Three Citrus flavonoids retard the digestion of starch and its working mechanisms

In this work, the effects of three Citrus flavonoids (naringin, neohesperidin and hesperidin) on -amylase catalysed starch digestion were investigated. An inhibitory kinetics experiment demonstrated that they noncompetitively inhibit the activity of -amylase with Ki values of, respectively, 25.21m, 40.26m, 40.69m. Surface plasmon resonance assay showed three Citrus flavonoids can bind with starch with K-D values of, respectively, 3.98 +/- 0.20mm, 4.92 +/- 0.15mm and 5.07 +/- 0.17mm. Scanning electron microscopy indicated they can delay the retrogradation of starch. The results of 1, 1-diphenyl-2-picryl hydrazyl radical assay indicate that the antioxidant activities of three Citrus flavonoids are significantly decreased by interacting with starch. These results illustrated three Citrus flavonoids that retard the digestion of starch not only through interaction with -amylase, but also through interaction with starch.