Isoalloxazine

Part of speech: noun

Definitions

1. A heterocyclic organic compound with a three-ring structure that forms the core of flavin molecules such as riboflavin
2. Any member of a family of nitrogen-containing ring compounds that serves as the basic chemical framework of riboflavin and related pigments
3. A tricyclic chemical structure, built from fused rings containing nitrogen, that underlies riboflavin and other flavin coenzymes

Etymology: Isoalloxazine is a chemical coinage built from two parts. The first, "iso-", comes from the Ancient Greek "isos", meaning "equal" or "same," and in chemistry it marks an isomer: a compound with the same atoms arranged differently. The second part is "alloxazine," the name of a related ring system, so the word names a rearranged variant of that structure. The structure matters more than the name. Isoalloxazine is a tricyclic system of three fused rings, two of them containing nitrogen atoms, and it forms the core of riboflavin (vitamin B2) and the flavin coenzymes that cells use to carry electrons in metabolism. The ring system itself is what the chemistry depends on, and the name records the family relationship to alloxazine.