Isolation and identification of insecticidal components from Citrus aurantium fruit peel extract

Three active components were identified by bioassay-guided fractionation of bitter orange (Citrus aurantium L.) fruit peel petroleum ether extract. Silica gel fractionation of the extract yielded a fraction that inflicted up to 96% mortality to adults of the olive fruit fly Bactrocera oleae (Gmelin) three days post-treatment. Subsequent HPLC purification of the active fraction resulted in the isolation of three components, eluted in fractions F-222, F-224, and F-226, that induced adult mortality. Considering the data obtained from UV, FTIR, MS, and H-1 NMR spectra, they were identified as 7-methoxy-8-(3'-methyl-2'-butenyl)-2H-1-benzopyran-2-one (osthol), 4-methoxy-7H-furo[3,2-g]benzopyran-7-one (bergapten), and 4-((E)-3'-methyl-5'-(3",3"-dimethyloxiran-2"-yl)pent-2'-enyloxy)-7H-furo[3,2-g][1]benzopyran-7-one (6',7'-epoxybergamottin). Our results are in concordance with those reported in the literature and were further verified by direct comparison to authentic components. 6',7'-Epoxybergamottin was toxic when tested individually, while bergapten and osthol were found to act synergistically to 6',7'-epoxybergamottin.