Oxidative Stress in Vitiligo: Photo-oxidation of Pterins Produces H2O2 and Pterin-6-carboxylic Acid

2002 ◽  
Vol 292 (4) ◽  
pp. 805-811 ◽  
Author(s):  
Hartmut Rokos ◽  
Wayne D. Beazley ◽  
Karin U. Schallreuter
Keyword(s):  
Oxidative Stress ◽  
Carboxylic Acid ◽  
Photo Oxidation

ChemInform Abstract: Facile and Efficient Synthesis of Hydroxyalkyl Esters from Cyclic Acetals Through Aerobic Photo-Oxidation Using Anthraquinone-2-carboxylic Acid.

ChemInform ◽  
2015 ◽  
Vol 46 (30) ◽  
pp. no-no
Author(s):  
Tomoaki Yamaguchi ◽  
Yasuhisa Kudo ◽  
Shin-ichi Hirashima ◽  
Eiji Yamaguchi ◽  
Norihiro Tada ◽  
...  
Keyword(s):  
Carboxylic Acid ◽  
Efficient Synthesis ◽  
Cyclic Acetals ◽  
Photo Oxidation

scholarly journals Mass Spectrometric Analysis of l-Cysteine Metabolism: Physiological Role and Fate of l-Cysteine in the Enteric Protozoan Parasite Entamoeba histolytica

mBio ◽  
2014 ◽  
Vol 5 (6) ◽  
Author(s):  
Ghulam Jeelani ◽  
Dan Sato ◽  
Tomoyoshi Soga ◽  
Haruo Watanabe ◽  
Tomoyoshi Nozaki
Keyword(s):  
Oxidative Stress ◽  
Amino Acid ◽  
Carboxylic Acid ◽  
Stable Isotope ◽  
Carboxylic Acids ◽  
Entamoeba Histolytica ◽  
Protozoan Parasite ◽  
Protozoan Parasites ◽  
Metabolic Fate ◽  
Content Type

ABSTRACTl-Cysteine is essential for virtually all living organisms, from bacteria to higher eukaryotes. Besides having a role in the synthesis of virtually all proteins and of taurine, cysteamine, glutathione, and other redox-regulating proteins,l-cysteine has important functions under anaerobic/microaerophilic conditions. In anaerobic or microaerophilic protozoan parasites, such asEntamoeba histolytica,l-cysteine has been implicated in growth, attachment, survival, and protection from oxidative stress. However, a specific role of this amino acid or related metabolic intermediates is not well understood. In this study, using stable-isotope-labeledl-cysteine and capillary electrophoresis-time of flight mass spectrometry, we investigated the metabolism ofl-cysteine inE. histolytica. [U-13C3,15N]l-cysteine was rapidly metabolized into three unknown metabolites, besidesl-cystine andl-alanine. These metabolites were identified as thiazolidine-4-carboxylic acid (T4C), 2-methyl thiazolidine-4-carboxylic acid (MT4C), and 2-ethyl-thiazolidine-4-carboxylic acid (ET4C), the condensation products ofl-cysteine with aldehydes. We demonstrated that these 2-(R)-thiazolidine-4-carboxylic acids serve for storage ofl-cysteine. Liberation ofl-cysteine occurred when T4C was incubated with amebic lysates, suggesting enzymatic degradation of thesel-cysteine derivatives. Furthermore, T4C and MT4C significantly enhanced trophozoite growth and reduced intracellular reactive oxygen species (ROS) levels when it was added to cultures, suggesting that 2-(R)-thiazolidine-4-carboxylic acids are involved in the defense against oxidative stress.IMPORTANCEAmebiasis is a human parasitic disease caused by the protozoan parasiteEntamoeba histolytica. In this parasite,l-cysteine is the principal low-molecular-weight thiol and is assumed to play a significant role in supplying the amino acid during trophozoite invasion, particularly when the parasites move from the anaerobic intestinal lumen to highly oxygenated tissues in the intestine and the liver. It is well known thatE. histolyticaneeds a comparatively high concentration ofl-cysteine for its axenic cultivation. However, the reason for and the metabolic fate ofl-cysteine in this parasite are not well understood. Here, using a metabolomic and stable-isotope-labeled approach, we investigated the metabolic fate of this amino acid in these parasites. We found thatl-cysteine inside the cell rapidly reacts with aldehydes to form 2-(R)-thiazolidine-4-carboxylic acid. We showed that these 2-(R)-thiazolidine-4-carboxylic derivatives serve as anl-cysteine source, promote growth, and protect cells against oxidative stress by scavenging aldehydes and reducing the ROS level. Our findings represent the first demonstration of 2-(R)-thiazolidine-4-carboxylic acids and their roles in protozoan parasites.

scholarly journals Mechanisms of Action of Escapin, a Bactericidal Agent in the Ink Secretion of the Sea Hare Aplysia californica: Rapid and Long-Lasting DNA Condensation and Involvement of the OxyR-Regulated Oxidative Stress Pathway

2012 ◽  
Vol 56 (4) ◽  
pp. 1725-1734 ◽  
Author(s):  
Ko-Chun Ko ◽  
Phang C. Tai ◽  
Charles D. Derby
Keyword(s):  
Oxidative Stress ◽  
Carboxylic Acid ◽  
Dna Binding ◽  
Binding Protein ◽  
Aplysia Californica ◽  
Dna Binding Protein ◽  
Bactericidal Effect ◽  
Dna Condensation ◽  
Maximal Effect ◽  
Content Type

ABSTRACTThe marine snailAplysia californicaproduces escapin, anl-amino acid oxidase, in its defensive ink. Escapin usesl-lysine to produce diverse products called escapin intermediate products ofl-lysine (EIP-K), including α-amino-ε-caproic acid, Δ1-piperidine-2-carboxylic acid, and Δ2-piperidine-2-carboxylic acid. EIP-K and H2O2together, but neither alone, is a powerful bactericide. Here, we report bactericidal mechanisms of escapin products onEscherichia coli. We show that EIP-K and H2O2together cause rapid and long-lasting DNA condensation: 2-min treatment causes significant DNA condensation and killing, and 10-min treatment causes maximal effect, lasting at least 70 h. We isolated two mutants resistant to EIP-K plus H2O2, both having a single missense mutation in the oxidation regulatory gene,oxyR. A complementation assay showed that the mutated gene,oxyR(A233V), renders resistance to EIP-K plus H2O2, and a gene dosage effect leads to reduction of resistance for strains carrying wild-typeoxyR. Temperature stress with EIP-K does not produce the bactericidal effect, suggesting the effect is due to a specific response to oxidative stress. The null mutant for any single DNA-binding protein—Dps, H-NS, Hup, Him, or MukB—was not resistant to EIP-K plus H2O2, suggesting that no single DNA-binding protein is necessary to mediate this bactericidal effect, but allowing for the possibility that EIP-K plus H2O2could function through a combination of DNA-binding proteins. The bactericidal effect of EIP-K plus H2O2was eliminated by the ferrous ion chelator 1,10-phenanthroline, and it was reduced by the hydroxyl radical scavenger thiourea, suggesting hydroxyl radicals mediate the effects of EIP-K plus H2O2.

scholarly journals The synthesis and the antioxidant activity of 1-phenoxymethyl-4-aryl-5,6,7,8-tetrahydro-2a,4a,8a-triazacyclopenta[cd]azulene-3-carboxylic (or carbothionic) acid derivatives

Pharmacia ◽  
2021 ◽  
Vol 68 (1) ◽  
pp. 251-258
Author(s):  
Sergii Demchenko ◽  
Hanna Yeromina ◽  
Yulia Fedchenkova ◽  
Zinaida Ieromina ◽  
Vitaliy Yaremenko ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Antioxidant Activity ◽  
Ascorbic Acid ◽  
Carboxylic Acid ◽  
In Silico ◽  
Pharmacokinetic Profile ◽  
High Antioxidant Activity ◽  
Pharmacological Screening

New 1-phenoxymethyl-4-aryl-5,6,7,8-tetrahydro-2а,4a,8a-triazacyclopenta[cd]azulene-3-carboxylic (or carbothionic) acid derivatives have been designed, synthesized and evaluated for their in vitro antioxidant activity under conditions of the artificial oxidative stress using ionol, ascorbic acid and α-tocopherol as the reference drugs. It has been found that 1-phenoxymethyl-4-aryl-5,6,7,8-tetrahydro-2а,4a,8a-triazacyclopenta[cd]azulene-3-carbothionic acid derivatives 9b, 9c, 9d, 9e, 9f, 9i and 1-phenoxymethyl-4-(41-chlorophenyl)-5,6,7,8-tetrahydro-2,2a,8-triazacyclopenta[cd]azulene-3-carboxylic acid phenylamide 10 reveal a high antioxidant activity and a good in silico pharmacokinetic profile. The data obtained allowed us to select the most promising objects from the substances synthesized for further pharmacological screening for the presence of the antioxidant activity in vivo.

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