Explore chapters and articles related to this topic
Free Radicals and Antioxidants
Published in Chuong Pham-Huy, Bruno Pham Huy, Food and Lifestyle in Health and Disease, 2022
Chuong Pham-Huy, Bruno Pham Huy
Glutathione (GSH) is an endogenous antioxidant peptide composed of three amino acids: cysteine, glycine, and glutamate; and can be found in every cell (except in epithelial cells) of the human body (82). Its antioxidant properties are due to the thiol group present in its cysteine moiety which is a reducing agent and can be reversibly oxidized and reduced (82). In cells, glutathione is maintained in the reduced form by the enzyme glutathione reductase and in turn reduces other metabolites and enzyme systems as well as reacting directly with oxidants (82). Due to its high concentration and central role in maintaining the cell’s redox state, glutathione is one of the most important cellular antioxidants (82). GSH has a central role in biotransformation and elimination of xenobiotics and protects cells against oxidative stress. It is not required in the diet, but it is also present in vegetable and animal foods and can be partially absorbed by the human small intestine (22).
Eichhornia crassipes: Shedding Light on its Chemical Composition, Biological Activities and Industrial Uses
Published in Mahendra Rai, Shandesh Bhattarai, Chistiane M. Feitosa, Ethnopharmacology of Wild Plants, 2021
Fadia S. Youssef, Noor H. Aysa, Mohamed L. Ashour
A thiol group-containing compound acts as a protectant that is commonly adopted in the chemistry of peptides and proteins as well. Thus, in biochemistry, during the assessment of heavy metal content in peptides and proteins, it is usually added in large amounts that differ according to the prepared protein. The presence of thiol-containing compounds is perfectly used to determine the heavy metal bio-concentration by water hyacinth (Ding et al. 1994).
Role of Metabolism in Chemically Induced Nephrotoxicity
Published in Robin S. Goldstein, Mechanisms of Injury in Renal Disease and Toxicity, 2020
Monks et al. (1988) synthesized 6-bromo-2,5-dihydroxy-thiophenol, a putative metabolite of 2-bromohydroquinone-GSH conjugates, and found that this compound is a potent nephrotoxicant. According to this scheme, GSH S-conjugates of 2-bromohydroquinone are metabolized by the mercapturate pathway and are processed to release thiol metabolites (Figure 9). Study of the toxicity of various analogs, however, pointed more towards the quinone moiety, rather than the thiol group, in the mechanism of toxicity. Thus, although GSH conjugation and further metabolism by the mercapturate or cysteine conjugate β-lyase pathway (see below) occurs, they are not critical elements in the mechanism of 2-bromohydroquinone-induced nephrotoxicity (Monks et al., 1985). In support of this conclusion, other studies with 1,4-benzoquinone (Lau et al., 1988) and menadione (2-methyl-1,4-naphthoquinone) (Redegeld et al., 1991) indicate a role for GSH conjugation, but not formation of a reactive thiol metabolite in nephrotoxicity. The physiological significance of the GSH conjugation pathway in quinone-induced nephrotoxicity is therefore still unresolved.
Relationship between thiol, disulphide volume and contrast-induced nephropathy in acute coronary syndrome patients treated with percutaneous coronary intervention
Published in Scandinavian Journal of Clinical and Laboratory Investigation, 2021
Deniz Elcik, Saban Kelesoglu, Yucel Yilmaz, Zeki Cetinkaya, Joma Sulaiman, Ridvan Yurt, Salim Neselioglu, Ozcan Erel, Mehmet Tugrul Inanc, Abdurrahman Oguzhan
The samples for thiols were centrifuged at 1500 g for 10 min. The plasma was stored at −80 °C and all samples were processed simultaneously. Thiol group levels and thiol/disulphide homeostasis was measured as defined by Erel et al [15]. Serum natural thiol and total thiol levels were measured spectrophotometrically. Initially, serum natural thiol levels were measured after the reaction with 5, 5′-dithiobis-2-nitrobenzoic acid (DTNB) without any treatment. Second, to measure total thiol levels, dynamic disulfide bonds in serum samples were reduced using sodium borohydride (NaBH4) to form free functional thiol groups. Formaldehyde was then used to completely remove unused NaBH4, and total thiol groups, including both reduced and natural ones, were measured following reaction with DTNB. Since the reduction of a disulfide bond produces two distinct thiol groups, the number of dynamic disulfide bonds was calculated by determining half the difference between the total thiol and natural thiol.
Protective effect of aminoguanidine against lipopolysaccharide-induced hepatotoxicity and liver dysfunction in rat
Published in Drug and Chemical Toxicology, 2021
Farimah Beheshti, Mahmoud Hosseini, Mehdi Taheri Sarvtin, Ali Kamali, Akbar Anaeigoudari
The MDA concentration was determined using thiobarbituric acid (TBA) as a reagent of MDA. In the presence of TBA, MDA produces a red complex with maximal absorbance at 535 nm (Anaeigoudari et al. 2015). To determine the content of total thiol group, we used DTNB (2,2′-dinitro-5,5′ dithiodibenzoic acid) as a reagent (Beheshti et al. 2017). Reaction of DTNB with the SH group of total thiol leads to the appearance of yellow complex which has a peak absorbance at 412 nm. To determine the concentration of NO metabolites, we used Griess method (Schulz et al. 1999). At first, 100 µl supernatant was added to the Griess reagents. Then, supernatant mixed with reagents were transferred to a 96-well flat-bottomed micro-plate. After reading the absorbance at 520 nm, the values were computed using a standard calibration plots (Hosseini et al. 2018).
Nanosized silver, but not titanium dioxide or zinc oxide, enhances oxidative stress and inflammatory response by inducing 5-HETE activation in THP-1 cells
Published in Nanotoxicology, 2020
Wing-Lam Poon, Jetty Chung-Yung Lee, Kin Sum Leung, Harri Alenius, Hani El-Nezami, Piia Karisola
GSH is the largest source of low-molecular-weight thiol (R-SH), and its oxidized and reduced forms compose the major redox pair in animal cells, playing an important role in anti-oxidant defense (Wu et al. 2004). The thiol group offers an additional protection against metal stress as it can chelate reactive, free metal ions (Hernandez et al. 2015; Leung et al. 2013), and facilitate their excretion from the cell (Ballatori et al. 2009). GSH synthesis is largely dependent on the activity of its first rate-limiting step enzyme, glutamate-cysteine ligase (GCL, also known as gamma-glutamylcysteine synthetase), and is encoded by the two genes: GCLC (catalytic subunit) and GCLM (modifier subunit). Induction of this enzyme can be triggered at least by oxidant stress, inflammatory cytokines and heavy metals (Wu et al. 2004). In our current work, we found that cellular GSH in THP-1-differentiated macrophages was significantly increased by n-Ag with an elevated GCLC gene expression, implying incremental GSH synthesis and its subsequent accumulation in the cells during the 24 h of exposure. This is thought to be a response to defend against the increasing ROS production and/or the released toxic metal ions by the cell (Xu et al. 2014). These data are in line with many studies that show altered cellular GSH level together with the ROS production triggered by Ag NMs as reviewed by Cameron et al (Cameron et al. 2018).