One known compound trans-ferrulate (compound 1) together with fatty acids derivatives were isolated from the leaves of plant Prosopis juliflora. It is an invasive plant found in dry regions of Kenya mainly Baringo, Turkana, Tana river and other regions. The plant has been reported to possess many phytochemicals, some of which are assumed 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 grounded into powder using a mill and then grounded leaves were extracted using methanol 1:1 dichloromethane and methanol sequentially for 24 hours in each case. The extracts were then concentrated using rotary evaporator 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. 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 have provided credence to the use of the leaves of this plant as natural pesticides that are ecofriendly to the environment.

Keywords: P. juliflora, trans-ferrulate, insecticidal activity