New Approach to Prepare Willow Bark Extract-Lipid Based Nanosystems with Enhanced Antioxidant Activity

In this study the conventional oils used for lipid nanocarriers (NLCs) synthesis were replaced by high concentration of fish oils (e.g., fish oil concentrated in omega-3 fatty acids, fish oil enriched in omega-3 and omega-6 fatty acids and salmon oil), in order to produce appropriate lipid based nanosystems able to entrap willow bark extract (WBE). Formulation factors such as the nature of the fish oil, glycerol content and WBE loading were evaluated to produce optimum lipid based nanosystems with suitable physical stability and enhanced antioxidant activity. The synthesized WBE-NLC showed spherical and homogeneous particles and average diameters in the range of 200-250 nm, as determined by TEM measurements. The electrokinetic potentials were negative for all free- and WBE-loaded NLCs, with values between -29.1 ÷ - 35.8 mV, which reveal an excellent physical stability. By scanning calorimetry measurements it has been shown that the lipid crystallization and melting behavior of NLCs before and after loading with WBE were no significantly influenced by the type of fish oil used and only in a few NLCs formulations an obvious perturbation of lipid network have been detected. The chemiluminescence technique has been used to assess the effect of fish oil type on the in vitro antioxidant activity of WBE-NLCs. Ability of WBE entrapped within NLCs to scavange the free radicals was greater than for native WBE and fish oils. The difference between the antioxidant activity of WBE-NLC (98%) and those of pure WBE (AA% = 77.2) and fish oil (AA% = 83.7), may be explained by the occurrence of a synergistic effect between the components of lipid nanocarriers.