PHYTOCHEMICAL INVESTIGATION, AND INSECTICIDAL FORMULATION BASED ON ECHINOPS KEBERICHO MESFIN ROOT EXTRACT SUPPORTED ON MODIFIED KAOLINITE AGAINST SITOPHILUS ZEAMAIS

Abstract

The Echinops kebericho Mesfin root extract was investigated for its phytochemical constituents and its essential oil was formulated using modified and unmodified kaolinite clay as supporting material. To this effect, the petroleum ether, chloroform/methanol (1:1) and the methanol crude extracts were subjected to qualitative phytochemical screening and the results of the screening test revealed that it is rich in many secondary metabolites such as flavonoids, terpernoids, glycosides, alkaloids and phenols. One compound known as (3aR,6aR,9aR,9bR)-decahydro-4-hydroxy-3,6,9-trimethyleneazuleno[4,5-b]furan-2(9bH)-one was isolated using CC and the structure of this compound was identified using FT-IR and NMR techniques (1H-NMR, 13C-NMR and DEPT-135). Essential oil was also extracted by hydrodistilation from the E. kebericho Mesfin root and it was analyzed by GC-MS dehydrocostus lactone (25.09%), quinolin-5(6H)-one-7,8-dihydro-2-hydroxy-4,7,7-trimethyl-(10.71%) and modephene (9.07%), were the first three major constituents. The modified and unmodified kaolinite clay was characterized by SEM/EDX, TGA, FT-IR and XRD techniques. XRD and mineralogical constituents of the clay material was confirmed to be kaolinite. The unformulated essential oil and the methanol extracts were tested for insecticidal activities on the Sitophilus zeamais and the result revealed that the essential oil was more active with in 24 h of exposure time. The effect of exposure time, the formulation efficacy, the stability and the remnant effect of the formulated essential oil were tested and the result showed an improvement for insecticidal activities of the maize weevil for a long period of time with high persistence