84152-32-9Relevant articles and documents
Modeling Tryptophan/Indoleamine 2,3-Dioxygenase with Heme Superoxide Mimics: Is Ferryl the Key Intermediate?
Mondal, Pritam,Wijeratne, Gayan B.
, p. 1846 - 1856 (2020)
Tryptophan oxidation in biology has been recently implicated in a vast array of paramount pathogenic conditions in humans, including multiple sclerosis, rheumatoid arthritis, type-I diabetes, and cancer. This 2,3-dioxygenative cleavage of the indole ring of tryptophan with dioxygen is mediated by two heme enzymes, tryptophan 2,3-dioxygenase (TDO) and indoleamine 2,3-dioxygenase (IDO), during its conversion to N-formylkynurenine in the first and rate-limiting step of kynurenine pathway. Despite the pivotal significance of this enzymatic transformation, a vivid viewpoint of the precise mechanistic events is far from complete. A heme superoxide adduct is thought to be the active oxidant in both TDO and IDO, which, following O-O bond cleavage, presumably generates a key ferryl (FeIV=O) reaction intermediate. This study, for the first time in model chemistry, demonstrates the potential of synthetic heme superoxide adducts to mimic the bioinorganic chemistry of indole dioxygenation by TDO and IDO, challenging the widely accepted categorization of these metal adducts as weak oxidants. Herein, an electronically divergent series of ferric heme superoxo oxidants mediates the facile conversion of an array of indole substrates into their corresponding 2,3-dioxygenated products, while shedding light on an unequivocally occurring, putative ferryl intermediate. The oxygenated indole products have been isolated in a?31% yield, and characterized by LC-MS, 1H and 13C NMR, and FT-IR methodologies, as well as by 18O2(g) labeling experiments. Distinctly, the most electron-deficient superoxo adduct is observed to react the fastest, specifically with the most electron-rich indole substrate, underscoring the cruciality of electrophilicity of the heme superoxide moiety in facilitating the initial indole activation step. Comprehensive understanding of such mechanistic subtleties will benefit future attempts in the rational design of salient therapeutic agents, including next generation anticancer drug targets with amplified effectivity.
Photochemical reduction of nitrate and nitrite by manganese and iron porphyrins
Suslick, Kenneth S.,Watson, Randall A.
, p. 912 - 919 (2008/10/08)
New nitrate and nitrite complexes of metalloporphyrins have been synthesized and crystallographically characterized, and their photochemistry has been examined. Irradiation of Mn(TPP)(NO3) and Mn(TPP)(NO2) (where TPP = 5,10,15,20-tetraphenylporphyrinate(2-)) produces the high-valent metal-oxo species O=MnIV(TPP) quantitatively, with quantum yields of 1.58 × 10-4 and 5.30 × 10-4, respectively. This metal-oxo species is capable of oxidizing substrates, as demonstrated in reactions with styrene or triphenylphosphine. Mn(TPP)(NO2) is formed as an intermediate in the complete photolysis of Mn(TPP)(NO3). Similarly, the photochemistry of Fe(TPP)(NO3) produces substrate oxidation, including C-H hydroxylation, which suggests the photochemical formation of O=FeIV(TPP.+) as the active oxidant. Remarkably, all three oxygen atoms of the initially bound NO3- can be used for substrate oxidation. The X-ray crystal structures of Mn(TPP)(NO3)·2C6H6 and Mn(TPP)(NO2)·C6H6 have been solved. In the nitrate complex Mn(TPP)(NO3), the average Mn-pyrrole N distance is 2.007 A?, with the metal 0.21 A? above the mean plane of the nitrogen atoms. The nitrate ion is coordinated in a unidentate fashion with a Mn-O bond length of 2.101 A?. Mn(TPP)(NO2) is the first metalloporphyrin complex with oxygen-bound nitrite. The average Mn-pyrrole nitrogen distance is 2.012 A?, with the metal 0.23 A? above the mean plane of the nitrogen atoms. The nitrite ion is coordinated through one of the oxygens, with a Mn-O bond length of 2.059 A?. Crystal data for Mn(TPP)(NO3)·2C6H6 at -76°C: space group P1, a = 13.271 (4) A?, b = 13.610 (5) A?, c = 12.880 (3) A?, α = 111.44 (2)°, β = 95.71 (2)°, γ = 85.50 (3)°, V = 2152 (2) A?3, Z = 2, RF = 0.063, RwF = 0.086 for 408 variables and 4890 unique data with I > 2.58σ(I). Crystal data for Mn(TPP)(NO2)·C6H6: space group Pccn, a = 21.631 (11) A?, b = 19.941 (12) A?, c = 17.991 (6) A?, V = 7760 (7) A?3, Z = 8, RF = 0.062, RwF = 0.096 for 543 variables and 3820 unique data with I > 2.58σ(I).
MECHANISTIC CONSIDERATIONS IN THE PHOTODIPPROPORTIONATION OF μ-OXO-BIS ((TETRAPHENYLPORPHINATO)IRON(III))
Peterson, Mark W.,Rivers, David S.,Richman, Robert M.
, p. 2907 - 2915 (2007/10/02)
The photochemistry of μ-oxo-bis((tetraphenylporphinato)iron(III)) has been studied.Both continuous and photolysis establish a photochemical disproportionation to fom the ferrous complex FeTPP and the ferryl complex FeOTTP: Using triphenylphosp
