FORMULATION DESIGN AND PHYSICOCHEMICAL STABILITY CHARACTERIZATION OF NANOEMULSIONS OF NETTLE (URTICA DIOICA) ESSENTIAL OIL USING A MODEL-BASED METHODOLOGY

Response surface methodology was employed to evaluate the effects of the formulation main components, such as Tween 80 emulsifier concentration (T80, 0.41-0.69% w/w), and ratio of canola oil to nettle essential oil (CO/NEO, 5.93-20.07 w/w) on the physicochemical stability characteristics of NEO nanoemulsions prepared by ultrasound-assisted emulsification. The droplet growth ratio (DGR), volume-weighted mean diameter (D-43) of the droplets and their polydispersity index (span), peroxide value (PV), and 1,1-Diphenyl-2-picrylhydrazyl (DPPH center dot) antiradical efficiency (AE) were analyzed. Analytical gas chromatographymass spectrometry showed that hexahydrofarnesyl acetone, neophytadiene, beta-ionone and phytol were the most dominant constituents of NEOs extracted by hydrodistillation process. An increase in T80 content significantly reduced the response variables. Applying desirability function technique for the second-order polynomial models revealed the minimum DGR (0.11), D43 (134.1 nm), span (0.38) and PV (0.85 meq O-2/kg oil), and the maximum AE (0.224 x 10(-3)) could be achieved at T80 of 0.57% w/w and CO/NEO of 8.0 w/w.