Cholesterol saponins

Alternative adsorbents for cholesterol are food-grade saponins. Com-plexation of cholesterol in milk fat with saponins in aqueous solutions, followed by separation of the cholesterol-saponin complex has been shown to be technically feasible for cholesterol removal (Sundfeld et al., 1993). 

The scientific name of Chinese chives is Allium tuberosum Rottl. (Liliaceae). It is known as Jiucai in China and Nira in Japan. It is a perennial plant and both the leaves and the inflorescences are edible. It has also been used as an herbal medicine for many diseases. According to the dictionary of Chinese medicines, the leaves have been used for the treatment of abdominal pain, diarrhea, hematemesis, snakebite and asthma while the seeds are used as a tonic and aphrodisiac. In the present study, 39 compounds were isolated and identified from the ethanol extract of the seeds of Allium tuberosum. Among them, 23 are new compounds and include spirostanol saponins, furostanol saponins, cholesterol saponins and alkaloids. Their structures were identified by a combination of ESIMS, ID, and 2D-NMR (COSY, TOCSY, ROSEY, HMQC, and HMBC). The antitumor activities of some of these compounds will be discussed. 

Saponins dismpt red blood cells and may produce diarrhea and vomiting. They may also have a beneficial effect by complexing with cholesterol [57-88-5] and thus lowering semm cholesterol levels (24,25). In humans, intestinal microflora seem to either destroy saponins or inactivate them in small concentrations. 

Saponins. Although the hypocholesterolemic activity of saponins has been known since the 1950s, thek low potency and difficult purification sparked Htde interest in natural saponins as hypolipidemic agents. Synthetic steroids (292, 293) that are structurally related to saponins have been shown to lower plasma cholesterol in a variety of different species (252). Steroid (292) is designated CP-88,818 [99759-19-0]. The hypocholesterolemic agent CP-148,623 [150332-35-7] (293) is not absorbed into the systemic ckculation and does not inhibit enzymes involved in cholesterol synthesis, release, or uptake. Rather, (293) specifically inhibits cholesterol absorption into the intestinal mucosa (253). As of late 1996, CP-148,623 is in clinical trials as an agent that lowers blood concentrations of cholesterol (254). 

Goad (40) and others have extensively reviewed coelenterate and echinoderm sterols including the saponins found in starfish and sea cucumbers. Cholesterol is a common sterol in most families, except for gorgonians and zoanthids some soft corals contain polyhydroxylated sterols. The amount of variation associated with phylogeny is illustrate in the echinoderms by the fact that crinoids, ophuiroids, and echinoids contain A 5 sterols while holothuriodeans and asteroids contain A 7 sterols. Some classes contain uniquely structured sterols. 

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). 

Members of the family Amaranthaceae are known to produce ecdysteroids such as 8-ecdysone (19) and inocosterone (20). From petroleum ether extracts of Amaranthus splnosus Linn. Behari and Andhiwal (21) obtained 8-sitosterol (4), stigmasterol (3), campesterol and cholesterol. From the roots of the same species, Banerji (22) isolated two new saponins, a diglucoside and a triglucoside of o-spinasterol. More recently, Roy et al. (23)... 

Theory The assay of cholesterol is solely based on the fact that practically all 3 (3-hydroxysterols e.g., cholesterol, readily produces an insoluble molecular addition complex with pure digitonin (1 1)—a steroidal saponin isolated from either Digitalis purpurea or Digitalis lanata. The complex thus obtained is crystalline in nature, fairly stable and possesses very low solubilities. 

Lysolecithins act by dissolving cholesterol and cause massive losses of the sterol from membranes (19). Lysolecithins have been shown to cause the formation of openings 300-400 A in diameter in erythrocyte plasma membranes (20). Unlike saponins, lysolecithin membrane openings are permanent. 

Legumes Cardiovascular disease Presence of saponin which decreases cholesterol absorption from the gut... 

Allium chinense Max. A. odorum L. A. sativum L. A. tuberosum Roxb. A. uliginosum G. Don Da Suan (Garlic) (bulb) Allicin, allistatin, glucominol, neo-allicin, steroidal saponins, polysaccharides, furostanol saponins, proto-isoerubosides, diallyl sulfide.33 49 438 490-510 Antibacterial, antimutagenic, anticarcinogenesis, carminative, antiarrhythmic, lower plasma cholesterol and low-density lipoproteins, prevent thrombosis, hypotensive and vessel protective effect. 

Trigonella foenum-graecum L. Wu Ru Ba (Fenugreek) (seed) Trigonelline, saponins, flavone derivatives including vitex, saponaretin, isoorientin, vitexin-7-glucoside.33 Reduce plasma cholesterol levels, support hepatic and renal functions. 

Saponins consist of a terpenoid core (the aglycone), having oxygenated positions bound to sugar moieties (up to ten monosaccharidic units). In water they form colloidal solutions which foam on shaking and precipitate cholesterol. When saponins are near cell membranes, their interaction with cholesterol may create pore-like structures that eventually cause the membrane to burst. Hemolysis is an example of this phenomenon (i.e. the distraction of erythocyte membranes, but not hemoglobin). Occasionally, they cause hypersecretion, which could explain their expectorant activities and also their toxicity to fish. 

In general, Astragalus saponins exert a positive and direct effect on the function of heart. Alternatively, they help to treat related diseases. For instance, they inhibit the formation of lipid peroxides in the cardiac muscle or in the liver, influence the function of enzymes contained in them, decrease blood coagulation, cholesterol and sugar levels in blood, and stimulate the immunological system. They act either direct, blocking the transfer of Ca2+ ions or modulating the function of Na+-K+-ATPase, or, alternatively, help resorb other active principles [150]. 

In the intestine, saponins bind to mucosal cell membranes and change their physiology. Since the membranes of some cancer cells contain more cholesterol than do normal cells membranes [156], it is possible that saponins bind more to cancer cells and as a result induce their destruction. Since saponins are surface-active compounds that are not absorbed, their possible interaction with intestinal mucosal cell membranes must be emphasized. Because the average transit time of food is 24h, saponins can either in the intact or in the partly hydrolyzed form, remain in the intestine long enough to interact with free sterols and membrane lipids [157]. 

Saponins. Synthetic steroids that are structurally related to saponins have been shown to lower plasma cholesterol in a variety of different species. 

The cholesterol-lowering ability of saponins was first observed in the 1950s and has since been confirmed in a number of species including humans (reviewed in Oakenfull and Sidhu, 1990). Saponins have also been shown to decrease the development of arterial atherosclerosis (Koo, 1983 Malinow... 

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). 

Another possible mechanism involves the effect of saponins on micelle formation. Saponins are known to alter the size or shape of micelles (Oakenfull, 1986 Oakenfull and Sidhu, 1983), an observation that is consistent with decreased bile acid absorption (Stark and Madar, 1993) and increased fecal bile acid excretion (Malinow et al., 1981 Nakamura et al.,1999). Saponins may also directly bind bile acids (Oakenfull and Sidhu, 1989), which would presumably interfere with micelle formation and decrease cholesterol absorption. Other studies have found that saponins decrease the absorption of fat-soluble vitamins (Jenkins and Atwal, 1994) and triglycerides (Han et al., 2002 Okuda and Han, 2001), indicating decreased micelle formation. However, direct evidence showing impaired micelle formation in vivo is lacking. Moreover, Harwood et al. (1993) reported no change in bile acid absorption or interruption of the enterohepatic circulation of bile acids in hamsters fed tiqueside, despite significant reductions in cholesterol absorption. 

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