Symptomatic Cutaneous Hepatic Porphyria and from Rats with Porphyria

1. Three tetracarboxylate porphyrins, apart from coproporphyrin, were isolated from the faeces of patients with symptomatic cutaneous hepatic porphyria and of rats with porphyria caused by hexachlorobenzene poisoning. The porphyrins were not present in the urine of the porphyric rats or in the faeces of control rats. 2. Two of the porphyrins were identified as tris-(2-carboxyethyl)-carboxymethyl ethyl trimethyl porphin (isocoproporphyrin) and tris-(2-carboxyethyl)-carboxymethyl trimethyl porphin (de-ethylisocoproporphyrin). 3. The third porphyrin, previously reported to be an analogue of coproporphyrin in which one propionate group is replaced by an aor ,B-hydroxypropionate group, was shown to be tris-(2-carboxyethyl)-carboxymethyl-(1-hydroxyethyl)trimethyl porphin (hydroxyisocoproporphyrin). 4. The order of fl-substituents around the porphin ring could not be determined for any of the compounds. 5. Evidence for the existence of a fourth porphyrin, tris-(2-carboxyethyl)-carboxymethyl trimethyl vinyl porphin (dehydroisocoproporphyrin), a postulated precursor of the others, is described. 6. It is suggested that dehydroisocoproporphyrinogen is produced by decarboxylationdehydrogenation ofone of the propionate groups of pentacarboxylate porphyrinogen III.