scholarly journals Manganese Porphyrin-Based SOD Mimetics Produce Polysulfides from Hydrogen Sulfide

Antioxidants ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 639 ◽  
Author(s):  
Kenneth R. Olson ◽  
Yan Gao ◽  
Faihaan Arif ◽  
Shivali Patel ◽  
Xiaotong Yuan ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Hydrogen Sulfide ◽  
Sulfide Oxidation ◽  
Manganese Porphyrin ◽  
Phase Ii Clinical Trials ◽  
Protein Thiols ◽  
Oxidation Of Hydrogen ◽  
Hydrogen Persulfide ◽  
Mediated Reduction ◽  
Absorbance Spectra

Manganese-centered porphyrins (MnPs), MnTE-2-PyP5+ (MnTE), MnTnHex-2-PyP5+ (MnTnHex), and MnTnBuOE-2-PyP5+ (MnTnBuOE) have received considerable attention because of their ability to serve as superoxide dismutase (SOD) mimetics thereby producing hydrogen peroxide (H2O2), and oxidants of ascorbate and simple aminothiols or protein thiols. MnTE-2-PyP5+ and MnTnBuOE-2-PyP5+ are now in five Phase II clinical trials warranting further exploration of their rich redox-based biology. Previously, we reported that SOD is also a sulfide oxidase catalyzing the oxidation of hydrogen sulfide (H2S) to hydrogen persulfide (H2S2) and longer-chain polysulfides (H2Sn, n = 3–7). We hypothesized that MnPs may have similar actions on sulfide metabolism. H2S and polysulfides were monitored in fluorimetric assays with 7-azido-4-methylcoumarin (AzMC) and 3′,6′-di(O-thiosalicyl)fluorescein (SSP4), respectively, and specific polysulfides were further identified by mass spectrometry. MnPs concentration-dependently consumed H2S and produced H2S2 and subsequently longer-chain polysulfides. This reaction appeared to be O2-dependent. MnP absorbance spectra exhibited wavelength shifts in the Soret and Q bands characteristic of sulfide-mediated reduction of Mn. Taken together, our results suggest that MnPs can become efficacious activators of a variety of cytoprotective processes by acting as sulfide oxidation catalysts generating per/polysulfides.

Reduced Mechanism for the Oxidation of Hydrogen Sulfide

2009 ◽  
Author(s):  
H. Selim ◽  
A. K. Gupta ◽  
M. Sassi
Keyword(s):  
Hydrogen Sulfide ◽  
Oil And Gas ◽  
Sulfide Oxidation ◽  
Harmful Effect ◽  
Reaction Conditions ◽  
Efficient Manner ◽  
Detailed Chemistry ◽  
Reduced Mechanism ◽  
Oxidation Of Hydrogen ◽  
The Difference

Hydrogen sulfide is one of the most common gases accompanying fuels in oil and gas refinery processes. This gas has very harmful effect on the human health and environment so that it must be removed in an effective and efficient manner before using this fuel. These problems triggered the interest to study the chemistry of hydrogen sulfide oxidation, as it is mainly treated by chemical reactions. Simplification of the reaction mechanism will enable us to understand the properties of the chemical processes that occur during the process of hydrogen sulfide treatment. Reduction strategy is carried out here in order to reduce the detailed mechanism, where the direct relation graph and error propagation methodology (DRGEP) has been used in this paper. The results obtained from the resulting reduced mechanism showed very good agreement with the detailed chemistry results under different reaction conditions. However, some discrepancies have been found for some species, especially in the hydrogen and oxygen mole fractions. The reduced mechanism is also capable of tracking the difference in chemical kinetics that takes place due to the change in reaction conditions.

Oxidation of hydrogen sulfide over Fe2O3/Al2O3 catalyst: Influence of support texture and Fe2O3 precursor

1991 ◽  
Vol 56 (9) ◽  
pp. 1893-1899 ◽  
Author(s):  
Michal Novák ◽  
Miroslav Zdražil
Keyword(s):  
Catalytic Activity ◽  
Hydrogen Sulfide ◽  
Porous Structure ◽  
Sulfide Oxidation ◽  
Reaction Products ◽  
Hydrogen Sulfide Oxidation ◽  
Two Factors ◽  
Oxidation Of Hydrogen ◽  
Comparable Activity ◽  
Value Of It

Activity and selectivity in hydrogen sulfide oxidation by oxygen on a Fe2O3/α-Al2O3 catalyst was studied at 200°C and atmospheric pressure. Reaction products were sulfur and sulfur dioxide. Two factors influencing catalytic activity were studied: support porous structure and the type of Fe2O3 precursor. The porous structure influenced substantially catalytic activity; mesopores were more active than macropores. The catalysts prepared from Fe(NO3)3 and iron(III) acetylacetonate exhibited comparable activity, the lower activity was found for the catalyst prepared from Fe2(SO4)3. The selectivity to sulfur formation was higher on catalysts containing greater amount of macropores and the value of it changed in the interval 0-85% depending on the type of catalyst.

scholarly journals Oxidation of Hydrogen Sulfide by Quinones: How Polyphenols Initiate Their Cytoprotective Effects

2021 ◽  
Vol 22 (2) ◽  
pp. 961
Author(s):  
Kenneth R. Olson ◽  
Yan Gao ◽  
Karl D. Straub
Keyword(s):  
Shikimic Acid ◽  
Sulfur Metabolism ◽  
Hek293 Cells ◽  
Direct Reaction ◽  
Semiquinone Radical ◽  
Radical Intermediate ◽  
Oxidation Of Hydrogen ◽  
Health Promoting ◽  
Mediated Reduction ◽  
Absorbance Spectra

We have shown that autoxidized polyphenolic nutraceuticals oxidize H2S to polysulfides and thiosulfate and this may convey their cytoprotective effects. Polyphenol reactivity is largely attributed to the B ring, which is usually a form of hydroxyquinone (HQ). Here, we examine the effects of HQs on sulfur metabolism using H2S- and polysulfide-specific fluorophores (AzMC and SSP4, respectively) and thiosulfate sensitive silver nanoparticles (AgNP). In buffer, 1,4-dihydroxybenzene (1,4-DB), 1,4-benzoquinone (1,4-BQ), pyrogallol (PG) and gallic acid (GA) oxidized H2S to polysulfides and thiosulfate, whereas 1,2-DB, 1,3-DB, 1,2-dihydroxy,3,4-benzoquinone and shikimic acid did not. In addition, 1,4-DB, 1,4-BQ, PG and GA also increased polysulfide production in HEK293 cells. In buffer, H2S oxidation by 1,4-DB was oxygen-dependent, partially inhibited by tempol and trolox, and absorbance spectra were consistent with redox cycling between HQ autoxidation and H2S-mediated reduction. Neither 1,2-DB, 1,3-DB, 1,4-DB nor 1,4-BQ reduced polysulfides to H2S in either 21% or 0% oxygen. Epinephrine and norepinephrine also oxidized H2S to polysulfides and thiosulfate; dopamine and tyrosine were ineffective. Polyphenones were also examined, but only 2,5-dihydroxy- and 2,3,4-trihydroxybenzophenones oxidized H2S. These results show that H2S is readily oxidized by specific hydroxyquinones and quinones, most likely through the formation of a semiquinone radical intermediate derived from either reaction of oxygen with the reduced quinones, or from direct reaction between H2S and quinones. We propose that polysulfide production by these reactions contributes to the health-promoting benefits of polyphenolic nutraceuticals.

Simulation of sulfide buildup in wastewater and atmosphere of sewer networks

2005 ◽  
Vol 52 (3) ◽  
pp. 201-208 ◽  
Author(s):  
A.H. Nielsen ◽  
C. Yongsiri ◽  
T. Hvitved-Jacobsen ◽  
J. Vollertsen
Keyword(s):  
Hydrogen Sulfide ◽  
Sulfide Oxidation ◽  
Sulfur Cycle ◽  
Model Concept ◽  
Concrete Corrosion ◽  
Sulfide Production ◽  
Oxidation Of Hydrogen ◽  
Sulfide Precipitation ◽  
Further Development ◽  
Sewer Networks

A model concept for prediction of sulfide buildup in sewer networks is presented. The model concept is an extension to – and a further development of – the WATS model (Wastewater Aerobic-anaerobic Transformations in Sewers), which has been developed by Hvitved-Jacobsen and co-workers at Aalborg University. In addition to the sulfur cycle, the WATS model simulates changes in dissolved oxygen and carbon fractions of different biodegradability. The sulfur cycle was introduced via six processes: 1. sulfide production taking place in the biofilm covering the permanently wetted sewer walls; 2. biological sulfide oxidation in the permanently wetted biofilm; 3. chemical and biological sulfide oxidation in the water phase; 4. sulfide precipitation with metals present in the wastewater; 5. emission of hydrogen sulfide to the sewer atmosphere and 6. adsorption and oxidation of hydrogen sulfide on the moist sewer walls where concrete corrosion may take place.

Novel aqueous chelating agents for catalytic oxidation of hydrogen sulfide to sulfur by air

2005 ◽  
Vol 4 (2) ◽  
pp. 157-175 ◽  
Author(s):  
Guoxiong Hua ◽  
Qingzhi Zhang ◽  
Derek McManus ◽  
Alex M. Z. Slawin ◽  
J. Derek Woollins
Keyword(s):  
Hydrogen Sulfide ◽  
Catalytic Oxidation ◽  
Chelating Agents ◽  
Oxidation Of Hydrogen
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