CHEMICAL COMPOSITION, CYTOTOXIC EFFECT, ANTIMICROBIAL ACTIVITY, AND MODE OF ACTION OF COMBINED ESSENTIAL OILS FROM CITRUS PARADISE, CITRUS SINENSIS, AND CITRUS MAYERI LEAVES
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Date
2024-10-17
Authors
Hamdan, Mahmoud Sapti
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Publisher
An-Najah National University
Abstract
Background: Plants are the most abundant primary source of active phytochemicals, which are essential for the medical treatment of diverse diseases.
Objectives: The current study aims to investigate the chemical composition, antimicrobial activity, and mode of action of combined Essential Oils (EOs) from Citrus paradise, Citrus sinensis, and Citrus meyeri leaves, and to evaluate their cytotoxicity.
Methodology: Gas chromatography-mass spectrometry identified the chemical composition, while the MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium] assay measured the EOs' cytotoxicity against HeLa, HepG2, Caco-2, and LX-2 cells. Antimicrobial activities were assessed by broth microdilution assay against one fungal and six bacterial strains. The antibacterial mechanisms of EOs from C. paradise, C. sinensis, and C. meyeri and their combinations were investigated by evaluating their effects on microbial cell constituents at MIC and 2X MIC levels, using crystal violet assays to assess biofilm formation inhibition, and performing real-time PCR to measure bacterial lysis-related gene expression.
Results: The EOs of C. meyeri, C. paradise, and C. sinensis contain 27, 20, and 32 compounds, respectively. Limonene (43.2%), β-pinene (44.5%), and sabinene (55.9%) are the most abundant compounds in these EOs, namely C. meyeri, C. paradise, and C. sinensis, respectively. The EOs showed variable antimicrobial activity, with combinations displaying synergistic effects against pathogens like Escherichia coli, Candida albicans, and Proteus vulgaris. C. meyeri EO exhibited robust anticancer activity when compared with other Citrus species studied against HeLa, HepG2, and CaCo-2 cancer cell lines. The study found that Citrus EOs and their combinations had varying effectiveness in releasing cellular constituents from microbial isolates. In the other side, the results demonstrate significant inhibition of biofilm formation, ranging from 15% to 80%, with the strongest effects observed against S. aureus and C. albicans. Citrus EOs inhibited the expression of several genes associated with bacterial energy metabolism, the tricarboxylic acid cycle, cell membrane proteins, and DNA metabolism. Certain genes were significantly upregulated, whereas others remained relatively unchanged.
Conclusion: Collectively, the achieved results support the possible therapeutic applications of the EOs from C. meyeri, C. paradise, and C. sinensis, and their combinations to be used as antimicrobial or anticancer agents.