Chemical composition, insecticidal and in vitro anthelmintic activitiesof Ruta chalepensis (Rutaceae) essential oil

Abstract

Antipathogenic properties of plants’ essential oils have been investigated to substitute for drugs henceovercome drug resistance. This study investigated the insecticidal and antigastrointestinal parasite effectsof fresh leaves and flower essential oils of Ruta chalepensis.Determination of chemical composition revealed that leaves and flowers essential oils samples weredominated by ketone particularly 2-undecanone derivative accounting for 85.94 and 89.89% of leavesand flowers oils, respectively.The insecticidal activity of both leaves and flowers essential oils was assessed in terms of larvicidal effectappreciated by contact against third and fourth instars larvae of Orgyia trigotephras and was comparedwith a standard commercial chemical insecticide Delta-metrine “Decis”. Mean time of mortality (MMT)of third instar larvae obtained after treatment with a concentration of 0.5% of flower oil was 1.40 min,higher than, for leaf oil (MMT = 1.27 min; p < 0.001). Mean time of mortality of the fourth instar larvae,obtained after treatment with flower oil at the same concentration was 42.53 min, higher than, that forleaf oil (MMT = 20.68 min; p < 0.001). The MMT of the two instars larvae were shorter compared with theMMT of larvae treated with Decis (p<0.001) while, ethanol induced no toxic effect on larvae.In vitro anthelmintic effects against Haemonchus contortus from sheep were ascertained by egg hatchingand worm motility inhibitions compared with a reference drug albendazole. At all tested concentrations(0.125, 0.25, 0.5 and 1 mg/mL), both essential oils showed ovicidal activity. Leaves essential oil (inhibitoryconcentration (IC50) = 0.145 mg/mL) showed higher inhibitory effects on egg hatching than flowers essen-tial oil (IC50= 0.398 mg/mL). After 6 h and 8 h of exposure, the flowers essential oil at 1 mg/mL induced33.3 and 87.5% inhibition motility, respectively. At the same concentration and exposure times, essentialoil from leaves induced 29.1 and 75% inhibition motility respectively. Results highlight that 2-undecanonemay be a potential antipathogenic constituent.The overall findings of the current study indicated that R. chalepensis essential oil has a potential insecti-cidal and anthelmintic benefit and further in vitro and in vivo trials against different species and stages arerequired to make use of this plant for the control of insect pests and gastrointestinal nematode parasites