Tartary buckwheat-derived exosome-like nanovesicles against starch digestion and their interaction mechanism

Abstract

This study aims to reveal the effects of Tartary buckwheat-derived exosome-like nanovesicles (TB-ELNs) on starch digestion by ultrasound-assisted treatment. TB-ELNs displayed round- or cup-shaped structures with an average diameter of ∼128 nm and zeta potential of −7.2 mV, and can maintain integrity during they pass through the gastrointestinal tract (GIT). TB-ELNs assisted by ultrasonic treatment can significantly suppress the rate of starch digestion, and increase the proportion of resistance starch (RS). The mechanical studies suggested that TB-ELNs initially showed a tendency to bind starch molecules via hydrogen bonds. After ultrasonic treatment, TB-ELNs induced a loose and porous gel matrix while increased the short-range ordered structures of the starch. This change in starch structure allows for the formation of V-type complex and lowers the accessibility of starch molecules to water and digestive enzymes. Additionally, TB-ELNs can competitively bind starch molecules and inhibit the activity of α-amylase and α-glucosidase, as evidenced by inhibition kinetics and fluorescence quenching experiments. Conclusively, TB-ELNs assisted by ultrasonic treatment show a high possibility to be developed as a promising strategy to modulate starch structures and its digestive behaviors.