Polymeric Nanocapsules Containing Fennel Essential Oil: Their Preparation, Physicochemical Characterization, Stability over Time and in Simulated Gastrointestinal Conditions

Plant essential oils, a source of biologically active compounds, represent a promisingsegment in the pharmaceutical market. However, their volatility, hydrophobicity, poor stability,and low toxicity limit direct use in pharmaceutical-related applications. Nanoencapsulation is atechnique that allows overcoming these obstacles by improving bioaccessibility and bioavailability.Nanocapsules (NCs) based on biodegradable and biocompatible poly(#-caprolactone) containingFoeniculum vulgare Mill. essential oil (FEO), known for its biological activities, were successfullyprepared by interfacial deposition of the preformed polymer method. The composition of FEO (transanetholechemotype) was determined by gas chromatography analyses. The FEO presence inside theNCs was confirmed by nuclear magnetic resonance experiments. The FEO-NCs showed nanometersize (210 nm), low polydispersity index (0.10), negative zeta potential (?15 mV), non-Newtonianrheological behavior, and high efficiency of encapsulation (93%). Moreover, parameters such asFEO-NC particle size, bioactive compound retention, and FEO composition were monitored for30 days at storage temperatures of 4 and 40 C, confirming the robustness of the nanosystem. Finally,FEO-NCs were resistant to the simulated gastric digestion and showed an effective bioaccessibility of29% in simulated intestinal digestion. Based on the results obtained, this FEO-NC nanosystem couldfind interesting applications in the nutraceutical and pharmaceutical sectors.