The influence of four saponins, three triterpenoid glycosides and one steroidal amine glycoside, upon intestinal transport was investigated in vitro. In the presence of Gypsophylla saponin, carrier-mediated galactose transport was inhibited, although the uptake of the passively transported L-isomer of glucose increased. The uptake of the extracellular space marker, polyethylene glycol 4000, was also higher, indicating that the saponin inhibited active transport by increasing the general permeability of the enterocytes. Gypsophylla saponin, in contact only with the mucosal surface of everted jejunal sacs, induced a rapid decline in glucose-stimulated transmural potential difference. The rate of decline increased as the saponin concentration was raised over the approximate range of 0.3 to 8 mM. Saponaria saponin and alpha-tomatine also reduced transmural potential difference, but soya saponins were much less effective. The results indicate that some saponins readily increase the permeability of the small intestinal mucosal cells, thereby inhibiting active nutrient transport, and facilitating the uptake of materials to which the gut would normally be impermeable.

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The total saponin content of various legume seeds together with their sapogenol composition have been determined. Extraction of the defatted flours was effected with methanol and subsequent acid hydrolysis yielded the soyasapogenols which were analysed using gas and thin-layer chromatography. The saponin levels ranged from M).65% for defatted seed while the major sapogenol present in these saponins was soyasapogenol B. The figures obtained are compared with those previously reported and reasons are suggested for the discrepancies.

No abstract