Background and Objectives: The rising prevalence of antibiotic resistance and biofilm-associated infections poses significant challenges in clinical settings. This study investigates the antimicrobial and anti-adhesive properties of oleuropein, a compound derived from olive leaves, against Candida albicans and Staphylococcus aureus. Materials and Methods: This study was conducted on Candida albicans (fluconazole-resistant/susceptible) and Staphylococcus aureus (methicillin-resistant/susceptible). The antifungal, antibacterial, anti-adhesion, and cell surface hydrophobicity (CSH) effects of oleuropein were evaluated. The impact of oleuropein on germ tube formation (GTF) in C. albicans was assessed. Finally, the toxicity of oleuropein was evaluated in zebrafish embryos. Results: Oleuropein exhibited MIC values of 10 mg/ml for C. albicans and 5 mg/ml for S. aureus. It significantly (P< 0.05) reduced the adhesion of both microorganisms in a dose-dependent manner, with inhibition percentages of 78.43% and 75.91% for C. albicans and S. aureus, respectively. Additionally, oleuropein reduced the CSH of C. albicans, indicating its potential to interfere with adhesion mechanisms. In addition, oleuropein exhibited inhibition of GTF in C. albicans. Conclusion: Oleuropein demonstrates significant antimicrobial and anti-adhesive properties against C. albicans and S. aureus, indicating its potential as a therapeutic agent for preventing biofilm-related infections. However, careful dosage management is crucial due to its observed toxicity at higher concentrations.
