Dual-Action Antibacterial Agents Targeting Biofilm Reduction and Membrane Disruption in Staphylococcus aureus

Antimicrobial resistance in Staphylococcus aureus is a serious global health problem as the organism rapidly develops resistance against widely used antibiotics. This study sought to investigate the antibacterial and antibiofilm properties of γ-Tocopherol, a natural compound from Ocimum gratissimum, as well as its synergism with 5-hydroxymethylfurfural (5-HMF) against S. aureus. The antibacterial activities and minimum inhibitory concentrations of the compounds were determined using agar diffusion and microbroth dilution methods, respectively. Biofilm reduction was evaluated using 2,3,5-triphenyltetrazolium chloride (TTC) assay and membrane integrity was evaluated using the crystal violet microtiter plate assay and the ion leakage assay. The results showed that γ-Tocopherol and the combination (T5) inhibited bacterial growth at 2 mg/mL and were bactericidal at 16 mg/mL, respectively. The nucleotide and potassium ion leakage assays indicated plasma membrane rupture, as observed upon T5 treatment. The effect of T5 on the bacteria was further confirmed and visualized by scanning electron microscopy. In the biofilm inhibition assay, γ-Tocopherol and T5 showed promising ability to reduce biofilm formation by S. aureus. At MIC, γ-Tocopherol achieved a % inhibition of 68.81%, and T5 achieved 72.45%. By investigating the dual action of both compounds, this study provided valuable insights into their potential usage in antibacterial therapy. The study also demonstrated the importance of exploring bioactive compounds from medicinal plants as potential antimicrobial agents.