Phytochemical Investigation of Prosopis Juliflora Leaves Extracts and Their Insecticidal Activity

Abstract

One known compound trans-ferrulate (compound 1) together with fatty acids derivatives were isolated from the leaves of Prosopis juliflora. P juliflora is an invasive plant found in dry regions of Kenya mainly Baringo, Turkana and Tana River. The plant has been reported to possess many phytochemicals, some of which are known to possess insecticidal activities. The leaves were collected from Baringo County, then put in cotton bags and transported to University of Kabianga, Biological Sciences Department for taxonomical identification. The leaves were then washed using running water then air-dried. The dried leaves were ground into powder using a mill and then sequentially extracted using methanol 1:1 dichloromethane and methanol for 24 hours in each case. The extracts were then concentrated using rotary evaporator at 35 0C – 64.7 0C to obtain their respective crude extracts. Repeated column chromatography of fraction 1, yielded trans-ferrulate (compound 1) a cinamic acid derivative having both methoxy and hydroxy substituents on the phenyl ring. Fractions F1, F10 and F11 exhibited significant activity against adult aphids, with corresponding percentage mortalities of 90 ± 2.03, 95 ± 2.03 and 95 ± 2.25 % respectively. The insecticidal activities of these extracts could be attributed to the conjugation in the benzene rings as well as the activation caused by the ring activators (-OH and -OCH3 groups) on the benzene ring. The findings of this research credence to the use of the leaves of this plant as natural pesticides that are ecofriendly