Rosemary Essential Oil Microemulsion for Fungal Keratitis Treatment

Area of Science:

• Ophthalmology
• Pharmacology
• Natural Products Chemistry

Background:

• Ocular fungal keratitis is a severe eye infection that can lead to vision loss.
• Current treatments may have limitations, necessitating novel therapeutic approaches.
• Natural compounds offer potential for developing new anti-infective agents.

Purpose of the Study:

• To evaluate the potential of Rosmarinus officinalis (rosemary) essential oil in a microemulsion (ME) formulation for treating fungal keratitis.
• To characterize the physicochemical properties and safety of the rosemary ME.
• To assess the in vitro antifungal efficacy of the formulation against key ocular pathogens.

Main Methods:

• Rosemary essential oil was extracted and analyzed for its major compounds, with eucalyptol identified as predominant.
• A microemulsion (ME) formulation was prepared and characterized for pH, particle size, stability, and homogeneity.
• Ocular irritancy was assessed using the Hen's Egg Test-Chorioallantoic Membrane assay, and antifungal activity was determined via minimum inhibitory concentration (MIC).

Main Results:

• The rosemary essential oil extraction yielded 1.2%, with eucalyptol at 37.89%.
• The ME formulation exhibited a suitable pH (6.96), small particle size (11.35 nm), and good stability.
• The formulation was classified as non-irritant (irritation score = 1.5) and demonstrated potent antifungal activity against Candida spp., Fusarium graminearum, and Aspergillus parasiticus.

Conclusions:

• Rosemary essential oil ME is a safe and stable formulation with significant antifungal properties.
• The formulation shows potential as a novel therapeutic agent for ocular fungal keratitis.
• Further development of rosemary essential oil-based eye drops could offer a new treatment option for this sight-threatening infection.