On the genuineness of citrus essential oils. Part LIII. Determination of the composition of the oxygen heterocyclic fraction of lemon essential oils (Citrus limon (L.) Burm. f.) by normal-phase high performance liquid chromatography

The oxygen heterocyclic fraction of cold-pressed lemon essential oils has been studied by normal-phase HPLC. The components of the fraction have been isolated by column chromatography, TLC and semipreparative HPLC with recycle. The identification of the isolated components has been carried out by H-1-NMR and mass spectrometry. Three coumarins (5-geranyloxy-7-methoxycoumarin, citropten, 5-isopentenyloxy-7-methoxycoumarin) and ten psoralens (bergamottin, 8-geranyloxypsoralen, oxypeucedanin, byakangelicol, oxypeucedanin hydrate, byakangelicin, imperatorin, phellopterin, isoimperatorin, 5-isopent-2'-enyloxy-8-(2',3'-epoxyisopentyloxy)-psoralen) have been isolated and identified. The main components were bergamottin (160-291 mg/100 g of oil) and 5-geranyloxy-7-methoxycoumarin (180-250 mg/100 g of oil). Moreover, herniarin, a coumarin characteristic of lime essential oil, has been detected. Herniarin had been reported previously in essential oils obtained from Citrus limon L. var. Eureka. (C) 1998 John Wiley & Sons, Ltd.