Supramolecular encapsulation of eugenol with acyclic cucurbit[n]urils: Enhancing water solubility and in vitro antioxidant activity

In recent years, consumer demand for healthy foods containing natural food additives has increased. Eugenol (EUG) is an essential oil popular as a natural antiseptic. However, its limited water solubility, high volatility, strong odor, and fragile stability hinder its application and storage in the field of food preservation. To address these limitations and unleash the potential of EUG in food preservation, this study utilized acyclic cucurbit[n]urils (ACBs) M1 and M2 as molecular containers to encapsulate EUG to overcome the challenges associated with EUG in food preservation and improve its freshness preservation effect. The nature and behavior of the inclusion complex were confirmed by techniques such as Nuclear magnetic resonance of hydrogen (¹H NMR), 2D Rotating frame Overhauser effect spectroscopy (2D-ROESY), Field emission scanning electron microscopy (SEM-FEG), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Thermogravimetric analysis (TGA), and Differential scanning calorimetry (DSC). In addition, the in vitro antioxidant capacity and antibacterial activity of the host-guest inclusion complexes were also studied. The results demonstrate that a stable complex is formed between ACBs and EUG, and the water solubility of the M1/EUG and M2/EUG complexes is significantly improved after encapsulation. These two complexes maintained the better antioxidant and antibacterial activity of EUG. This study provides a promising strategy for the application of EUG as a food additive in food preservation.