Cineole-containing nanoemulsion: Development, stability, and antibacterial activity.

Area of Science:

• Pharmaceutical Sciences
• Materials Science
• Microbiology

Background:

• 1,8-cineole, a monoterpene, possesses flavor, fragrance, and bioactive properties, including bactericidal and fungicidal activities.
• Low aqueous solubility and stability limit the efficacy of 1,8-cineole.
• Nanoemulsions (NEs) offer a promising delivery system to overcome these limitations.

Purpose of the Study:

• To develop and characterize nanoemulsion formulations containing 1,8-cineole.
• To assess the stability and antibacterial activity of the developed nanoemulsions.

Main Methods:

• Nanoemulsions were prepared using a spontaneous emulsification method.
• Formulations were characterized by droplet size, polydispersity index (PdI), and zeta potential.
• Stability was assessed using analytical centrifugation; antibacterial activity was evaluated against Gram-positive strains.

Main Results:

• The optimized F1 nanoemulsion exhibited a droplet size of ~100 nm, PdI <0.2, and a zeta potential of -35 mV.
• F1 and F5 formulations demonstrated high stability with low droplet migration velocities.
• F1 nanoemulsion showed >80% incorporation efficiency and enhanced antibacterial activity against Staphylococcus aureus, Enterococcus faecalis, and Streptococcus pyogenes.

Conclusions:

• A stable nanoemulsion of 1,8-cineole was successfully developed using a low-energy emulsification method.
• The nanoemulsion formulation significantly improved the antibacterial efficacy of 1,8-cineole against key Gram-positive pathogens.
• This approach offers a viable strategy for enhancing the therapeutic potential of 1,8-cineole.