Kinetic analysis of hexose transport to determine the mechanism of amygdalin and prunasin absorption in the intestine

Evidence is accumulating that glucose‐conjugated compounds may be carried across the gut mucosa via the epithelial sodium‐dependent monosaccharide transporter SGLT1. A modication of the everted intestinal sac technique was utilized to study the transport of the cyanogenic glycoside amygdalin ( d ‐mandelonitrile β ‐ d ‐gentiobioside) and its metabolite d ‐mandelontrile β ‐ d ‐glucoside (prunasin). Everted sacs of rat jejunum and ileum were bathed in isotonic oxygenated sodium chloride–potassium phosphate buffer containing 2.8 µCi d ‐[ 3 H]‐mannose and 0.187 µCi d ‐[ 14 C]‐glucose. For treatment groups, buffers contained phloridzin, galactose, amygdalin or prunasin. The rate constant ( k ) for the transport process was calculated. Compared with the control ( n = 33), phloridzin ( n = 25) signicantly reduced the rate constants of both d ‐[ 14 C]‐glucose and d ‐[ 3 H]‐mannose. Substitution of sodium with choline and incremental galactose treatments similarly reduced d ‐[ 14 C]‐glucose inux, indicating that a fraction of the transport is carrier‐mediated. Treatment with amygdalin did not signicantly affect the rate constants of d ‐[ 14 C]‐glucose or d ‐[ 3 H]‐mannose transport. However, treatment with 1 mM prunasin ( n = 16) did reduce the inux of d ‐[ 14 C]‐glucose without affecting d ‐[ 3 H]‐mannose values. This is consistent with the reports nding that glycoside absorption may be mediated by SGLT1. Copyright © 2003 John Wiley & Sons, Ltd.