4376 T3D4322 Uroporphyrin III Uroporphyrin is the porphyrin produced by oxidation of the methylene bridges in uroporphyrinogen. Uroporphyrins have four acetic acid and four propionic acid side chains attached to their pyrrole rings. The enzyme uroporphyrinogen I synthase catalyzes the formation of hydroxymethylbilane from four molecules of porphobilinogen. Uroporphyrinogen III cosynthase then catalyzes the conversion of hydroxymethylbilane into uroporphyrinogen III. Otherwise, hydroxymethylbilane cyclizes nonenzymatically to form uroporphyrinogen I. Uroporphyrinogen I and III yield their respective uroporphyrins via autooxidation or their respective coproporphyrinogens via decarboxylation. Excessive amounts of uroporphyrin I are excreted in congenital erythropoietic porphyria, and both uroporphyrin I and uroporphyrin III are excreted in porphyria cutanea tarda. Uroporphyrin I and III are the most common isomers. Under certain conditions, uroporphyrin III can act as a phototoxin, a neurotoxin, and a metabotoxin. A phototoxin leads to cell damage upon exposure to light. A neurotoxin causes damage to nerve cells and nerve tissues. A metabotoxin is an endogenously produced metabolite that causes adverse health effects at chronically high levels. Chronically high levels of porphyrins are associated with porphyrias such as porphyria variegate, acute intermittent porphyria, porphyria cutanea tarda, and hereditary coproporphyria (HCP). There are several types of porphyrias (most are inherited). Hepatic porphyrias are characterized by acute neurological attacks (seizures, psychosis, extreme back and abdominal pain, and an acute polyneuropathy), while the erythropoietic forms present with skin problems (usually a light-sensitive blistering rash and increased hair growth). The neurotoxicity of porphyrins may be due to their selective interactions with tubulin, which disrupt microtubule formation and cause neural malformations (PMID: 3441503). 18273-06-8 C40H38N4O16 White powder. No indication of carcinogenicity to humans (not listed by IARC). This is an endogenously produced metabolite found in the human body. It is used in metabolic reactions, catabolic reactions or waste generation. Chronically high levels of porophyrins are associated with porphyrias such as Porphyria variegate, Acute Intermittent Porphyria and Hereditary Coproporphyria (HCP). 2014-08-29T06:25:21Z 2018-03-21T17:46:22Z C02469 15436 UROPORPHYRIN_III DB04461 UFE true [H]\C-1=C2\N\C(=C([H])/C3=N/C(=C([H])\C4=C(CCC(O)=O)C(CC(O)=O)=C(N4)\C([H])=C4/N=C-1C(CCC(O)=O)=C4CC(O)=O)/C(CC(O)=O)=C3CCC(O)=O)C(CC(O)=O)=C2CCC(O)=O C40H38N4O16 InChI=1S/C40H38N4O16/c45-33(46)5-1-17-21(9-37(53)54)29-14-27-19(3-7-35(49)50)22(10-38(55)56)30(43-27)15-28-20(4-8-36(51)52)24(12-40(59)60)32(44-28)16-31-23(11-39(57)58)18(2-6-34(47)48)26(42-31)13-25(17)41-29/h13-16,41,44H,1-12H2,(H,45,46)(H,47,48)(H,49,50)(H,51,52)(H,53,54)(H,55,56)(H,57,58)(H,59,60)/b25-13-,26-13-,27-14-,28-15-,29-14-,30-15-,31-16-,32-16- InChIKey=VZVFNUAIRVUCEW-UJJXFSCMSA-N 830.7469 830.228281188 Endogenous Solid HMDB00916 16736727 <p>Ichiro Kojima, Kenji Maruhashi, Yasuo Fujiwara, &#8220;Process for producing coproporphyrin <span class="caps">III</span>.&#8221; U.S. Patent US4334021, issued September, 1978.</p>