Evaluation of antimicrobial and immunomodulatory activities of Eugenol isolated from Syzygium aromaticum in a rat model

Objectives The increasing resistance of human infections to pharmaceutical treatments represents a critical global health challenge. Traditional herbs may complement modern antibacterial strategies. This study investigates the antimicrobial, antioxidant, and immunomodulatory properties of Eugenol extracted from Syzygium aromaticum . Methods The essential oil was achieved through hydro distillation and analyzed using HPLC. Antioxidant capabilities were assessed using the DPPH radical scavenging assay and reducing power. MTT assays revealed the viability percentages of A549 and MRC5 cell lines after 48 h of exposure to methanolic extract and valerianic acid. Minimum inhibitory concentration (MIC) and broth microdilution methods were utilized to test antibiotic activity against Staphylococcus aureus , Escherichia coli , and Candida albicans . Finally, the essential oil (average concentration 13.1 % ± 0.23, with major components Eugenol, β-caryophyllene, and Eugenol Acetate) was orally administered to rats for 14 days. In vivo safety and immunomodulatory effects were assessed through histopathological, hematological, and hepatic enzyme analyses, as well as cytokine profiling. Results The essential oil, rich in Eugenol, β-caryophyllene, and Eugenol acetate, demonstrated strong antioxidant activity. It exhibited significant antimicrobial effects at concentrations≥5 mg/mL, with inhibition zones comparable to standard antibiotics. Cytotoxicity remained low, and in vivo analysis revealed no adverse effects. The extract also increased IFN-γ and IL-4 levels, indicating immunomodulatory potential. Conclusions The study indicated an immunomodulatory impact by increasing IFN-γ and IL-4 levels, with no negative effects on hepatic enzymes, hematological parameters, or histopathology. In summary, this research demonstrates that Eugenol, even at low concentrations, exhibits promising antioxidant and antimicrobial activities against common pathogens.