Encompassment of isoeugenol in 2-hydroxypropyl-β-cyclodextrin using ultrasonication: Characterization, antioxidant and antibacterial activities

Isoeugenol is a natural dual antioxidant/prooxidant. In this research, the inclusion complex (IC) of isoeugenol with 2-hydroxypropyl- β -cyclodextrin (HP β CD) was prepared via the ultrasound (US) method. The US assisted isoeugenol/HP β CD-IC was investigated by various characterization techniques such as UV–Vis absorption, fluorescence, powder X-ray diffraction, Fourier transform infrared spectroscopy , thermal gravimetric analysis and differential scanning calorimetry . Absorption, fluorescence and infrared studies indicated that the alkyl chain of isoeugenol was deeply included in the HP β CD cavity. Through determinations of phase solubility and water solubility studies, significant enhancement of isoeugenol water solubility was confirmed after IC formation with the HP β CD. Thermal data proved that the IC formation significantly enhanced the thermal stability of isoeugenol. Antioxidant test results indicated that isoeugenol/HP β CD-IC exhibited better antioxidant activity than free isoeugenol due to its solubility enhancement. Furthermore, the isoeugenol/HP β CD-IC showed higher antibacterial activity of 96 ± 0.2% and 97 ± 0.5% against Staphylococcus aureus and Escherichia coli bacteria, respectively.