This Key Event Relationship is licensed under the Creative Commons BY-SA license. This license allows reusers to distribute, remix, adapt, and build upon the material in any medium or format, so long as attribution is given to the creator. The license allows for commercial use. If you remix, adapt, or build upon the material, you must license the modified material under identical terms.
Conjugation, GSH leads to Depletion, GSH
Key Event Relationship Overview
AOPs Referencing Relationship
|AOP Name||Adjacency||Weight of Evidence||Quantitative Understanding||Point of Contact||Author Status||OECD Status|
|Glutathione conjugation leading to reproductive dysfunction via oxidative stress||adjacent||High||High||Leonardo Vieira (send email)||Under Development: Contributions and Comments Welcome|
Life Stage Applicability
|All life stages||High|
Key Event Relationship Description
Evidence Collection Strategy
Evidence Supporting this KER
GSH is an antioxidant generated in various kinds of cells, however, in vertebrates, this takes place mainly in liver cells, from where it is exported to other cell types (Lu 2013). Around 85% of free GSH is found in the cytoplasm, from where it is distributed to organelles such as mitochondria, which stores approximately 10% of the total GSH content, endoplasmic reticulum and extracellular space (Lu 2013; Aquilano, Baldelli, and Ciriolo 2014). Depletion of free GSH content happens because of the sulfhydryl group of the cysteine residue of this tripeptide reacts with xenobiotics during detoxification process, producing conjugates, which are secreted directly into the bile or converted to mercapturic acids and excreted into the urine, as well as due to the reaction with other reactive species as ROS. Nevertheless, unlike what happens to glycine and glutamate residues with oxidized glutathione (GSSG), which are recycled respectively from detoxification of xenobiotics and ROS-mediated oxidation, the cysteine molecule from GSH is excreted from the organism as a byproduct conjugated to the toxic molecule, causing, thereby, reduction of cellular levels of this limiting amino acid for the tripeptide production. In this way, restoration of regular intracellular GSH levels, via de novo synthesis and still from the reaction of reduction of oxidized glutathione (GSSG) ends up being hampered (X. Li 2009; Lushchak 2012; Gupta 2016; Aquilano, Baldelli, and Ciriolo 2014) and GSH levels are, consequently, depleted.
Uncertainties and Inconsistencies
Known modulating factors
|Modulating Factor (MF)||MF Specification||Effect(s) on the KER||Reference(s)|
|antioxidant||biflavonone-kolaviron||prevent GSH depletion||Abarikwu, Farombi, and Pant 2011|
|antioxidant||vitamin E||prevent GSH depletion||Singh, Sandhir, and Kiran 2010|
Velocity of conjugation, however, depends on the kind of GST involved and on the chemical, as well as the organism in which it takes place. For instance, the ATZ-GSH conjugate formed in GSTs from zebrafish embryos works in a time-dependent manner, although conjugation in the microsomal GST increased linearly by a factor of 23 up to 12 h of incubation time, whereas in the soluble GST the conversion rate increased more slowly and was higher by a factor of 5.8 after 24 h of incubation time than that at start (Wiegand et al. 2001). In rats, the estimated GSH conjugation rate constant with ATZ was 0.53 L/mmol/h, a value comparable to that for other chemicals that are largely conjugated by GSTs, even so less than known depleters such as ethylene dichloride (1.2 L/mmol/h) and allyl chloride (9.0 L/mmol/h). Although ATZ is mostly metabolized by GSH, the model estimated that 50% depletion of GSH is predicted to occur, but only after three daily doses of 500 mg ATZ/Kg (McMullin et al. 2003).
In humans, intrahepatic glutathione concentration is predicted to be the lowest one, due to conjugation to the reactive intermediate NAPQI, at 6 h after 2 g of intravenous (IV) infusion administration of paracetamol and then to recover slowly. In addition, it responds in a time-dependent way. However, concentrations of glutathione were predicted to be markedly and progressively depleted when patients had an initial 2 g dose and then 1 g dose every 6 h (Geenen et al. 2013).
(Hughes, Miller, and Swamidass 2015), for example, constructed a model to predict the GSH reactivity to 1213 molecules and determined the percent depletion of GSH after 15 min incubation with each molecule. In this context, such a model can be easily used for investigation and initial selection of molecules that might impair fertility.
Known Feedforward/Feedback loops influencing this KER
Domain of Applicability
Considering the empirical domain of the evidence, the GSH conjugation leading to GSH depletion is known to occur in all vertebrates animals, but, based on scientific reasoning, it can also occur in eukaryotic organisms in general. It can be measured at any stage of life and in both male and female species.
Lu, Shelly C. 2013. “Glutathione Synthesis.” Biochimica et Biophysica Acta 1830 (5): 3143–53.
Aquilano, Katia, Sara Baldelli, and Maria R. Ciriolo. 2014. “Glutathione: New Roles in Redox Signaling for an Old Antioxidant.” Frontiers in Pharmacology 5 (August): 196.
Li, Xianchun. 2009. “Glutathione and Glutathione-S-Transferase in Detoxification Mechanisms.” In General, Applied and Systems Toxicology. Chichester, UK: John Wiley & Sons, Ltd. https://doi.org/10.1002/9780470744307.gat166.
Lushchak, Volodymyr I. 2012. “Glutathione Homeostasis and Functions: Potential Targets for Medical Interventions.” Journal of Amino Acids 2012 (February): 736837.
Gupta, P. K. 2016. “Chapter 8 - Biotransformation.” In Fundamentals of Toxicology, edited by P. K. Gupta, 73–85. Academic Press.
Egaas, E., J. U. Skaare, N. O. Svendsen, M. Sandvik, J. G. Falls, W. C. Dauterman, T. K. Collier, and J. Netland. 1993. “A Comparative Study of Effects of Atrazine on Xenobiotic Metabolizing Enzymes in Fish and Insect, and of the Invitro Phase II Atrazine Metabolism in Some Fish, Insects, Mammals and One Plant Species.” Comparative Biochemistry and Physiology. Part C, Pharmacology, Toxicology & Endocrinology 106 (1): 141–49.
Wiegand, C., E. Krause, C. Steinberg, and S. Pflugmacher. 2001. “Toxicokinetics of Atrazine in Embryos of the Zebrafish (Danio Rerio).” Ecotoxicology and Environmental Safety 49 (3): 199–205.
Elia, A. C., W. T. Waller, and S. J. Norton. 2002. “Biochemical Responses of Bluegill Sunfish (Lepomis Macrochirus, Rafinesque) to Atrazine Induced Oxidative Stress.” Bulletin of Environmental Contamination and Toxicology 68 (6): 809–16.
Abel, Erika L., Shaun M. Opp, Christophe L. M. J. Verlinde, Theo K. Bammler, and David L. Eaton. 2004. “Characterization of Atrazine Biotransformation by Human and Murine Glutathione S-Transferases.” Toxicological Sciences: An Official Journal of the Society of Toxicology 80 (2): 230–38.
McMullin, Tami S., William H. Hanneman, Brian K. Cranmer, John D. Tessari, and Melvin E. Andersen. 2007. “Oral Absorption and Oxidative Metabolism of Atrazine in Rats Evaluated by Physiological Modeling Approaches.” Toxicology 240 (1-2): 1–14.
LeBlanc, André, and Lekha Sleno. 2011. “Atrazine Metabolite Screening in Human Microsomes: Detection of Novel Reactive Metabolites and Glutathione Adducts by LC-MS.” Chemical Research in Toxicology 24 (3): 329–39.
Combes, B., and B. Backof. 1982. “Effect of Diethyl Maleate on the Biliary Excretion Rate of Infused Sulfobromophthalein-Glutathione.” Biochemical Pharmacology 31 (16): 2669–74.
Kubal, G., D. J. Meyer, R. E. Norman, and P. J. Sadler. 1995. “Investigations of Glutathione Conjugation in Vitro by 1H NMR Spectroscopy. Uncatalyzed and Glutathione Transferase-Catalyzed Reactions.” Chemical Research in Toxicology 8 (5): 780–91.
Stricks, W., and I. M. Kolthoff. 1953. “Reactions between Mercuric Mercury and Cysteine and Glutathione. Apparent Dissociation Constants, Heats and Entropies of Formation of Various Forms of Mercuric Mercapto-Cysteine and -Glutathione.” Journal of the American Chemical Society 75 (22): 5673–81.
Wang, Shengchen, Qiaojian Zhang, Shufang Zheng, Menghao Chen, Fuqing Zhao, and Shiwen Xu. 2019. “Atrazine Exposure Triggers Common Carp Neutrophil Apoptosis via the CYP450s/ROS Pathway.” Fish & Shellfish Immunology 84 (January): 551–57.
Santos, Thais G., and Cláudia B. R. Martinez. 2012. “Atrazine Promotes Biochemical Changes and DNA Damage in a Neotropical Fish Species.” Chemosphere 89 (9): 1118–25.
Mela, M., I. C. Guiloski, H. B. Doria, M. A. F. Randi, C. A. de Oliveira Ribeiro, L. Pereira, A. C. Maraschi, V. Prodocimo, C. A. Freire, and H. C. Silva de Assis. 2013. “Effects of the Herbicide Atrazine in Neotropical Catfish (Rhamdia Quelen).” Ecotoxicology and Environmental Safety 93 (July): 13–21.
Adeyemi, Joseph A., Airton da Cunha Martins-Junior, and Fernando Barbosa Jr. 2015. “Teratogenicity, Genotoxicity and Oxidative Stress in Zebrafish Embryos (Danio Rerio) Co-Exposed to Arsenic and Atrazine.” Comparative Biochemistry and Physiology. Toxicology & Pharmacology: CBP 172-173 (April): 7–12.
Jin, Yuanxiang, Xiangxiang Zhang, Linjun Shu, Lifang Chen, Liwei Sun, Haifeng Qian, Weiping Liu, and Zhengwei Fu. 2010a. “Oxidative Stress Response and Gene Expression with Atrazine Exposure in Adult Female Zebrafish (Danio Rerio).” Chemosphere 78 (7): 846–52.
Toughan, Hosam, Samah R. Khalil, Ashraf Ahmed El-Ghoneimy, Ashraf Awad, and A. Sh Seddek. 2018. “Effect of Dietary Supplementation with Spirulina Platensis on Atrazine-Induced Oxidative Stress- Mediated Hepatic Damage and Inflammation in the Common Carp (Cyprinus Carpio L.).” Ecotoxicology and Environmental Safety 149 (March): 135–42.
Ahmed, Yasmine H., Huda O. AbuBakr, Ismail M. Ahmad, and Zainab Sabry Othman Ahmed. 2022. “Histopathological, Immunohistochemical, And Molecular Alterations In Brain Tissue And Submandibular Salivary Gland Of Atrazine-Induced Toxicity In Male Rats.” Environmental Science and Pollution Research International 29 (20): 30697–711.
Song, Yang, Zhen Chao Jia, Jin Yao Chen, Jun Xiang Hu, and Li Shi Zhang. 2014. “Toxic Effects of Atrazine on Reproductive System of Male Rats.” Biomedical and Environmental Sciences: BES 27 (4): 281–88.
Kalia, Sumiti, and M. P. Bansal. 2008. “Diethyl Maleate-Induced Oxidative Stress Leads to Testicular Germ Cell Apoptosis Involving Bax and Bcl-2.” Journal of Biochemical and Molecular Toxicology 22 (6): 371–81.
Kaur, Parminder, Sumiti Kalia, and Mohinder P. Bansal. 2006. “Effect of Diethyl Maleate Induced Oxidative Stress on Male Reproductive Activity in Mice: Redox Active Enzymes and Transcription Factors Expression.” Molecular and Cellular Biochemistry 291 (1-2): 55–61.
Zhang, Qun-Fang, Ying-Wen Li, Zhi-Hao Liu, and Qi-Liang Chen. 2016. “Reproductive Toxicity of Inorganic Mercury Exposure in Adult Zebrafish: Histological Damage, Oxidative Stress, and Alterations of Sex Hormone and Gene Expression in the Hypothalamic-Pituitary-Gonadal Axis.” Aquatic Toxicology 177 (August): 417–24.
El-Desoky, Gaber E., Samir A. Bashandy, Ibrahim M. Alhazza, Zeid A. Al-Othman, Mourad A. M. Aboul-Soud, and Kareem Yusuf. 2013. “Improvement of Mercuric Chloride-Induced Testis Injuries and Sperm Quality Deteriorations by Spirulina Platensis in Rats.” PloS One 8 (3): e59177.
Ma, Yan, Mingkun Zhu, Liping Miao, Xiaoyun Zhang, Xinyang Dong, and Xiaoting Zou. 2018. “Mercuric Chloride Induced Ovarian Oxidative Stress by Suppressing Nrf2-Keap1 Signal Pathway and Its Downstream Genes in Laying Hens.” Biological Trace Element Research 185 (1): 185–96.
D’Souza, R. W., and M. E. Andersen. 1988. “Physiologically Based Pharmacokinetic Model for Vinylidene Chloride.” Toxicology and Applied Pharmacology 95 (2): 230–40.
D’Souza, R. W., W. R. Francis, and M. E. Andersen. 1988. “Physiological Model for Tissue Glutathione Depletion and Increased Resynthesis after Ethylene Dichloride Exposure.” The Journal of Pharmacology and Experimental Therapeutics 245 (2): 563–68.
Mulder, G. J., and S. Ouwerkerk-Mahadevan. 1997. “Modulation of Glutathione Conjugation in Vivo: How to Decrease Glutathione Conjugation in Vivo or in Intact Cellular Systems in Vitro.” Chemico-Biological Interactions 105 (1): 17–34.
Fennell, T. R., and C. D. Brown. 2001. “A Physiologically Based Pharmacokinetic Model for Ethylene Oxide in Mouse, Rat, and Human.” Toxicology and Applied Pharmacology 173 (3): 161–75.
Spahiu, Linda, Johan Ålander, Astrid Ottosson-Wadlund, Richard Svensson, Carina Lehmer, Richard N. Armstrong, and Ralf Morgenstern. 2017a. “Global Kinetic Mechanism of Microsomal Glutathione Transferase 1 and Insights into Dynamic Enzyme Activation.” Biochemistry 56 (24): 3089–98.
Csanády, G. A., P. E. Kreuzer, C. Baur, and J. G. Filser. 1996. “A Physiological Toxicokinetic Model for 1,3-Butadiene in Rodents and Man: Blood Concentrations of 1,3-Butadiene, Its Metabolically Formed Epoxides, and of Haemoglobin Adducts--Relevance of Glutathione Depletion.” Toxicology 113 (1-3): 300–305.
Morgenstern, R., R. Svensson, B. A. Bernat, and R. N. Armstrong. 2001. “Kinetic Analysis of the Slow Ionization of Glutathione by Microsomal Glutathione Transferase MGST1.” Biochemistry 40 (11): 3378–84.
Mayer, Robert J., and Armin R. Ofial. 2019. “Nucleophilicity of Glutathione: A Link to Michael Acceptor Reactivities.” Angewandte Chemie 58 (49): 17704–8.
McMullin, Tami, Jill Brzezicki, Brian Cranmer, John Tessari, and Melvin Andersen. 2003. “Pharmacokinetic Modeling of Disposition and Time-Course Studies With [ 14 C]Atrazine.” Journal of Toxicology and Environmental Health. Part A 66 (10): 941–64.
Geenen, Suzanne, James W. T. Yates, J. Gerry Kenna, Frederic Y. Bois, Ian D. Wilson, and Hans V. Westerhoff. 2013. “Multiscale Modelling Approach Combining a Kinetic Model of Glutathione Metabolism with PBPK Models of Paracetamol and the Potential Glutathione-Depletion Biomarkers Ophthalmic Acid and 5-Oxoproline in Humans and Rats.” Integrative Biology: Quantitative Biosciences from Nano to Macro 5 (6): 877–88.
Hughes, Tyler B., Grover P. Miller, and S. Joshua Swamidass. 2015. “Site of Reactivity Models Predict Molecular Reactivity of Diverse Chemicals with Glutathione.” Chemical Research in Toxicology 28 (4): 797–809.
Abarikwu, S. O., E. O. Farombi, and A. B. Pant. 2011. “Biflavanone-Kolaviron Protects Human Dopaminergic SH-SY5Y Cells against Atrazine Induced Toxic Insult.” Toxicology in Vitro: An International Journal Published in Association with BIBRA 25 (4): 848–58.
Singh, Mohan, Rajat Sandhir, and Ravi Kiran. 2010. “Oxidative Stress Induced by Atrazine in Rat Erythrocytes: Mitigating Effect of Vitamin E.” Toxicology Mechanisms and Methods 20 (3): 119–26.