Kenawy El-Refaie, Rizk El-Sayed
Chemistry Department, Faculty of Science, Tanta University, Tanta, Egypt.
Macromol Biosci. 2004 Feb 20;4(2):119-28. doi: 10.1002/mabi.200300003.
Schistosomiasis is one of the most important public health problems in many developing countries. The present study was conducted to investigate the effect of the polymeric niclosamide formulations against Biomphalaria alexandrina snails, the intermediate host of Schistosoma mansoni in Egypt. Three new polymeric formulations were prepared for the molluscicide niclosamide. The formulations were prepared either by the chemical modifications of poly(glycidyl methacrylate) or by physical entrapment of the niclosamide in calcium alginate beads. The release of the niclosamide from the polymeric formulations was investigated. The activity of the prepared formulations against Biomphalaria alexandrina was investigated. The results obtained revealed higher potency for polymerized niclosamide B3 than B1; the lowest potency was revealed for B2. After an exposure period of 24 hours, LC(50) values were 0.073, 0.098 and 1.09 ppm for B3, B1 and B2, respectively. In addition, the molluscicidal potency of the test polymeric niclosamide was age-dependent, where old snails were more tolerant to the test solutions than young and newly hatched snails. The results also indicated that the molluscicidal activity of B3 was extended for 21 days and 17 days for B1, compared with 5 days for free niclosamide. However, the molluscicidal potency of the polymerized niclosamide was increased after boiling for one hour, and was increased with increasing the pH of the medium to pH 9. In addition, their potency was increased with decreasing the water hardness concentrations (CaCO(3)).Molluscicidal activity of free niclosamide and its polymeric formulations vs. exposure time.
血吸虫病是许多发展中国家最重要的公共卫生问题之一。本研究旨在调查聚合物氯硝柳胺制剂对埃及曼氏血吸虫中间宿主亚历山大双脐螺的影响。制备了三种新型聚合物氯硝柳胺杀螺剂制剂。这些制剂通过聚甲基丙烯酸缩水甘油酯的化学修饰或通过将氯硝柳胺物理包埋在海藻酸钙珠粒中制备。研究了氯硝柳胺从聚合物制剂中的释放情况。研究了所制备制剂对亚历山大双脐螺的活性。所得结果显示，聚合氯硝柳胺B3的效力高于B1；B2的效力最低。暴露24小时后，B3、B1和B2的LC(50)值分别为0.073、0.098和1.09 ppm。此外，测试的聚合物氯硝柳胺的杀螺效力与年龄有关，老龄螺比幼龄螺和新孵化的螺对测试溶液的耐受性更强。结果还表明，B3的杀螺活性持续21天，B1持续17天，而游离氯硝柳胺的杀螺活性持续5天。然而，聚合氯硝柳胺在煮沸1小时后杀螺效力增加，并且随着培养基pH值升高至9而增加。此外，随着水硬度浓度（碳酸钙）降低，其效力增加。游离氯硝柳胺及其聚合物制剂的杀螺活性与暴露时间的关系。
