Green preparation of holocellulose nanocrystals from burdock and their inhibitory effects against α-amylase and α-glucosidase

Abstract

In this work, holocellulose nanocrystals (hCNCs) were isolated from burdock insoluble dietary fiber (IDF) by enzymatic hydrolysis and ultrasonic treatment and their inhibitory effects against α-amylase and α-glucosidase were investigated. The hydrodynamic diameter of hCNCs decreased from about 600 to 200 nm with increasing sonication time, accompanied by an improvement in cellulose and glucose contents. Steady-state fluorescence studies suggested that static complexes were formed between hCNCs and α-amylase or α-glucosidase via a spontaneous and endothermic approach, which was driven by both hydrophobic interactions and hydrogen bonding. The median inhibitory concentration (IC₅₀) values of hCNCs against the tested enzymes were positively correlated with their size, and non-competitive and mixed types of inhibition were detected using the Lineweaver–Burk plots. During the simulated digestion, the inclusion of burdock hCNCs obviously retarded the starch hydrolysis in both dose- and size-dependent manners, suggesting their potential in blocking the postprandial serum glucose upsurge.