No abstract

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.

No abstract

Alliums have been grown for many centuries for their characteristic, pungent flavor and medicinal properties. The present review, which includes references published up to the middle of 1984, is primarily concerned with the chemical composition, flavor, and physiological properties of these crops, their extracts, and processed products. Special emphasis is placed upon the relationship between the organoleptically and biologically active components of onion and garlic. Following a brief historical introduction, current production of commercially important alliums is described and their botanical origins and interrelationships are explained. Following consideration of the major economic diseases and pests of alliums, the agronomic, husbandry, and practices associated with their cultivation are described, particular emphasis being placed upon the storage and processing of onion and garlic. The detailed, overall chemical composition and nutritional value of members of the genus Allium are presented in Section 7; after an outline of the origin and nature of flavor components and precursors, the flavor volatiles of individual members are presented. The effects of agronomic, environmental, and processing practices on chemical and flavor content and quality are considered in Section 9. The following section deals critically with the human and animal studies which have been conducted into the medical and therapeutic properties of alliums, emphasis being placed upon the studies into the antiatherosclerotic effect of onion and garlic and their essential oils. After a study of antimicrobial properties of alliums and their effects on insects and animals, an overview is presented which highlights unexplored or inadequately studied areas and suggests rewarding areas for future research.