Butyr

Butyr is a naming stem used in chemistry and biochemistry to indicate a four‑carbon skeleton or derivatives derived from butane. The term traces its roots to the word butter, via the French beurre, and appears in several chemical names such as butyric acid and related compounds.

In chemical nomenclature, butyro- or butyr- denotes a C4 framework. It appears in compounds including butyric acid (butanoic acid), butyraldehyde, and butyrates, as well as amides and esters derived from these acids.

In biology and medicine, butyr or butyrate refers to the salt or ester of butyric acid. Butyrate is a short-chain fatty acid produced by anaerobic bacteria during the fermentation of dietary fiber in the colon. It serves as a primary energy source for colonocytes and is studied for anti-inflammatory and epigenetic effects, including inhibition of histone deacetylases.

In nutrition and food science, butyric acid is associated with the odor of rancid butter; it occurs naturally in small amounts in dairy products and is also produced in the gut by microbial metabolism.

Note: “Butyr” should not be confused with “butyl,” the four‑carbon alkyl group used in organic chemistry. The prefix butyro- typically signals carboxylic acid derivatives and related compounds, whereas butyl denotes a hydrocarbon substituent.

See also: butanoic acid, butyrate, short-chain fatty acids, butyl.