Chemical Composition and Anti-Lung Cancer Activities of Melaleuca quinquenervia Leaf Essential Oil: Integrating Gas Chromatography–Mass Spectrometry (GC/MS) Profiling, Network Pharmacology, and Molecular Docking

<b>Background/Objectives:</b> This study investigates the phytochemical composition and anticancer activity of <i>Melaleuca quinquenervia</i> leaf essential oil (MQLEO) from Egypt. <b>Methods:</b> Chemical profiling was performed using GC/MS. Anticancer activity was assessed through cytotoxicity screening against multiple cancer cell lines, with a subsequent evaluation of cell migration, apoptosis, and cell cycle analysis on the most sensitive line (A549). Network pharmacology and molecular docking analyses were employed to identify potential molecular targets and pathways. <b>Results:</b> GC/MS analysis revealed a unique profile dominated by 1,8-cineole (31.57%), α-pinene isomers (both 1R and 1S forms, collectively 21.26%), and sesquiterpene alcohols (viridiflorol: 13.65%; ledol: 4.55%). These results diverge from prior studies, showing a 25.63% decrease in 1,8-cineole and no detectable α-terpineol, suggesting environmental, genetic, or methodological impacts on biosynthesis. In vitro tests revealed selective cytotoxicity against A549 lung cancer cells (IC₅₀ = 18.09 μg/mL; selectivity index = 4.30), meeting NCI criteria. Staurosporine was used as a positive control to validate the assays, confirming the reliability of the methods. MQLEO also inhibited cell migration (62-68% wound closure reduction) and induced apoptosis (24.32% vs. 0.7% in controls). Cell cycle arrest at the G₀-G₁ phase implicated cyclin-dependent kinase regulation. Network pharmacology identified ESR1, CASP3, PPARG, and PTGS2 as key targets, with MQLEO components engaging apoptosis, inflammation (TNF, IL-17), and estrogen pathways. <b>Conclusions:</b> MQLEO demonstrates promising anticancer activity through multiple mechanisms including apoptosis induction, cell cycle arrest, and migration inhibition. The multi-target activity profile highlights its potential as a therapeutic candidate for lung cancer, warranting further in vivo validation and pharmacokinetic studies to advance clinical translation.