Evaluation of the interaction of maize fiber gum with α-amylase and α-glucosidase enzymes and its effect on enzymes inhibition activity

Maize bran is the most common by-product of maize milling process and it is mainly used as animal feed. In this study, antioxidant and anti-diabetic activities of two types of maize fiber gum, FAX (fiber with phenolic compounds) and Y (fiber without phenolic compounds), were examined. In addition, intrinsic and extrinsic fluorescence intensity was assessed to explore the inhibitory mechanism of two enzymes, α-amylase and α-glucosidase. The results revealed that FAX had the highest DPPH radical scavenging property at 39.74 ± 0.399 µmolTE/g, whereas Y had 3.73 ± 0.257 µmolTE/g. Furthermore, the ABTS cationic radical scavenging activity in FAX was 137.10 ± 2.99 µmolTE/g, whereas Y was 29.68 ± 1.17 µmolTE/g. FAX had a higher inhibition rate of porcine α-amylase enzyme activity than Y, and the difference was significant (p ˂ 0.05). FAX inhibited rat intestinal α-glucosidase activity the highest (26.15%), whereas Y had no enzyme inhibition property at the concentration used. In addition, applying different concentrations of both fibers to α-amylase and α-glucosidase enzymes resulted in a decrease in fluorescence intensity; however, this intensity was higher for FAX. Both fibers were able of inhibiting both enzymes by changing the third structure of the enzyme via non-covalent bonds. Overall, the results showed that high phenolic fiber from maize bran can be consider as a natural source of antioxidant activity and inhibition of α-amylase and α-glucosidase enzymes, and that it can be used in the production of functional foods.