Isolation of extracts of wormwood - effective natural insecticides of the terpenoid group

Abstract

Extracts of wormwood (Artemísia absínthium) grown in the greenhouse complex of the Institute of Phytopathology were obtained. The resulting extracts were isolated from the dried ground parts of this plant (leaves and flowering tops) by subsequent extractions with a mixture of dichloroethane, acetone and petroleum ether, as well as a mixture of methanol, chloroform and water with the addition of water and chloroform to separate the chloroform layer and purification on activated carbon. By further separation of the obtained extracts by preparative column chromatography, biologically active fractions with different contents of natural insecticides from the group of terpenoids were isolated. The content of biologically active components in various fractions was determined by the methods of chromatomass-spectrometry. It was found that a mixture of low-polarity chloroform with a minimum amount of polar methanol most fully extracts chrysanthenone and chrysanthenyl acetate, cineole and borneol, and the minimum extraction of terpenoids is observed with an increase in the content of polar methanol in the eluent containing chloroform. The insecticidal effect of the isolated fractions on the large cereal aphid (Sitobion avenae) was studied. It was found that the maximum insecticidal effect (100% death of insects) was exhibited by the fraction of terpenoids isolated during extraction with a low-polarity eluent containing chloroform with a minimum amount of methanol. It was found that the fraction of terpenoids containing a high amount of chamazulene exhibited a moderate insecticidal effect (31% of insect mortality), while fractions with a low content of this compound exhibited low insecticidal activity. It was shown that extracts of wormwood have an insecticidal effect against the pest of cereal crops, large cereal aphid and can be used as environmentally friendly natural insecticidal additives to commercial preparations.