Phenyl biliverdin isomers obtained by chemical oxidation of iron(III) complex of 5-phenyl protoporphyrin IX

Abstract

Oxidative cleavage of synthetic 5-phenyl protohemin IX in pyridine solution in the presence of ascorbic acid (coupled oxidation), followed by esterification of the products with boron trifluoride-methanol rendered mainly three isomeric biliverdins. These were identified by MS and 1D and 2D 1 H NMR as 15-phenyl biliverdin IXβ (1), 10-phenyl biliverdin IXγ (2) and 5-phenyl biliverdin IXδ (3) dimethyl esters. The fact that biliverdin IXα dimethyl ester derivative is not obtained indicates that oxidation fails to occur in the α-meso-carbon bearing the phenyl group.

Isoporphyrin Intermediate in Heme Oxygenase Catalysis

“…The dimethyl esterified biliverdin isomers were prepared from the corresponding heme by coupled oxidation in the presence of pyridine, O 2 , and ascorbic acid according to published procedures (27,28 (29). Enzymes-Truncated hHO-1 lacking the 23 C-terminal residues was expressed and purified according to published procedures (23,30,31).…”

Synthesis of Biladienone and Bilatrienone by Coupled Oxidation of Tetraarylporphyrins

“…Although meso-substituted porphyrins were employed as a substrate for the enzyme reactions, the substrate of the coupled oxidation has been limited to the iron complexes of meso-unsubstituted porphyrins such as protoporphyrin IX and octaethylporphyrin. Recently, Niemevz et al reported that meso -monophenylporphyrin underwent coupled oxidation where the meso-unsubstituted carbon was selectively oxidized …”