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 modification of the everted intestinal sac technique was utilized to study the transport of the cyanogenic glycoside amygdalin (D-mandelonitrile beta-D-gentiobioside) and its metabolite D-mandelontrile beta-D-glucoside (prunasin). Everted sacs of rat jejunum and ileum were bathed in isotonic oxygenated sodium chloride-potassium phosphate buffer containing 2.8 microCi D-[(3)H]-mannose and 0.187 microCi 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) significantly 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 influx, indicating that a fraction of the transport is carrier-mediated. Treatment with amygdalin did not significantly 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 influx of D-[(14)C]-glucose without affecting D-[(3)H]-mannose values. This is consistent with the reports finding that glycoside absorption may be mediated by SGLT1.
Wagner
Brent
B
Division of Nephrology, Department of Medicine, South Texas Veterans Health Care System University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, MC 7882, San Antonio, TX 78229-3900, USA. bwagner@texas.net
Galey
William R
WR
D000678:Amygdalin / Q000493:pharmacokinetics*; D000818:Animals; D001692:Biological Transport; D005260:Female; D006601:Hexoses / Q000378:metabolism*; D007408:Intestinal Absorption; D009570:Nitriles / Q000493:pharmacokinetics*; D051381:Rats; D020318:Rats, Long-Evans; D013997:Time Factors
D006601:Hexoses; D009570:Nitriles; C019063:prunasin; D000678:Amygdalin