Screening Of Chinese Herbs With Acaricidal Activity And Studying On Acaricidal Active Compounds From Eugenia Caryphyllata

In recent years the serious " 3R " issue (residual, resistance and resurgance ) that was caused by the use of the chemical insecticide had aroused the attention from the whole society. As the enhancement of awareness of health and enviroment of the public, studies of natural drug of safty, low toxicity, unresidual and unresistance are becoming the dominant direction of acaricide development. In order to look for and develope a new acaricide, we screened the acaricidal active plants from 200 plants. Then the compound with high acaricidal activity in the bud of Eugenia caryophyllata was isolated, purified and identified. The results obtained were as follows: 1.Screening of acaricidal active plants: Acaricidal activity of industrial alcohol extract from 200 plants in 50% concentration on adult mites of P.communis cuniculi was investigated in vitro. The result showed that the crude extracts of 20 species of plants(clove, castor bean, immature bitter orange and so on)had significant activities against mites. Among them clove exhibited excellent acaricidal effect and could kill all experimental mites in 16min. 2.Pre-test for chemical constituents and Screening of acaricidal active part of clove: The possible chemical compounds of clove were checked using tube-test method. The main compounds of clove were suggested to be volatileoils and hydroxybenzene. Then the extracts of petroleum ether,chloroform,ethyl acetate,n-butanol and distilled water were extracted by solvent extraction,and whose acaricidal activity were detected by killing Psorptes communis cuniculi in vitro. The result of the acariaidal test showed that the extract of petroleum ether in 50% concentration could kill all experimental mites in 20 min. The time killing all experimental mites of the exacts of chloroform and ethyl acetate were 105 min and 53 min, respectively. The acaricidal activity of the extracts of n-butanol and distilled water were not detected in this test. The exact of petroleum ether was the acaricidal active site of Eungenia caryophyllata. 3.Isolation, purification and identification of compounds with acaricidal activity in Eugenia Caryphyllata: The exact of petroleum ether was separated into 6 parts(A,B,C,D,E and F) by silica gel column chromatography with gradually increasing polarity of petroleum ether: ethyl acetate. The part C was demonstrated to be the most effective part by acaricidal activity test in vitro,and the time for it to kill all experimental mites was about 20 min. Then three yellow oily purified substances (â… ,â…¡and â…¢) were isolated and purified from the part C by thin layer chromatography. The compound â…¢could kill all experimental mites at a mean time of only 12 min. In vitro the 50% Lethal concentration of the compound â…¢against P.communis cuniculi was investigated by K?rber's method . The result showed that the 50% Lethal concentration of it was 0.1684 mg/mL. The chemical structure of compound â…¢was identified by physicochemical property,analysis of UV and IR,and the activity compared with reference substance. The result showed that the substance â…¢was eugenol.