Organogels as a Delivery System for Volatile Oils

Volatile oils exhibit numerous biological activities including antimicrobial, wound-healing, and antioxidant. The domestic and medical use of these oils is, however, limited by their volatility, hydrophobic nature, and susceptibility to degradation reactions in the presence of air, light, and moisture. Here, we describe a three-dimensional (3D) structured organogel system composed of a polymeric matrix (organogelator) and three volatile oils - linalool, citral, or Mentha arvensis oil - serving as the organic phase. Increasing organogelator concentrations led to an increase in both the storage moduli and the loss moduli attributable to a higher degree of interaction between adjacent polymeric chains. Volatile oils were released into the head compartment in a controlled manner, reaching a plateau within 2 h. The antifungal activity of the various organogels against the common dermatophyte Theridion rubrum was evaluated in vitro. While organogels of all sizes showed complete inhibition for citral, a dose-dependent effect was observed for linalool and mentha oil, with the largest disks displaying clear antifungal activity and the smallest ones displaying negligible activity. In a follow-up experiment on an onychomycosis model using infected horse hooves, organogels exhibited marked antifungal activity. The ability of this system to extend the shelf life of fresh food products was also demonstrated. The versatility of the gel, the simplicity of its production, and its effectiveness make this system very attractive as a delivery platform for volatile oils.