Screening Of Anti-schistosoma Activity Of Benzoyl Hydrazides

Schistosomiasis is the second neglected parasitic disease,affecting more than 200 million people around the world.At present,the treatment of schistosomiasis mainly depends on the single drug praziquantel,but the emergence of drug resistance forces people to look for alternatives to praziquantel.Acylhydrazide compounds are favored by many chemists because of their wide insecticidal activity,and have also successfully been utilized as ultra-efficient insecticides.This paper mainly introduces the screening study on the bioactivity of benzoyl hydrazides against Schistosoma japonicum.The main research work is as follows:（1）Synthesis of benzoyl hydrazide compounds.In order to investigate the anti-schistosome activity of benzoyl hydrazide drugs,41 benzoyl hydrazide compounds were designed and synthesized by mixing N-methylphenyl hydrazide compounds and benzoyl chloride compounds with pyridine as base in ice bath at room temperature for 12 h.According to the preliminary screening of bioactivity in vitro,three main types of compounds were synthesized including 2-14～2-27,2-28～2-38,and 2-39～2-53,and the compounds were identified by IR,NMR and HRMS.（2）Study on the insecticidal activity of benzoyl hydrazide compounds.The 41 compounds were tested for anti-schistosomal activity in vitro at the concentration of 100μM.Experimental results showed have shown that halogen containing groups could enhance the insecticidal activity of drugs.According to the results of the preliminary anti-schistosomal experiments in vitro,and the LC₅₀ of five compounds with considerable anti-schistosomal activity was selected.Among the tested compounds,compounds 2-24,2-33 and 2-53 were found to be the most active compounds in vitro,the compound 2-53 with the lowest LC₅₀ value is 61.4μM.The anti-schistosomal activities of three drugs were further investigated in vivo.A single dose of 100 mg/kg was administered by gavage for 5 consecutive days on the Juvenile stage（9th day）and adult stage（35th day）respectively.Then the mice were killed on the 45th day and the worms were taken by infusing method.The worm reduction rate was calculated.The experimental results showed that compound 2-33 exhibited the best activity in the juvenile stage,with the worm reduction rate of 40%.The compound 2-24displayed the best activity in the adult stage,with the worm reduction rate of 34.1%.（3）Preliminary research on the mechanism of killing worms.In this section,we mainly explored the effect of drugs on the epidermis of worms and liver function of mice.After being incubated with compounds 2-24,2-33 and 2-53 at 100μM for 72 hours,the adult epidermis was damaged by drugs,and the ultrastructure was observed by scanning electron microscope.The results found that the damage degree was similar to that of praziquantel.The epidermis of adult was seriously being damaged,most of which was disintegrated,and the tissue structure of muscle layer was also exposed in air.Furthermore,the oral suction cup showed contraction and fold.The epidermis of Schistosoma japonicum played an important role in the absorption,metabolism and defense functions.We conferred that the destruction of the epidermis is one of the important factors for the death of Schistosoma japonicum.After intragastric administration in vivo,the mice were subjected to carry out the eyeball blood collection experiments.The blood was detected and evaluated using various indicators to determine whether the drugs have the protecting effect for the kidney and liver to mice.It was found that compounds 2-24,2-33 and 2-53 could protect the liver and reduce the number of liver worm eggs.Except for compounds 2-33 which have certain toxicity to mouse kidneys during the juvenile stage,while compounds 2-24 and 2-53 have no toxicity to mouse kidneys during both the juvenile and adult stages.