General structure The general structure of a<unk>  consists of a steroid molecule attached to a sugar<unk>  and an R group. The steroid nucleus consists of four fused rings to which other functional groups such as methyl, hydroxyl, and aldehyde groups can be attached to influence the overall molecule's biological activity.<unk> s also vary in the groups attached at either end of the steroid. Specifically, different sugar groups attached at the sugar end of the steroid can alter the molecule's solubility and kinetics; however, the lactone moiety at the R group end only serves a structural function. In particular, the structure of the ring attached at the R end of the molecule allows it to be classified as either a cardenolide or bufadienolide. Cardenolides differ from bufadienolides due to the presence of an “enolide,” a five-membered ring with a single double bond, at the lactone end. Bufadienolides, on the other hand, contain a “dienolide,” a six-membered ring with two double bonds, at the lactone end. While compounds of both groups can be used to influence the<unk>  output of the heart, cardenolides are more commonly used medicinally, primarily due to the widespread availability of the plants from which they are derived. Classification<unk> s can be more specifically categorized based on the plant they are derived from, as in the following list. For example, cardenolides have been primarily derived from the foxglove plants Digitalis purpurea and Digitalis lanata, while bufadienolides have been derived from the venom of the cane toad Bufo marinus, from which they receive the “bufo” portion of their name. Below is a list of organisms from which<unk> s can be derived.Example of the chemical structure of oleandrin, a potent toxic<unk>  extracted from the Oleander bush. Plant cardenolides * Convallaria majalis (Lily of the Valley): convallotoxin * Antiaris toxicaria (upas tree): antiarin * Strophanthus kombe (Strophanthus vine): ouabain (g-strophanthin) and other strophanthins * Digitalis lanata and Digitalis purpurea (Woolly and purple foxglove): digoxin, digitoxin * Nerium oleander (oleander tree): oleandrin * Asclepias sp. (milkweed): oleandrin * Adonis vernalis (Spring pheasant's eye): adonitoxin * Kalanchoe daigremontiana and other Kalanchoe species: daigremontianin * Erysimum cheiranthoides (wormseed wallflower) and other Erysimum species * Cerbera manghas (suicide tree): cerberin Other cardenolides * some species of Chrysolina beetles, including Chrysolina coerulans, have<unk> s (including Xylose) in their defensive glands. Bufadienolides * Leonurus<unk> a (motherwort): scillarenin * Drimia maritima (squill): proscillaridine A * Bufo marinus (cane toad): various bufadienolides * Kalanchoe daigremontiana and other Kalanchoe species: daigremontianin and others *Helleborus spp. (hellebore)
Cardiac glycoside
Phytosteroid
Insulin analog
Glucocorticoid
Steroid ester
Eoxin
Clofibride
Xenohormone