- A porphyrin derivative characterized by the presence on each of the four pyrrole rings of one methyl group and one ethyl group; four isomeric forms are thus possible.
* * *etio·por·phy·rin or chiefly Brit ae·tio·por·phy·rin -'pȯr-fə-rən n any of four isomeric porphyrins C32H38N4 esp a violet crystalline pigment occurring in nature (as in petroleum and coal) and formed by degradation of chlorophyll and of heme
* * *etio·por·phyr·in (e″te-o-porґfə-rin) a porphyrin (q.v.) in which each pyrrole ring has one methyl and one ethyl side chain.
Medical dictionary. 2011.