HPLC-PDA-MS and NMR characterization of a hydroalcoholic extract of Citrus aurantium L. var. amara peel with antiedematogenic activity

The phytochemical profile of a hydroalcoholic extract of Citrus aurantium var. amara L. peel, used as herbal medicine, was characterized by HPLC-PDA-MS. Two di-C-glycosyl flavones (vincenin II and diosmetin 6,8-di-C-glucoside), a series of flavones (luteolin 7-O-neohesperidoside, rhoifolin, and neodiosmin), and flavanone (neoeriocitrin, naringin, and neohesperidin) 7-O-neohesperidosides and two methoxyflavones (nobiletin and tangeretin), commonly present in Citrus, were identified. Furthermore, brutieridin and melitidin, two 3-hydroxy-3-methylglutaryl flavanone glycosides, were also characterized along with rhoifolin 4′-glucoside and three coumarins (8,3′-β-d-glucopyranosyloxy-2′-hydroxy-3′-methylbutyl-7-methoxycoumarin, merazin hydrate, and isomerazin). A preparative isolation procedure followed by NMR spectroscopy confirmed the proposed structures of the major flavonoids and identified the coumarins. The phenolic content was found to be 14.8 mg mL–1, and naringin and neohesperidin were the compounds present in the highest concentration (3.6 and 2.6 mg mL–1). The extract of C. aurantium peel inhibited significantly (p < 0.05) both histamine- and dextran-induced edema in rats in a concentration-dependent manner (IC50 = 119.6 and 118.3 mg kg–1, respectively), providing evidence for the therapeutic use of C. aurantium var. amara peel.