Valorization of Citrus Leaves: Chemical Composition, Antioxidant and Antibacterial Activities of Essential Oils

The objective of this study was to characterize chemical composition and functional properties of essential oils extracted from leaves of Citrus sinensis Osbeck, Citrus grandis Osbeck and Citrus aurantifolia Swingle. The essential oil of the C. sinensis and C. grandis leaves contained 44 compounds, accounted for total percentages of 94.17% and 93.78% of the oils, respectively, whereas the essential oil of the C. aurantifolia leaves had 62 compounds, accounted for 97.19% of the oil. Limonene, β-pinene, sabinene, β-ocimene, β-cubebene, terpinen-4-ol, linalool and nerol were main volatile compounds of the essential oil of the C. sinensis leaves, while the essential oil of the C. grandis contained high percentages of limonene, α-phellandrene, β-ocimene, β-caryophyllene, nerol, citronellol, geraniol, geranial and neral. The main volatile compounds of the essential oils of the C. aurantifolia leaves were Limonene, β-pinene, β-ocimene, β-caryophyllene, α-terpineol, citronellol and (+)-citronellal. The essential oil of the C. aurantifolia leaves exhibited the strongest scavenging activities (IC 50 = 1.21 mg/ml) as compared to those of the C. sinensis (IC 50 = 1.49 mg/ml) and C. grandis leaves (IC 50 = 2.18 mg/ml). The essential oil of C. grandis leaves exhibited stronger antimicrobial activities than the essential oils of C. sinensis and C. aurantifolia leaves. Graphic Abstract