Lipoamide is a trivial name

Trivial name

In chemistry, a trivial name is a common name or vernacular name; it is a non-systematic name or non-scientific name. That is, the name is not recognised according to the rules of any formal system of nomenclature...

 for 6,8-dithiooctanoic amide. It is 6,8-dithiooctanoic acid

Lipoic acid

Lipoic acid , also known as α-lipoic acid and Alpha Lipoic Acid is an organosulfur compound derived from octanoic acid. LA contains two vicinal sulfur atoms attached via a disulfide bond and is thus considered to be oxidized...

's functional form where the carboxyl group is attached to protein

Protein

Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

 (or any other amine

Amine

Amines are organic compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are derivatives of ammonia, wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group. Important amines include amino acids, biogenic amines,...

) by an amide

Amide

In chemistry, an amide is an organic compound that contains the functional group consisting of a carbonyl group linked to a nitrogen atom . The term refers both to a class of compounds and a functional group within those compounds. The term amide also refers to deprotonated form of ammonia or an...

linkage (containing -NH₂). Sometimes lipoamide is used to refer to protein bound lipoic acid, but this can be misleading as this is technically incorrect. Lipoyl-protein or lipoyl-domain are better terms to refer to protein bound lipoic acid.

There are no reported occurrences of free lipoamide in nature.