endocon

https://doi.org/10.1351/goldbook.15661
Portion of a conjugated metabolite that is derived from a natural product (such as a sugar, amino acid, or other organic acid) of the metabolizing organism.
See also: exocon
Source:
PAC, 2007, 79, 1153. (Glossary of terms used in toxicology, 2nd edition (IUPAC Recommendations 2007)) on page 1213 [Terms] [Paper]