A plant compound containing one or more alcohols or sugars and a biologically active compound. The sugar part is called a glycone, the other stuff is called an aglycone. The important things to remember about some glycosides is that they may pass through much of the intestinal tract, with the hydrolysis of the molecule only occurring in the brush borders of the small intestine. The result is that the bioactive part, the aglycone, is absorbed directly into the bloodstream, and is often not floating around the intestinal tract contents at all.
Quinones are irritating and even toxic when ingested, but when taken as glycosides, they are absorbed directly into the bloodstream, where they are not dangerous (in moderation), and get excreted in the urine, where they inhibit infections. Plants like Madrone, Uva Ursi, and Manzanita work in this fashion. Some plant-derived heart medicines are only safe in proper doses because they, too, are glycosides, and they can be carried safely bound to proteins in the bloodstream, whereas if the aglycone were in the free form in the gut it might be either toxic or be digested directly into an inactive form.
Compounds of a sugar attached to another molecule. When glucose is the sugar, they are called glucosides.
Any of a group of compounds that yield sugar molecules on hydrolysis. All parts of a glycoside compound may be sugar molecules, so that sucrose, raffmose, starch, and cellulose—all of which hydrolyze into sugar molecules—may all be considered to be glycosides. However, the name (glycoside) is usually applied to a compound in which part of the molecule is not a sugar. This nonsugar component is called the aglycon.
Naturally occurring substance consisting of sugars combined with nonsugars such as a flavonoid, coumarine, steroid, terpene, and so forth (aglycones).
A chemical substance that yields at least one simple sugar upon hydrolysis.
A plant product consisting of an organic molecule combined with sugar. Some very important drugs are, e.g., cardiac.
A chemical compound of a type which is formed from a simple sugar and another compound.
A compound formed by replacing the hydroxyl (-OH) group of a sugar by another group. (If the sugar is glucose the compound is known as a glucoside.) Glycosides found in plants include some pharmacologically important products (such as digitalis). Other plant glycosides are natural food toxins, present in cassava, almonds, and other plant products, and may yield hydrogen cyanide if the plant is not prepared properly before eating.
A compound of a sugar and a non-sugar unit. Glycosides are widespread throughout nature and include many important drugs such as digoxin.
A substance derived from plants that, on hydrolysis, yields a sugar and one or more additional products. Depending on the sugar formed, glycosides are designated glucosides or galactosides. Digitalis is a commonly used cardiac glycoside.
A compound resulting from the linking of sugar and a non-sugar portion called an aglycone or a genin.
One of a group of substances in plants containing a carbohydrate molecule (sugar), convertible by hydrolysis into sugar and a non-sugar component.