Steroidal glycoside

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). 

More recently, the clavulones (not specified which ones) [134] were described to have potent effects on the spontaneous beating rate of cultured myocardial cells from fetal mouse hearts. At a concentration of 0.45 pM, clavulone had positive chronotropic action on these cells however, the character of this effect clearly differed from the positive ionotropic and negative chronotropic effects of the steroid glycoside ouabain or the drug Bay K 8644. Hence, these results suggest that the clavulones may possess a new mechanism of action in this assay system. 

Steroidal glycosides, saponins CrinozoaJ Polyketide sulfates Asterozoa... 

Figure 9.14 A steroid glycoside. Digitoxenin is a cardiac-stimulating drug. It is a steroid glucoside in which a compound with a steroid structure is linked to a-D-glu-copyranose by condensation of the anomeric hydroxyl group on the carbohydrate and the alcohol group at position 5 on the steroid nucleus.

In steroidal glycosides, the sugar moiety is joined to the cyclopentanoperhy-drophenanthrene (steroid) nucleus. Steroidal glycosides include the cardeno-lides (cardiac glycosides) and saponins (sapogenic glycosides). 

History. For centuries man has recognized that rodent pests destroy his habitat, consume his food, and cause the spread of virulent diseases. Throughout the same centuries man has sought to eliminate these pests with a variety of poisons such as strychnine, arsenious oxide, and red squill - a steroidal glycoside extracted from the bulb of a lily-like plant, Urginea maritima. 

The study of marine natural products has great possibilities for new products. Thus, Paul Scheuer from Hawaii studied bioactive compounds from mollusks and other marine sources. Luigi Minale, Raffaele Riccio and Maria lorizzi from Italy, conducted a comprehensive research on marine steroidal glycosides. Joel Kashman from Tel-Aviv University investigated on the biologically active natural products from marine organisms. 

Shvets, S. A., P. K. Kintya, O. N. Gutsu, and V. 1. Grishkovets. Steroid glycosides of the seeds of Nicotiana tabacum. 11. The structures of nicotianosides C and E. Chem Nat Comp 1995 31(3) 332-335. Shinozaki, Y., T. Tobita, M. Mizutani, and T. Matsuzaki. Isolation and identification of two new diterpene glycosides from Nicotiana tabacum. Biosci Biotech Biochem 1996 60(5) 903-905. 

Kicha, A.A. Kalinovsky, A.I. Ivanchina, N.V. StMiik, V.A. (1999) New steroid glycosides from the deep-wata starfish Mediaster murrayi. J. Nat. Prod., 62, 279-82. 

Myocardial cell membrane ATPase, the enzyme present in heart muscle, is the site of action of the cardiac steroid glycosides, which have a specific action on the heart muscle. These drugs increase the force of contraction of the muscle (positive inotropic effect) as well as its conductivity and automaticity. They are also valuable in treating congestive heart failure, in which the circulatory needs of organs are no longer satisfied, and heart arrhythmias, in which the rhythm of the cardiac contractions is upset. The effect of the drug is that the force of contraction increases and the heart rate is slowed (chronotropic effect). Consequently, the cardiac output is elevated while the size of the heart decreases. 

The exterior of the myocardial enzyme, situated in the plasmalemma, is considered to be the specific binding site of cardiac steroid glycosides. It is believed that the positive inotropic effect is due to the inhibition of enzyme dephosphorylation and... 

Cardiac steroids, or cardenoUdes, are steroid glycosides. Their effect has been known since the time of the ancient Egyptians. In more recent times, the foxglove (Digitalis purpurea) and its effect were described in 1785 by William Withering, who knew of its use in folk medicine. 

Glycosides can be classified on the basis of the structural types of aglycone present in the glycoside. For example, in anthraquinone, flavonoid, iridoid, lignan or steroid glycosides, the aglycones are anthraquinone, flavonoid, iridoid, lignan or steroid, respectively. 

Periploca sepium Berge. Xiang Jia Pi (Silk vine) (root bark) Steroid glycosides, carenolide, periplocin, pregnenes(low toxicity).2933 Antirheumatic, cardiotoxic. 

Sesbinia sesbin (L.) Merrill. Indian Tian Qing (root, leaf, bark, seed)57 Saponins, triterpene glycosides, steroid glycosides, glycoalkaloids, kaempferol trisaccharide.342 343 344 Diuretic, irregular menses, externally for bug bites, antitumor. 

Steroid alkaloid glycosides Steroid glycosides Steroid saponins... 

In the biochemistry of D-fucose and its derivatives, there are larger lacunae in our knowledge. The biosynthesis of D-fucose has not been examined, so that it is not yet known how this sugar is produced in the organisms that contain it (mainly plants and some micro-organisms). In plants, it occurs especially in the form of steroid glycosides, whereas, in micro-organisms, it has been particularly located in antibiotic substances. It has not been identified in animals. 

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