Design, synthesis, and cercaricidal activity of novel high-efficient, low-toxic self-spreading PEG-N-salicylanilide derivatives against cercariae larvae of Schistosome Japonicum floating on the water surface

Novel cercaricides of PEG-N-salicylanilide derivatives that could self-spread and float on the water surface were designed and synthesized according to the particular habit of cercariae larvae of Schistosome japonicum. The structures of the cercaricides were characterized by the infrared spectra (IR), magnetic resonance ((1) H NMR), and mass spectrum (MS). The images of the floating cercaricides on the water surface were investigated by the Brewster angle microscopy (BAM). When the cercaricides were dropped on the water surface, they could spread along the air-water interface automatically and form thin membranes floating on the water surface immediately. The lethality rate of cercariae for 5a and 6a was more than 90% in 120 min at a surface concentration of 0.008 mg/cm(2) . The non-ionic surfactant-cercaricides not only showed strong cercaricidal activities against the cercariae larvae but also exhibited low toxicities, which offered an effective and environment-friendly approach for the reduction of population infection rate and the realization of schistosome control.