Heterocyclic Compounds [Chemical/Ingredient] Heterocyclic Compounds, 1-Ring [Chemical/Ingredient] Heterocyclic Cpds, 1-Ring C0019399 A class of organic compounds containing a ring structure made up of more than one kind of atom, usually carbon plus another atom. The ring structure can be aromatic or nonaromatic. Heterocyclic Compounds, 1-Ring D006573 5284 N0000008259 C26882 Heterocyclic Compounds, 1-Ring M0010292