Synthesis And Acaricidal Activity Of7-hyderoxy-4-methycomarin Derivatives

7-Hydroxy-4-meythcomarin is a kind of heterocyclic aromatic compound, widely usedin industry, agriculture, medicine and other fields, and also a primarily raw medicine ofcholeric drug. In2007, Dou Chuanna extracted a component from Artemisia scoparia WaldstKit which has an efficient of acaricidal activity—hymecromone. According to the structurecharacteristics of hymecromone, the experiment was conducted by designing somehymecromone derivatives to evaluate their acaricidal activity. The main aim of this researchis to find a compound with high acaricidal activity and offer scientific basis for furtherresearch and development of new animal acaricidal drugs.（1）The synthesis and study on acaricidal activity of hymecromone derivatives invitro: In order to improve the acaricidal activity of hymecromone, eight kinds ofhymecromone derivatives were synthesized with hymecromone by alkylation and acylation.The derivatives were dissolved with10%Tween80and10%dimethylsulfoxide, and dilutedinto0.5mg/mL. Then, the structural characterizations of them were confirmed by1H-NMRand13C-NMR, and the acaricidal activity of derivatives in vitro was determined. The resultsshowed that the mortality rates of psoroptes cuniculi in3,6,8-tribromo-7-hydroxy-4-methylcoumarin,8-acetyl-7-hydroxy-4-methylcoumarin,7-(4-chlorobenzyloxy)-4-methyl-coumarin and7-exthoxy-4-methylcoumarin groups were100%,73.0%,68.3%and66.2%respectively within24hours. Compared with hymecromone, the difference was extremelysignificant (P<0.01). The mortality rates in7-(2-phenylethoxy)-4-methylcoumarin and7-benzoxy-4-methylcoumarin groups were35.5%and34.7%, and the difference wassignificant compared with hymecromone (P<0.05).（2）Study on microemulsion preparation and acaricidal activity of3,6,8-tribromo-7-hydroxy-4-methylcoumarin: According to the result of acaricidal activity study ofhymecromone derivatives in vitro,3,6,8-tribromo-7-hydroxy-4-methylcoumarin micro-emulsion was prepared, and its acaricidal activity in vivo was determined. The result showedthat the external ears of tested rabbits were smooth and clean, with a little or no scar in earcanal after7days by giving0.5mg/mL3,6,8-tribromo-7-hydroxy-4-methylcoumarinmicroemulsion and0.5mg/mL ivermectin in vivo, and no living mites were found by microscopy. On the14th day, there was no scar in ear canal. It is indicated that the therapeuticeffect of3,6,8-tribromo-7-hydroxy-4-methylcoumarin microemulsion corresponded toivermectin at0.5mg/mL (P＞0.05).