Antioxidant activity of vitamin E enhanced by cyclodextrin inclusion complex

Purpose The study aims to find potential method to enhance the stability and antioxidant activity of vitamins. Design/methodology/approach Vitamin E (VE) and β -cyclodextrin (CD) were used to prepare the VE- β -CD inclusion complex via a solution method. The yielded VE- β -CD obtained from optimal experimental conditions was characterized. The mechanism of complex formation and the properties of the complex was investigated by steady-state and time-resolved fluorescence techniques. The antioxidant activity of VE- β -CD was evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and compared with pure VE. Findings Three experimental factors – reaction temperature ( T ), molar ratio of VE to β -CD (rm) and inclusion time ( t ) – were studied for the preparation of VE- β -CD. At experimental conditions of T = 60°C, rm = 1:3 and t = 3 h, a maximum inclusion rate of VE (78.62%) was obtained. The Fourier-transform infrared spectroscopy (FTIR) shows that VE molecule was physically encapsulated by β -CD in the yielded product. Subsequentially, the steady-state fluorescence intensity of VE was found to increase upon encapsulation by β -CD due to the hindrance of fluorescence quenching of VE molecules inside the hydrophobic cavity of β -CD, and an inclusion constant K was determined to equal 3.58 × 103 L/mol from the fluorescence results. The fluorescent observation was confirmed by time-resolved fluorescence experiment as the lifetime of VE increased with an increase in β -CD concentration. Originality/value The ability of removing radicals by VE was significantly enhanced after the formation of inclusion complex with β -CD

Analytical Chemistry (journal) · Antioxidant · Aqueous solution · Chromatography · Cyclodextrin · DPPH · Fluorescence · Fluorescence spectroscopy · Fourier transform infrared spectroscopy · Molecule · Nuclear chemistry · Photochemistry · Physical chemistry · Stability constants of complexes · Vitamin C · Antioxidant Activity and Oxidative Stress · Biochemistry · Chemical Engineering · Chemistry · Free Radicals and Antioxidants · Organic Chemistry · Protein Interaction Studies and Fluorescence Analysis