Comparative Phytochemical Composition and Antimicrobial Activity of Citrus Peel Essential Oils and Phenolic Compounds

Abstract

Background: Antimicrobial resistance is imposing an alarming public health threat in regard to the irrational use of the currently available antibiotics and the lack of new antimicrobi-als. Objective: The current study aims to comparatively investigate the antimicrobial potential and phytochemical compositions of citrus peel essential oils (EOs) and phenolic compounds (PCs) as an approach to combat life-threatening bacterial and fungal infections. Methods: Citrus EOs and PCs were extracted from Citrus aurantifolia, Citrus reshni, Citrus lati-folia and Citrus paradisi peels and phytochemically characterized by GC-MS and HPLC, respec-tively. The antimicrobial potential of citrus peel EOs and PCs was tested against Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes, Escherichia coli O157:H7, Pseudomonas ae-ruginosa, Salmonella typhimurium and Candida albicans using disc diffusion and broth micro-dilution assays. Results: The compositional analysis of citrus peel EOs revealed that limonene was the major volatile constituent, comprising 81.38%, 79.39%, 76.40% and 52.35% of grapefruit, mandarin, orange and lemon EOs, respectively. In addition, naringenin was the most abundant PC in grape-fruit, orange and mandarin peel methanolic extracts, whereas catechin was the major PC in lemon peel. Lemon EO displayed the highest inhibitory effects against the investigated Gram-positive and Gram-negative bacteria as well as Candida albicans. Moreover, mandarin PCs exhibited the highest antibacterial effects, while orange PCs displayed the highest anticandidal effects. Fur-thermore, Gram-positive bacteria displayed higher sensitivity to both citrus peel EOs and PCs. Conclusion: Citrus peel extracts possess versatile bioactive compounds that can be utilized as promising antimicrobial candidates. other: -