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 semi- preparative HPLC with recycle. The identi®cation of the isolated components has been carried out by 1H-NMR and mass spectrometry. Three coumarins (5-geranyloxy-7-methoxycoumarin, citropten, 5-isopente- nyloxy-7-methoxycoumarin) and ten psoralens (bergamottin, 8-geranyloxypsoralen, oxypeucedanin, byakange- licol, oxypeucedanin hydrate, byakangelicin, imperatorin, phellopterin, isoimperatorin, 5-isopent-20-enyloxy-8- (20,30-epoxyisopentyloxy)-psoralen) have been isolated and identi®ed. 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