Chemical Composition of the Essential Oils of Variegated Pink-Fleshed Lemon (Citrus x limon L. Burm. f.) and their Anti-Inflammatory and Antimicrobial Activities

Abstract

The volatile secondary metabolites of essential oils from fruit peel and leaves of variegated pink-fl eshed lemon (Citrus x limon) were investigated using GLC and GLC-MS (gas-liquid chromatography-mass spectroscopy). Altogether 141 compounds were identified and quantified, accounting for 99.59% and 96.33% of the total hydrodistilled peel and leaf oil, respectively. Limonene occurred in higher amounts in fruit peel (52.73%) than in leaf oil (29.13%). Neral (12.72%), neryl acetate (8.53%), ρ-menth-1-en-7-al (4.63%), β-pinene (6.35%), and nerol (4.42%) were the most abundant constituents in leaf oil, whereas γ-terpinene (9.88%), β-pinene (7.67%), geranial (4.44%), and neral (3.64%) dominated in the fruit peel oil. The antioxidant, anti-inflammatory, antitrypanosomal, and antimicrobial activities of the fruit peel essential oil were evaluated. The oil had a low antioxidant activity with an IC50 value of (26.66 ± 2.07) mg/ml as compared to the efficient antioxidant ascorbic acid [IC50 (16.32 ± 0.16) μg/ml]. The oil moderately inhibited soybean 5-lipoxygenase (5-LOX) with an IC50 value of (32.05 ± 3.91) μg/ml and had moderate antitrypanosomal activity [IC50 (60.90 ± 0.91) μg/ml]. In addition, moderate antimicrobial activities were detected against Gram-positive bacteria (Bacillus subtilis, Staphylococcus capitis, Micrococcus luteus), one Gram-negative bacterium (Pseudomonas fluorescens), and yeasts (Saccharomyces cerevisiae, Candida parapsilosis)