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The Biosphere
Published in Stanley E. Manahan, Environmental Chemistry, 2022
Xenobiotic species may be metabolized in many body tissues and organs. As part of the body's defense against the entry of xenobiotic species, the most prominent sites of xenobiotic metabolism are those associated with entry into the body, such as the skin and lungs. The gut wall through which xenobiotic species enter the body from the gastrointestinal tract is also a site of significant xenobiotic compound metabolism. The liver is of particular significance because materials entering systemic circulation from the gastrointestinal tract must first traverse the liver.
The Biosphere: Environmental Biochemistry
Published in Stanley Manahan, Environmental Chemistry, 2017
Xenobiotic species may be metabolized in many body tissues and organs. As part of the body’s defense against the entry of xenobiotic species, the most prominent sites of xenobiotic metabolism are those associated with entry into the body, such as the skin and lungs. The gut wall through which xenobiotic species enter the body from the gastrointestinal tract is also a site of significant xenobiotic compound metabolism. The liver is of particular significance because materials entering systemic circulation from the gastrointestinal tract must first traverse the liver.
Recent Advancements in Microbial Degradation of Xenobiotics by Using Proteomics Approaches
Published in Vineet Kumar, Vinod Kumar Garg, Sunil Kumar, Jayanta Kumar Biswas, Omics for Environmental Engineering and Microbiology Systems, 2023
Neha Sharma, Smriti Shukla, Kartikeya Shukla, Ajit Varma, Vineet Kumar, Menaka Devi Salam, Arti Mishra
Xenobiotic compounds are very hazardous. They affect lower as well as higher eukaryotes. Various diseases such as skin diseases and cancer are caused by prolonged exposure to them. Their persistent nature and increasing concentration in the environment have raised concerns for their harmful effects (Crinnion et al. 2010; Kim et al. 2013; Embrandiri et al. 2016; Tsaboula et al. 2016; Dhakal et al. 2017). Xenobiotics are non-degradable, and they remain persistent in the environment because of their bioaccumulation nature. Bioaccumulation is the process by which any non-degradable substances get accumulated and may enter food chain, leading to disturbance of metabolic activities (Bharadwaj et al. 2018). For example, an increase in minute levels of DDT can disturb the metabolism of fish, birds, and mammals. Xenobiotics can exert toxic as well as late effects. Late effects include congenital defects, cancer, and allergies. In animals, the increasing level of DDT leads to premature birth and, reduction in semen quality and duration of lactation in human beings. DDT is a human carcinogen. It has the potential to cause pancreatic cancer. It has been revealed by experimental studies on rats that it causes hepatotoxicity, cell necrosis, hyperplasia, hypertrophy, and increased activity of serum liver enzymes (Kostka et al. 1996). Endosulfan is another organochlorine insecticide that kills a wide range of arthropod pests and insects. A prolonged contact with this pesticide can cause congenital birth defects, immunosuppression, neurological disorders, mental retardation, chromosomal abnormalities, and amnesia. Endosulfan is made up of two isomers: α and β. The latter is more harmful to insects as well as mammals. It is highly toxic. In animal studies, the use of endosulfan has shown reduced count of spermatozoa and testosterone inhibition.
Another target organ?
Published in Archives of Environmental & Occupational Health, 2019
The route of exposure of most obvious concern is clearly oral and there are an abundance of ways that a food or water contaminant, a food additive or residue, or an inhaled and aspirated material might reach and affect the gut microbiome. Of course, they would have to get through the stomach and its acidity first. The stomach is normally almost sterile (in adults), except in serious disease and Helicobacter pylori infection. Once beyond the pylorus, however, there is little to impede further growth and the reservoir for the microbiome appears to be the cecum, a sac at the transition from the small intestine to the colon, where the appendix lies. Many xenobiotics are metabolized in the liver and excreted in bile, both organic compounds and metals. Many of these are of toxicological interest, such as organochlorine compounds and mercury. Iron, important in the inflammatory response, has long been known to be concentrated in bile.4 The common bile duct carries the secreted bile to the duodenum, the first part of the small intestine, just downstream from this transition. At this point, xenobiotics concentrated from the circulation meet the microbiome by a route independent of ingestion.
Regulation of cytochrome P450 expression by microRNAs and long noncoding RNAs: Epigenetic mechanisms in environmental toxicology and carcinogenesis
Published in Journal of Environmental Science and Health, Part C, 2019
Dongying Li, William H. Tolleson, Dianke Yu, Si Chen, Lei Guo, Wenming Xiao, Weida Tong, Baitang Ning
Humans are exposed throughout their lives to potentially harmful naturally-occurring and man-made organic compounds present in the air, water, and diet. Hazardous xenobiotic (Greek, xenos – stranger; bios – life) environmental chemicals are recognized as important risk factors for cancers and for a variety of other human diseases. Well known examples include the increased risk for lung cancer in humans associated with exposure to nitrosamines and other carcinogens present in tobacco smoke, exposure to the industrial chemical benzene that increases the risk for leukemia, and dietary exposure to aflatoxins that is associated with increased risk for liver cancer.1
Plant pharmacology: Insights into in-planta kinetic and dynamic processes of xenobiotics
Published in Critical Reviews in Environmental Science and Technology, 2022
Tomer Malchi, Sara Eyal, Henryk Czosnek, Moshe Shenker, Benny Chefetz
Plant pharmacology offers a comparative understanding of the interaction of xenobiotic compounds with plants and animals. For the premise of the following discussion, pharmacology is defined as the study of the interactions between exogenous chemicals and living systems and the manner in which the functions of living systems are affected by exogenous chemical agents (Rang et al., 2019). Xenobiotics are substances that are foreign to the biological system and include natural or synthetic chemicals, medicinal drugs, agricultural and industrial chemicals, environmental contaminants and other exogenous substances (Howland, 2015). The term drug or pharmaceutical refers to a xenobiotic chemical substance to which organisms are exposed and that can potentially cause a biochemical or physiological effect at the cell, tissue, organ, or organism level (Buxton & Benet, 2013). Pharmaceutical interactions are distinguished into: “what the biological system does to the drug,” i.e., pharmacokinetics, and “what the drug does to the biological systems,” i.e., pharmacodynamics (Goodman et al., 2000). Pharmacokinetics is the study of the effects of biological systems to drugs in terms of drug absorption, distribution, metabolism and elimination (ADME). Pharmacodynamics studies the effects of a drug to the biological system and its mechanism of action, elucidating the relationship between drug concentration at the site of action and its biochemical or physiological effects. In classic pharmacology, pharmacokinetics and pharmacodynamics are two sub-divisions of a conceptual model that enables quantitative modeling and prediction of drug effects on a living system. In understanding the different processes that translate into dose-response relationships, it is evident that a compound's kinetics and dynamics are interrelated processes (Shargel et al., 2012).