Bufadienolide steroids

When used at room temperature in the presence of an active platinum catalyst in an inert solvent, e.g., acetone or ethyl acetate, oxygen will oxidize nonhindered, saturated hydroxyl groups and exposed allylic alcohols. This reagent has found extensive use in sugar chemistry and is particularly suited for the selective oxidation of either 3a- or 3j -alcohols of steroids. Other hydroxyl groups on the steroid skeleton are much less sensitive to oxidation. As a result, this reaction has been used extensively in research on polyhydroxy cardiac-active principles, e.g., the cardenolides and bufadienolides, where the 3-hydroxyl group is easily oxidized without extensive oxidation or dehydration of other hydroxyl groups. The ordinarily difficult selective oxidation of the... 

Na+/K+-ATPase. Figure 2 Specific Inhibitors of Na+/K+-ATPase. (a) Endogenous cardiac glycosides identified in mammals. Substances with a 5-membered lactone at position C17 of the steroid moiety are referred to as cardenolides, those with a 6-membered lactone as bufadienolides. (b) Palytoxin (C P NsO ) produced by corals of the genus Palythoa. 

Three of the classes of compounds found from the skin of amphibians have been identified from the skin of bufonids, including Bufo marinus. These are steroids (bufadienolides), biogenic amines (catecholamines, indolylalkylamines and alkaloids) and bioactive peptides and proteins. 

This direct synthesis of steroidal pyrones should make a variety of structures related to the lucibufagins (as well as to the toad-derived bufadienolides) readily available for biological investigation for the first time. How the insects themselves manage to obtain their defensive pregnanes and steroidal pyrones remains a mystery, since insects are generally considered to lack the enzymatic machinery essential for steroid biosynthesis (19). In fact, we do not yet know whether these insect defensive steroids are produced de novo or whether they are derived... 

Although the limitations in the cases that provide good yields may appear to be very restrictive, this last example is suggestive of the potential applications of this procedure. Rather obvious possibilities that follow from this case include derivatives of the equilinin steroidal hormone system,11 and of the steroidal cardiotonic agents, e.g., the cardenolides, digitoxigenin, bufadienolides, etc.12... 

A. Bufadienolides They are C 24 steroids. Hellbrien is a bufadienolide cardiac glycoside. On hydrolysis, it yields aglycone, hellbrigenin, which is more active than hellebrin. 

Cephalostatins 14 and 158 (Figure 5) are related to cephalostatins 2 and 3 respectively by a-epoxidation at C-14 -15 dehydration of the C-9 alcohol, and hydroxylation at C-8 . Cephalostatins 14 and 15 display reduced activity, with mean panel GI50 of 100 and 68 nmolar respectively, perhaps due to the epoxide orientation - with steroidal bufadienolides, the p-epoxides are more cytotoxic. 

Various aspects of steroid biosynthesis were included in a Royal Society Symposium. The published proceedings and other reviews have dealt with cyclase enzymes,water-soluble steroids and triterpenoids, the involvement of a 14(15)- or 8(14)-double bond and its reductionin cholesterol biosynthesis, biosynthesis of sterols, steroid metabolism in insects, pregnane steroids, cardenolides, and bufadienolides. ... 

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