Preparation, Optimization, and Characterization of Inclusion Complexes of Cinnamomum longepaniculatum Essential Oil in β-Cyclodextrin

Abstract

Cinnamomum longepaniculatum essential oil (CLEO) possesses antibacterial, anti-inflammatory, and antioxidant activities. However, CLEO shows volatilization and poor solubility, which limits its application field. In this research, inclusion complexes of β-cyclodextrin (β-CD) with CLEO were produced, and its physicochemical properties were characterized. Response surface methodology was used to obtain optimum preparation conditions. A statistical model was generated to define the interactions among the selected variables. Results show that the optimal conditions were an H2O/β-CD ratio of 9.6:1 and a β-CD/CLEO ratio of 8:1, with the stirring temperature of 20 °C for the maximal encapsulation efficiency values. The physicochemical properties of CLEO/β-CD inclusion complexes (CLEO/β-CD-IC) were investigated. Fourier transform infrared spectroscopy showed that correlative characteristic bands of CLEO disappeared in the inclusion complex. X-ray diffraction presented different sharp peaks at the diffraction angle of CLEO/β-CD-IC. The thermogravimetric analysis demonstrated the thermal stability of CLEO was enhanced after encapsulation. Tiny aggregates with a smaller size of CLEO/β-CD-IC particles were observed by scanning electron microscopy. The comparison of β-CD, CLEO, and physical mixtures with CLEO/β-CD-IC confirmed the formation of inclusion complexes.