Saponins glucose

Fig. 2.1 Strucnires of some common saponins. The strucnires of some of the saponins described in the text are shown, including aescin from horse chesnut, avenacin A-1 and avenacoside A from oat, and a-tomatine from tomato. The glucose molecule enclosed in square brackets in the structure of avenacoside A highlights the glucose moiety that is cleaved off by hydrolysis by glycosidases in disrupted oat leaf tissue, leading to the fungitoxic 26-desglucosyl avenacoside A. Redrawn from [94]...

Nephelium longana Camb. N. lappaceum L. Ron Yen Raw Hong Mao Dan (Rambutan) (aerial part, kernel) Glucose, sucrose, tartaric acid, vitamins A, B, saponins, tannins.49 Nutrient tonic in neurasthenia, insomnia, styptic. 

FIG. 4 Structure of representative saponins found in soybeans (triterpenoid) and eggplant (steroid). The R group represents one or more carbohydrate linkages that may contain rhamnose, xylose, arabinose, galactose, glucose, or glucuronic acid. 

Saponins appear to lower plasma LDL cholesterol concentration by interfering with cholesterol absorption. Studies in rats and monkeys fed naturally occurring saponins exhibited significant reductions in cholesterol absorption efficiency and an increase in fecal cholesterol excretion (Malinow et al., 1981 Nakamura et al., 1999 Sidhu et al., 1987). Decreased bile acid absorption and increased excretion has also been reported in animals fed saponins (Malinow et al., 1981 Nakamura et al., 1999 Stark and Madar, 1993). One possible mechanism of action for decreased cholesterol absorption is the ability of saponins to form insoluble complexes with cholesterol (Gestetner et al., 1972 Malinow et al., 1977). In an effort to isolate the specific properties of saponins, Malinow (1985) prepared a variety of synthetic saponins in which the complex carbohydrate moieties of native plant saponins were replaced with simplified carbohydrates such as glucose or cellobiose. One of these synthetic saponins, tiqueside (Pfizer, Inc.), can effectively precipitate cholesterol from micelle solutions in vitro and inhibit cholesterol absorption in a variety of animals (Harwood et al., 1993) and in humans (Harris et al., 1997). But despite ample data showing the formation of a saponin/cholesterol complex in vitro, there is essentially no definitive evidence that complexation occurs in the intestinal lumen (Morehouse et al., 1999). 

Sidhu, G.S., Upson, B., and Malinow, M.R. 1987. Effect of soy saponins and tigogenin cellobioside on intestinal uptake of cholesterol, cholate, and glucose. Nutr. Rep. Int. 35, 615-623. 

CD detection for colored derivatives might just as easily be used for structural information about the carbohydrates as well as for their analysis, but so far little attention has been given to either application. Cyclic oligomers of p-D-glucose have important supporting roles to play in analytical applications that are discussed in a later section. The union of chirality in the carbohydrate moiety of a glycoside metabolite with the unsaturation in the base in such compounds as nucleosides and nucleotides, saponins and flavones, etc., is another area that will ultimately be developed for applications of chiroptical detection methods. New and imaginative ideas are needed for the analysis of carbohydrates, and CD should be one of the favored methods. 

Gymnemic saponins Gymnema sylvestre (Asclepiadaceae) inhibited) [0.2], Insulin-stimulated Glucose TR (rat adipocyte) [0.2] [independent of AC activation (q.v.)] Glc-TR [hypoglycaemic]... 

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