Antioxidant Property and Bactericidal Activity of Linum usitatissimum Seed Essential Oil Nanoemulsion (LSEO-NE) on Staphylococcus aureus

Background: Linum usitatissimum Seed Essential Oil (LSEO) as an efficient antimicrobial compound contains various types of phytochemicals, such as lignans and phenols. Objectives: In the current study, we produced LSEO nanoemulsion (LSEO-NE) to study its antioxidant capacity and bactericidal activity against Staphylococcus aureus. Methods: The LSEO-NE was produced using the ultrasonication method and characterized by Atomic Force Microscopy (AFM), Dynamic Light Scattering (DLS), and Scanning Electron Microscopy (SEM). Then, we measured its antioxidant activity utilizing both ABTS and DPPH tests at four different LSEO-NE concentrations (200, 600, 800, and 1000 ug/mL) compared to glutathione. Finally, we evaluated its bactericidal activity on S. aureus by studying Antibiotic Susceptibility Testing (AST) using LSEO-NE-smeared discs compared to non-smeared and kanamycin discs. Results: The 67.3 nm droplets of LSEO-NE with PDI of 0.452 exhibited strong antioxidant activity, similar to glutathione, in both ABTS (IC_50 = 350 ug/mL) and DPPH (IC_50 = 235 ug/mL) tests. Moreover, the AST results revealed the significant sensitivity of S. aureus to LSEO-NE-smeared discs when compared to non-smeared and kanamycin discs. Conclusions: According to the results, LSEO-NE can be applied as a safe, natural, and effective antibiotic for bacterial infections caused by S. aureus in most organs, such as the respiratory system and skin. However, further in vivo studies are required to evaluate the LSEO-NE antibacterial efficiency against other pathogenic S. aureus strains.