Abstract:

Objective To investigate the distribution and spreading speed of niclosamide spreading oil，as well as its effect against cercariae of Schistosoma japonicum. Methods The foamed plastic with a diameter of 4 mm served as a buoyage，which was placed at the center of the still water surface. The niclosamide spreading oil was dropped at 0.5 cm from the buoyage，the float? ing distance of the buoyage was observed，and the spreading speed and area of the niclosamide spreading oil were measured. A cy? lindrical bucket（at a diameter of 40 cm and height of 50 cm）was filled with de?chlorinated water at a temperature of 25±1 ℃， and then 60 μl of the spreading oil was dropped at the center of the water surface. At 10 cm and 20 cm from the center，1 ml water was sampled at water depths of 10，20，30，40 cm and 50 cm，respectively，and the niclosamide concentrations were determined by using high?performance liquid chromatography in each sample. The niclosamide spreading oil was diluted into solutions at effec? tive concentrations of 1.25 mg/L and 0.63 mg/L with ethanol，and then 10 μl of each solution was added to 24?well plates which contained S. japonicum cercariae to yield the niclosamide concentration of 6.25×10?3 mg/L and 3.13×10?3 mg/L per well，respective? ly. The survival of the cercariae was observed at different time. Results The spreading speeds and areas were 59，55，71，90， 111，122 cm/s and 153 cm/s，and 5.31，5.89，7.07，10.06，12.56，15.20 m2 and 16.61 m2 ，respectively，while dropping 20，30，40，50，60，70 μl and 80 μl of the niclosamide spreading oil on water surface. The spreading showed an accelerating trend with the increasing dropping volume，and there was a good linear relationship observed between them. In addition，the spreading area also enlarged with the increase in the dropping volume. After dropping 60 μl of the niclosamide spreading oil on water sur? face，the peak concentration of niclosamide reached 1.27 mg/L on water surface，and remained more than 0.07 mg/L 2 h later. However，the concentration of niclosamide was all lower than 0.04 mg/L at 10 cm under surface or more. Following the treatment with 6.25×10?3 mg/L of niclosamide spreading oil for 1 min，all the cercariae were dead，while the mortality rates of the cercariae were 0，1.39%，13.89%，19.44%，43.06%，69.44% and 79.17% at 1，2，3，5，10，20 min and 30 min，respectively，after the treatment with 3.13×10?3 mg/L of the drug. Conclusions The niclosamide spreading oil is fast to spread and is kept retention for a long time on water surface，and exhibits high activity against S. japonicum cercariae，and it can be used for killing the cercariae on water surface and interrupting the transmission of schistosomiasis in the endemic field.

Key words: Niclosamide；Spreading oil；Cercaricidal activity；High?performance liquid chromatography（HPLC）

摘要：

目的 观察了解氯硝柳胺展膜油剂水面铺展速度、 水面分布和水面杀尾蚴效果。 方法 取直径4 mm的泡沫塑料作为浮标， 置于大型静止水面中心处， 待静止后， 在距浮标0.5 cm处滴加氯硝柳胺展膜油剂， 开始计时并测定浮标在水面漂浮距离， 计算氯硝柳胺展膜油剂的铺展速度及面积。将塑料桶 （直径40 cm， 高50 cm） 装满脱氯水后， 水温 （25±1）℃， 待水体静止后在水表面圆心处滴加氯硝柳胺展膜油剂60 μl。分别在距离滴加展膜油剂处的水体表面10 cm和20 cm， 并且水深10、 20、 30、 40 cm和50 cm处提取水样1 ml， 采用高效液相色谱法测定水样中氯硝柳胺浓度。将氯硝柳胺展膜油剂用乙醇稀释成有效浓度为1.25 mg/L和0.62 mg/L的溶液， 各取10 μl溶液加入含有尾蚴的24孔培养板中， 使各孔中氯硝柳胺浓度分别为6.25×10-3 mg/L和3.13×10?3 mg/L， 观察不同时间尾蚴存活情况。 结果 氯硝柳胺展膜油剂滴入量为20、 30、 40、 50、 60、 70 μl和80 μl时， 铺展速度分别为59、 55、 71、 90、 111、 122 cm/s和153 cm/s， 铺展面积分别为5.31、 5.89、 7.07、 10.06、 12.56、 15.20 m2 和16.61 m2 ， 且随着滴入量的增加， 铺展速度呈加快趋势， 铺展面积相应增加， 铺展速度与滴入量成良好的线性关系。水表面滴入氯硝柳胺展膜油剂60 μl后， 其浓度最高可达1.27 mg/L， 2 h后浓度仍维持在0.07 mg/L以上。距离水面10 cm以下水体中氯硝柳胺浓度均< 0.04 mg/L。氯硝柳胺展膜油剂浓度为6.25×10-3 mg/L时， 1 min尾蚴内全部死亡； 当浓度为3.13×10-3 mg/L时， 1、 2、 3、 5、 10、 20 min和30 min尾蚴死亡率分别为0、 13.89%、 19.44%、 43.06%、 69.44% 和79.17%。结论 氯硝柳胺展膜油剂铺展速度快、 水面滞留时间长， 具有较好的表面杀蚴作用， 可用于现场水面杀尾蚴， 阻断血吸虫病的传播。

关键词: 氯硝柳胺； 展膜油剂； 杀尾蚴； 高效液相色谱法 （HPLC）