What does aglycon mean?
An aglycon is the non-sugar portion of a glycoside, the class of natural compounds in which a sugar molecule is bonded to a second structural unit. When chemists hydrolyze a glycoside — breaking the bond with water, acid, or an enzyme — the sugar is released and the remaining fragment is the aglycon (also spelled aglycone). This fragment frequently carries the biological activity that made the original glycoside interesting: in plant-derived medicines and foods, the aglycon is often the pharmacologically active core, as with quercetin in many flavonoid glycosides or the steroid genins of cardiac drugs like digoxin. The term appears almost exclusively in chemistry, biochemistry, pharmacy, and nutrition research, and it is essential vocabulary for anyone reading literature on plant secondary metabolites, herbal medicine, or drug metabolism, where distinguishing the intact glycoside from its aglycon can determine whether a compound is absorbed, how it behaves, and what effect it ultimately produces.
nounThe non-sugar portion of a glycoside, remaining after the sugar component has been removed by hydrolysis. It is typically responsible for the biological or pharmacological activity of the compound.
- The non-sugar residue of a glycoside left after hydrolysis, usually bearing the compound's characteristic biological activity.
"Hydrolysis of the glycoside released the aglycon, which proved to be the active therapeutic agent."
"Quercetin is the aglycon common to many flavonoid glycosides found in onions and berries."
"Enzymatic hydrolysis of digitoxin yields the aglycon digitoxigenin along with several sugar residues."
The plural follows standard English noun formation; "aglycones" appears where the variant spelling is used.
"Both aglycons exhibited antioxidant activity in vitro."
Strip the sugar off a glycoside and what's left — the aglycon — is often the part that actually does the medicinal work.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of aglycon
The word combines the Greek prefix a- meaning "not" or "without" with glykys, the Greek word for "sweet," reflecting the fact that the aglycon is the portion of a glycoside that lacks the sweet-tasting sugar. It arose alongside "glycoside" in nineteenth-century organic chemistry as scientists decomposed plant glycosides into their sugar and non-sugar components. Its Greek root also underlies related chemical terms such as glucose, glycogen, and glycoside itself.
Related word forms
How aglycon is actually used
"Aglycon" is a technical term confined to chemistry, biochemistry, and pharmacology; it is rarely encountered outside scientific literature. The variant spelling "aglycone" is equally common in British usage, and related terms such as "genin" are used for specific classes (e.g., cardiac genins).
Easily confused with aglycon
A glycoside is the complete molecule of sugar plus non-sugar part, whereas the aglycon is only that non-sugar portion once the sugar is cleaved off.