Porphyrin

PORPHYRIN. Porphyrins—products of transformation of Hb, not containing iron. The basic system, from which all P. are derived—porphin, a compound of 4 pyrrole nuclei (see) connected by 4 methine groups CH. Etioporphyrin from the coloring matter of blood, C₃₂H₃₈N₄ (Willstätter)—porphin, in the pyrrole rings of which 4H are replaced by methyl and 4H by ethyl groups (4 isomers).-1. Natural P. 1. Primary P., found in nature in ready form. Uroporphyrin, C₄₀H₃₈N₄O₁₆; characterized by eight carboxyl groups in the etioporphyrin molecule. In normal urine is found in small amounts; increases with poisoning by sulfonal, trional, when working with lead, as well as under the action of chloroform, zinc chloride, thiozaminum, novocaine, in typhus, in genuine porphyria (Gunther). Uroporphyrin and coproporphyrin (see below) by many authors were erroneously taken for hematoporphyrin. Uroporphyrin is found in organs in porphyria, mainly in bones and bone marrow. Coproporphyrin, C₃₆H₃₈N₄O₈, contains four carboxyl groups; is obtained by the removal of four carboxyl groups from uroporphyrin. Found in feces and urine under the same conditions as uroporphyrin. Found in yeast. Turacin, C₄₀H₃₆N₄O₁₆Cu, copper salt of uroporphyrin, found in the feathers of some birds (Church). Ooporphyrin C₃₄H₃₄N₄O₄, identical with protoporphyrin and porphyrin of Kammerer (see below); isolated from spotted eggshell. Conchioporphyrin, C₃₇H₃₈N₄O₁₀,—monocarboxylated coproporphyrin; found in the nacre of Pteria radiata. 2. Secondary P., obtained artificially by biological means. Porphyrin of Kammerer, C₃₄H₃₄N₄O₄; obtained by the action of bacteria on blood (Kammerer), during putrefaction and autolysis of meat (Fischer, Schneegass); is also obtained from hemin by the action of iodo- or bromo-hydrogenic acid, by the action of formic acid and iron on hemin (Fischer); when blood is poured into concentrated HCl. Deuteroporphyrin, C₃₀H₃₀N₄O₄, is obtained during prolonged putrefaction of meat.

II. Synthetic P. from blood pigment. Mesoporphyrin, C₃₄H₃₈N₄O₄, corresponds to reduced hemin—mesohemin—C₃₄H₃₄N₄O₄FeCl (Fischer, Willstätter); differs from etioporphyrin in that in two ethyl groups one hydrogen atom is replaced by carboxyl. Obtained by careful reduction of hemin with hydriodic acid and phosphonium iodide (Nentsky and Zalesky) or by the action of alcoholate on hemin (Fischer, Rose et al.).-Hematoporphyrin, C₃₄H₃₈N₄O₆, differs from mesoporphyrin by the replacement of hydrogen in two ethyl groups by hydroxyls. Obtained by the action on hemin of hydrobromic and acetic acids.-Porphyrinogen, C₃₄H₄₄N₄O₄, a colorless derivative of P. Obtained by reduction of mesoporphyrin. Relates to mesoporphyrin as leuco-base to dye. It is unable to complexly bind iron. Most P. possess basic properties due to pyrrole rings, form complex salts with metals; also has acid properties due to carboxyl groups—formation of esters. Give characteristic spectra. In addition to the P. mentioned above, were found in organs of embryonic and adult animals in small amounts; in porphyria the quantity and distribution of P. increases. Accumulations of P. are found in the Harderian gland of rodents. In embryos erythroblasts contain P. (Borst); in pernicious anemia in erythro- and megablasts large amounts of P. are found, which indicates the transition of blood-forming tissue to embryonic type. Borst considers bone marrow and liver the place of synthesis of P. Some of the P. have a sensitizing effect on the organism with respect to light energy (see Hemoglobin, products of hemoglobin breakdown). From chlorophyll, by the action of alkalis, pyroporphyrin, rhodoporphyrin and phylloporphyrin were obtained; in the first two the main nucleus of porphyrin is the same as in the porphyrins of the blood coloring matter; in the nucleus of phylloporphyrin one of the methine groups (see above) is replaced by another group (according to Fischer, group I or || . Fischer and Riedl succeeded in converting pyroporphyrin (chlorophyll P.) into mesoporphyrin (P. of blood pigment). Magnesium is part of chlorophyll.-Methods for determination of P. in urine (see also Urine). 1. Precipitation with 10% caustic soda. The precipitate of phosphates with P. is filtered, washed, dried, and examined spectroscopically. The spectrum of uroporphyrin in acid solution: 3 bands—598-590 mμ; 576-571 mμ; 558.5-544 mμ; of coproporphyrin: 596-588 mμ; 555-541 mμ and a shadow at 670 mμ (Schumm). 2. The washed precipitate of phosphates (see above) is triturated with an alcoholic solution of hydrochloric acid (8 parts alcohol and 2 parts HCl) and heated on a water bath. Fluorescence is observed.