构。红外分析显示该物质在1160,1450,1380,1700cm^-1等处有明显特征峰,初步确定该化合物为β-谷甾醇。

英文摘要：

The objective of this study was to measure the toxicity of active acaricidal substance of Mentha piperita extracts. Leaves of Mentha piperita were extracted using petroleum ether,chloroform and methanol respectively as solvents. Liquid-liquid partition technique was used to separate the chemical compounds. The active acaricidal components were seperated by silica gel column chromatography and thin layer chromatography （TLC）. The bioactivity was traced by treating Tetranychus cinnabarinus adults and eggs in vitro and testing the acaricide. Finally, the components of active acaricidal substance was identified by using UV photospectrum, HPLC, IR and MS methods. The effect of acaricidal active substance extracted from Mentha piperita against the adults of Tetranychus cinnabarinus was examined. Compared with those crude extracts with chloroform and methanol, the substance extracted using petroleum ether was more effective, with mortality rate of 87.05 % against the adult mites and 93.16 % against the eggs. The Duncan＇s test showed that the contact toxicity of the crude extracts from different solvents was significantly different from each other （ P 〈 0.05）. A liquid-liquid partition from petroleum ether extracts indicated that the active acaricidal substance existed in the petroleum ether fraction. The concentrated extracts of petroleum ether was separated into eight fractions, among which the fraction V produced significantly stronger acaricidal activity than other fractions. The mean half lethal concentration （ LC50 ） was 0. 546 4 mg·mL^-1 and 95 % confidence limit was 0. 326 8 - 0. 913 4mg·mL^-1. Purity of the purified compound was 89.16% by HPLC. IR showed that there were four significant peaks at 1 160,1 450,1 380 and 1 700 cm^-1. MS detection showed that the molecular mass of the fraction V was 414 with a steroid structure. The spectrum futher showed that the active acaricidal substance isolated from Mentha piperita extracts likely was a β-sitosterol.