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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).
Trigonella foenum-graecum L.
Published in Dilip Ghosh, Prasad Thakurdesai, Fenugreek, 2022
G. Sindhu, Chithra K. Pushpan, A. Helen
Bioactive compounds isolated from the leaves and seeds have been studied for their activity. Diosgenin has been widely studied for its vasoprotective effects. Fenugreek seed flour and diosgenin were studied for their ability to protect endothelial dysfunction in rat models. The animals were supplemented with fenugreek seed flour and diosgenin along with their diet in varying concentrations for a period of 6 weeks. The study showed protection against endothelial damage and antioxidant properties in both the fenugreek flour and diosgenin with fenugreek flour showing comparatively increased protection. This is explained as a cumulative effect of other bioactive components in fenugreek other than diosgenin. Their study shows an improvement in glutathione reductase activity, oxidized and reduced glutathione which is indicative of its ability to regulate the redox balance in blood, which can contribute to vasoprotective effects (Szabó et al., 2018). The vasoprotective effect by regulating lipid metabolism and molecules involved in cell signaling involved in vascular homeostasis has been studied with diosgenin (Manivannan et al., 2013).
Platelet Disorders Douglas Triplett
Published in Genesio Murano, Rodger L. Bick, Basic Concepts of Hemostasis and Thrombosis, 2019
Studies of platelet enzymes in various biochemical pathways have failed to reveal consistent abnormalities. Deficiencies of glyceraldehyde 3-phosphodehydrogenase and pyruvate kinase have been demonstrated, as has a deficiency of glutathione peroxidase.93 Another abnormality in the glutathione pathway has also been described, a reduction of the glutathione reductase activity.94 These findings suggest that the ability of the thrombasthenic platelet to withstand oxidative stress is deficient.
Purification and characterisation of glutathione reductase from scorpionfish (scorpaena porcus) and investigation of heavy metal ions inhibition
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2023
Glutathione reductase (EC 1.8.1.7; GR), a major enzyme in glutathione metabolism, is required for the maintenance of the reduced form of cellular glutathione, which is strongly nucleophilic for many reactive electrophiles10,11. The flavin enzyme GR acts as an antioxidant to protect cells from oxidative stress by reducing glutathione disulphide (GSSG) to its reduced form (GSH)12. It has an important role in the drug and detoxification mechanisms especially in the liver. This is due to the cytochrome P-450 system found in liver microsomes, which provides detoxifying events13. Maintaining the GSH/GSSG ratio in the cell environment is one of the most important known targets of the GR enzyme-catalysed reactions14. Glutathione reductase is involved in the reduction-oxidation of intracellular glutathione for GSSG, which is generated through the detoxification of hydroperoxides and reduction of some other chemicals catalysed by glutathione perdoxidase15. The NADP+ dependent malate dehydrogenase and pentose phosphate pathways provide the NADPH needed in this catalytic process16,17. NADPH, a key product of the pentose phosphate cycle, is employed extensively in reductive biosynthesis. Furthermore, it aids in the protection of the cell against oxidative damage9.
A comprehensive proteomics analysis of the response of Pseudomonas aeruginosa to nanoceria cytotoxicity
Published in Nanotoxicology, 2023
Lidija Izrael Živković, Nico Hüttmann, Vanessa Susevski, Ana Medić, Vladimir Beškoski, Maxim V. Berezovski, Zoran Minić, Ljiljana Živković, Ivanka Karadžić
The downregulation of glutathione (GSH)-related enzymes (glutathione peroxidase and hydrolase), (Table 1) and unaltered levels of glutathione reductase (Supplementary Table 1) is intriguing, since disturbed redox homeostasis usually increases the amount of glutathione and related enzymes in the cell. The reduction potentials of pyocyanin and GSH point out their direct reaction, as well as the reaction between GSH and ROS induced by pyocyanin, both depleting intracellular GSH levels. This is only partially reimbursed by glutathione reductase, leaving cells deficient in GSH and more sensitive to redox stress (Das et al. 2017). Interestingly, the downregulation of polyhydroxyalkanoate synthesis protein, PhaF, was found. This enzyme can cause lowered synthesis of polyhydroxyalkanoates, which function as a reducing equivalent pool to maintain cellular redox balance (Ayub, Tribelli, and Lopez 2009). The lack of polyhydroxylalkanoate implies altered redox homeostasis and fatty acid biosynthesis, as found in this study. Upregulation of flavoprotein pyridine nucleotide transhydrogenase, responsible for the conversion of NADPH to NADH, and ferredoxin-NADP reductase (Table 1), was observed, aligning with enhanced superoxide radical production.
Role of geraniol against lead acetate-mediated hepatic damage and their interaction with liver carboxylesterase activity in rats
Published in Archives of Physiology and Biochemistry, 2018
Ahmet Ozkaya, Zafer Sahin, Muslum Kuzu, Yavuz Selim Saglam, Mustafa Ozkaraca, Mirac Uckun, Ertan Yologlu, Veysel Comakli, Ramazan Demirdag, Semra Yologlu
For the determining GST activity, first 20 mM 1-chloro-2,4-dinitrobenzene (CDNB) was prepared in 96% ethanol, and this solution was used as the substrate. Reductive glutathione (0.002 M) was used as the cofactor in the reaction (Habig et al.1974). Briefly, 10 μL of the supernatant, 100 μL of phosphate buffer (0.1 M, pH 6.5) + 100 μL of GSH mixture and finally 10 μL of CDNB were transferred into the wells of the microplate. After this process, the well plates were placed in the microplate reader system and the change in absorbance was recorded at 344 nm for 2 min at 25 °C. Specific GST activity was calculated as nmol/min/mg protein. Measurement of glutathione reductase (GR) activity was determined by the modified method (Carlberg and Mannervik 1985).