Chemical Composition and Biological Activities of Essential Oils and Organic Extracts from Fresh and Sun-Dried Citrus limon Peels

The present study deals with the characterization of essential oils extracted from both fresh and sun-dried lemon (citrus limon (L.) Burm.f) peels by hydrodistillation, followed by extraction with ether or ethyl acetate, yielding four essential oil samples. The extraction yield varied between 0.1 and 1.65%. The essential oils constituents were identified using GC/MS analysis; limonene was the major compound ranging between 3.75 and 76.78%. In addition, ethyl acetate and methanol extracts were prepared from sun-dried lemon peels, and characterized by HPLC–PDA-ESI–MS. Four flavanoneO-diglycosides (neoreiocitrin, neohespiridin, melitidin and naringin), three flavone di-C-glycosides(diosmetin-6,8-di-C-glycoside, apigenin-6,8-di-C-glycoside, di-C-glycosideflavone), two flavone O-diglycosides (vicenin 2, neodiosmin), three polymethoxyflavones (tangeretin, nobiletin, 5,6,7,4′-tetramethoxyflavone), and two coumarins (scoparin, isomeranzin) were identified. Lemon peels ethyl acetate extract exhibits a powerful antioxidant activity (IC50 = 0.09 µg/ mL) compared to those of vitamin E (IC50 = 0.017 µg/ mL) and BHT (IC50 = 0.026 µg/ mL). On the other hand, essential oils from fresh and sun-dried lemon peels as well as organic extracts exhibited interesting antimicrobial activities against Bacillus cereus, B. subtilis, Staphylococcus aureus (Gram+) and Salmonella enterica, Escherichia coli, Klebsiella pneumoniae (Gram−). Lemon peels would be used in the agro-food industry as alternative to the undesirable chemical additives.