scholarly journals COMPARISON OF DEGRADATION CAPACITY OF OXIDATION AND PHOTOOXIDATION OF SULFIDE CATALYZED BY Zn(II) TETRASULFOPHTHALOCYANINE VÀ Co(II) TETRASULFOPHTHALOCYANINE

2009 ◽  
Vol 12 (7) ◽  
pp. 43-47
Author(s):  
Minh Thanh Le ◽  
Thao Thanh Phan ◽  
Tung Cao Thanh Pham ◽  
Tan Minh Phan
Keyword(s):  
Electron Transfer ◽  
Singlet Oxygen ◽  
Transfer Mechanism ◽  
Type I ◽  
Type Ii ◽  
Electron Transfer Mechanism ◽  
Catalytic Activities ◽  
Visible Irradiation

The oxidation and photooxidation of sulfide catalyzed by soluble phthalocynines were carried out. The results showed that both Zinc(II) Tetrasulfophthalocyanine (ZnTSPc) and Cobalt(II) Tetrasulfophthalocyanine (COTSPC) have catalytic activities in the oxidation of Sulfide. The degradation yiel minute under the light visible irradiation and in the dark were 96,61% and 71,11% respectively. Whereas, in case of CoTSPc during 40 minute, these were 98,10% and 96,30%, respectively. ZnTSPc demonstrates the photoactive property and catalyses the reaction via type II (singlet oxygen mechanism). COTSPc has not the photoactive property and catalyses the reaction via type I (electron transfer mechanism).

Ground- and excited-state interactions of 2,7,12,17-tetraphenylporphycene with model target biomolecules for type-I photodynamic therapy

2009 ◽  
Vol 13 (01) ◽  
pp. 99-106 ◽  
Author(s):  
Noemí Rubio ◽  
Víctor Martínez-Junza ◽  
Jordi Estruga ◽  
José I. Borrell ◽  
Margarita Mora ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Photodynamic Therapy ◽  
Excited State ◽  
Singlet Oxygen ◽  
Cell Lines ◽  
Mechanism Of Action ◽  
Photophysical Properties ◽  
Type I ◽  
Type Ii ◽  
Hydrophobic Compound

Biosubstrate-sensitizer binding is one of the factors that enhances the type-I mechanism over the type-II in the whole photodynamic process. 2,7,12,17-Tetraphenylporphycene (TPPo), a second-generation photosensitizer, is a hydrophobic compound with good photophysical properties for photodynamic therapy applications that has proved its ability for the photoinactivation of different cell lines. Nevertheless, little is known about its mechanism of action. This paper focuses on the study of the interaction/binding of TPPo with different model biomolecules that may favor the type-I mechanism in the overall photodynamic process, including nucleosides, proteins, and phospholipids. Compared with more hydrophilic photosensitizers, it is concluded that TPPo is more likely to undergo type-II (singlet oxygen) than type-I (electron transfer) photodynamic processes in biological environments.

Photosensitized damage of protein by fluorinated diethoxyphosphorus(V)porphyrin

2013 ◽  
Vol 17 (01n02) ◽  
pp. 56-62 ◽  
Author(s):  
Kazutaka Hirakawa ◽  
Keito Azumi ◽  
Yoshinobu Nishimura ◽  
Tatsuo Arai ◽  
Yoshio Nosaka ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Human Serum Albumin ◽  
Serum Albumin ◽  
Singlet Oxygen ◽  
Human Serum ◽  
Transfer Mechanism ◽  
Water Soluble ◽  
Electron Transfer Mechanism ◽  
Oxygen Generation ◽  
Singlet Oxygen Generation

The effect of the axial ligand fluorination of the water-soluble P(V)porphyrin complex on photosensitized protein damage was examined. The activity of singlet oxygen generation by diethoxyP(V) porphyrin was slightly improved by the fluorination of the ethoxy chains. Absorption spectrum measurements demonstrated the binding interaction between the P(V)porphyrins and human serum albumin, a water-soluble protein. Photo-irradiated P(V)porphyrins damaged the amino acid residue of human serum albumin, resulting in the decrease of the fluorescence intensity from the tryptophan residue of human serum albumin. A singlet oxygen quencher, sodium azide, could not completely inhibit the damage of human serum albumin, suggesting that the electron transfer mechanism contributes to protein damage as does singlet oxygen generation. The decrease of the fluorescence lifetime of P(V)porphyrin by human serum albumin supported the electron transfer mechanism. The estimated contributions of the electron transfer mechanism are 0.57 and 0.44 for the fluorinated and non-fluorinated P(V)porphyrins, respectively. The total quantum yield of the protein photo-oxidation was slightly enhanced by this axial fluorination.

scholarly journals Inorganic Salts and Antimicrobial Photodynamic Therapy: Mechanistic Conundrums?

Molecules ◽  
2018 ◽  
Vol 23 (12) ◽  
pp. 3190 ◽  
Author(s):  
Michael R. Hamblin ◽  
Heidi Abrahamse
Keyword(s):  
Electron Transfer ◽  
Titanium Dioxide ◽  
Singlet Oxygen ◽  
Potassium Thiocyanate ◽  
Molecular Iodine ◽  
Water Soluble ◽  
Inorganic Salts ◽  
Type I ◽  
Bacterial Cells ◽  
Type Ii

We have recently discovered that the photodynamic action of many different photosensitizers (PSs) can be dramatically potentiated by addition of a solution containing a range of different inorganic salts. Most of these studies have centered around antimicrobial photodynamic inactivation that kills Gram-negative and Gram-positive bacteria in suspension. Addition of non-toxic water-soluble salts during illumination can kill up to six additional logs of bacterial cells (one million-fold improvement). The PSs investigated range from those that undergo mainly Type I photochemical mechanisms (electron transfer to produce superoxide, hydrogen peroxide, and hydroxyl radicals), such as phenothiazinium dyes, fullerenes, and titanium dioxide, to those that are mainly Type II (energy transfer to produce singlet oxygen), such as porphyrins, and Rose Bengal. At one extreme of the salts is sodium azide, that quenches singlet oxygen but can produce azide radicals (presumed to be highly reactive) via electron transfer from photoexcited phenothiazinium dyes. Potassium iodide is oxidized to molecular iodine by both Type I and Type II PSs, but may also form reactive iodine species. Potassium bromide is oxidized to hypobromite, but only by titanium dioxide photocatalysis (Type I). Potassium thiocyanate appears to require a mixture of Type I and Type II photochemistry to first produce sulfite, that can then form the sulfur trioxide radical anion. Potassium selenocyanate can react with either Type I or Type II (or indeed with other oxidizing agents) to produce the semi-stable selenocyanogen (SCN)2. Finally, sodium nitrite may react with either Type I or Type II PSs to produce peroxynitrate (again, semi-stable) that can kill bacteria and nitrate tyrosine. Many of these salts (except azide) are non-toxic, and may be clinically applicable.

[60]Fullerene Supported on Silica and γ-Alumina Sensitized Photooxidation of Olefins: Chemical Evidence for Singlet Oxygen and Electron Transfer Mechanism

Synlett ◽  
2004 ◽  
pp. 971-974
Author(s):  
Michael Orfanopoulos ◽  
Georgios C. Vougioukalakis ◽  
Yiannis Angelis ◽  
John Vakros ◽  
George Panagiotou ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Singlet Oxygen ◽  
Transfer Mechanism ◽  
Electron Transfer Mechanism ◽  
Chemical Evidence

Tetrakis(N-methyl-p-pyridinio)porphyrin and its zinc complex can photosensitize damage of human serum albumin through electron transfer and singlet oxygen generation

2016 ◽  
Vol 20 (07) ◽  
pp. 813-821 ◽  
Author(s):  
Dongyan Ouyang ◽  
Shiori Inoue ◽  
Shigetoshi Okazaki ◽  
Kazutaka Hirakawa
Keyword(s):  
Electron Transfer ◽  
Human Serum Albumin ◽  
Serum Albumin ◽  
Singlet Oxygen ◽  
Human Serum ◽  
Sodium Azide ◽  
Zinc Complex ◽  
Transfer Mechanism ◽  
Protein Damage ◽  
Electron Transfer Mechanism

The photosensitized protein-damaging activity of water-soluble freebase tetrakis([Formula: see text]-methyl-[Formula: see text]-pyridinio)porphyrin (H2TMPyP), and its zinc complex (ZnTMPyP) was investigated using human serum albumin (HSA) as a target protein. These porphyrins bound to HSA and caused photosensitized oxidation of the tryptophan residue. The protein damage was enhanced in deuterium oxide and inhibited by sodium azide, a physical quencher of singlet oxygen, suggesting the contribution of singlet oxygen. However, an excess amount of sodium azide could not completely inhibit protein damage. These findings suggest the partial contribution of another mechanism to the protein damage, possibly the electron transfer mechanism. The Gibbs free energy of the electron transfer mechanism showed that electron transfer-mediated tryptophan oxidation by photoexcited H2TMPyP is more advantageous than that by ZnTMPyP. Actually, the quantum yield of protein damage through electron transfer by H2TMPyP was larger than that by ZnTMPyP. In addition, this study demonstrated that the association between porphyrin and protein plays an important role in photosensitized protein damage.

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