Saponins disruption

Saponins disrupt red blood cells and may produce diarrhea and vomiting. They may also have a beneficial effect by enmplexing with cholesterol and thus lowering serum cholesterol levels. In humans, intestinal microflora seem to either destroy saponins or inactivate them in small concentrations. 

There has been considerable discussion regarding the mode of action of the sea cucumber and starfish saponins. Both the triterpene and steroidal glycosides inhibit both Na/K ATPase and Ca/Mg ATPase 06) possibly as a result of their aglycone structures. However, their detergent properties cause membrane disruption which will influence the activity of membrane-bound enzymes such as the ATPases. In investigating the actions of saponins on multilamellar liposomes, it was found that cholesterol serves as the binding site for such saponins and that cholesterol-free lip-somes are not lysed by saponins 107). 

Many of the toxins obtained from coelenterates and echinoderms, because of their hemolytic or cytotoxic actions, are assumed to have a general disruptive action on cell membranes. However, since many of these toxins are capable of forming pores or channels in the plasma membrane of cells, their cytolytic actions may be a result of this highly selective action. On the other hand, the saponins from starfish and sea cucumbers have a direct lytic action as a result of their detergent action on the integrity of cells. 

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]...

Surfactants Sodium lauryl sulfate, saponin, polyoxyethylene-9-lauryl ether, polyoxyethylene-20-lauryl ether, alkylmaltosides such as tetradecylmaltoside, dodecylmaltoside, and decylmaltoside Membrane disruption... 

This suggests that the disruption of phar-macomechanical coupling in saponin-treated smooth muscle is due to disruption of the coupling between surface-membrane receptors and their G proteins while the G protein effector cascade appears to be functional. 

Insufficient volatility and thermal stability are the biggest challenges in the application of gas chromatography for the analysis of steroids. The development of gas chromatography (GC) methods for steroids analysis should take in consideration thermal stability, the derivatization step to increase volatility, the stationary phase, and the detector. Several GC methods have been summarized for the analysis of various steroids including anabolic steroids, brassinosteroids, corticoids, estrogen, endocrine-disrupting chemicals, neurosteroids, sterols, steroid saponins, and steroid alkaloids. 

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