has role histamine ammonium ion derivative histaminium histaminium cation NTYJJOPFIAHURM-UHFFFAOYSA-O histamine 112.08692 2-(1H-imidazol-4-yl)ethanaminium C5H10N3 +1 112.15300 CHEBI:58432 chebi_ontology An ammonium ion that is the conjugate acid of histamine protonated on the side-chain nitrogen. [NH3+]CCc1c[nH]cn1 InChI=1S/C5H9N3/c6-2-1-5-3-7-4-8-5/h3-4H,1-2,6H2,(H,7,8)/p+1 mouse metabolite human metabolite