Abstract: In order to investigate the interaction between aloe emodin and α-glucosidase, enzyme kinetics, ultraviolet (UV) spectroscopy, infrared (IR) spectroscopy and fluorescence spectroscopy were employed to investigate the inhibitory mechanism of aloe emodin on α-glucosidase and the synergistic effect of aloe emodin in combination with acarbose was also investigated in this study. The results showed that aloe emodin had better inhibitory effect on α-glucosidase as both a non-competitive and anti-competitive inhibitor when compared with acarbose. The results of UV spectroscopy indicated that a new complex was formed through the interaction between aloe emodin and α-glucosidase. The characteristic vibrations of amide groups in the IR spectra indicated that the structural conformation of α-glucosidase changed with the addition of aloe emodin. The results of fluorescence quenching experiments showed that the endogenous fluorescence of α-glucosidase was statically quenched by aloe emodin. In addition, it was also found that aloe emodin combined with acarbose had a synergistic inhibitory effect on α-glucosidase activity. This study provides an experimental basis for the future application of aloe emodin in health foods for regulating blood glucose.

Key words: aloe emodin; α-glucosidase; inhibitory mechanism; synergistic inhibition; spectral analysis