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Xenobiotic Biotransformation
Published in Robert G. Meeks, Steadman D. Harrison, Richard J. Bull, Hepatotoxicology, 2020
Aldehyde dehydrogenases (EC 1.2.1.3.) catalyze the oxidation of aldehydes to acids by using NAD as co-factor. The physiological substrates for the enzymes are unknown; the substrate specificity is broad. Classical substrates include acetaldehyde, formaldehyde, and glycolaldehyde, which are the biotransformation products of ethanol, methanol, and ethylene glycol, respectively. The enzymes are present in all organs and in cytosol, mitochondria and microsomes. Liver has the highest activity, but kidney also possesses high activity. The enzymes exist as several isozymes within the cytosolic, mitochrondrial, and microsomal compartments. One cytosolic isozyme is specific for the oxidation of formaldehyde complexed with glutathione and is referred to as formaldehyde dehydrogenase. Additional isozymes within the cytosol are differentiated by selective induction with PB or TCDD and 3-MC. The isozyme induced by TCDD and 3-MC has received special study due to its increased activity in tumor cells [see Marselos and Lindahl (1988)]. Since acetaldehyde is preferentially oxidized in mitochondria, an isozyme for its oxidation may be localized in these structures. Additional mitochrondrial isozymes can be differentiated by selective inhibition with the prototype aldehyde dehydrogenase inhibitor, disulfiram.
Alcohols and Aldehydes
Published in Frank A. Barile, Barile’s Clinical Toxicology, 2019
Formaldehyde can enter the body by inhalation, ingestion, or skin contact. Formaldehyde is readily absorbed via the respiratory and GI routes. Dermal absorption of formaldehyde appears to be very slight. In the systemic circulation, formaldehyde (CH2O) is rapidly metabolized to formate (CHOOH) by a glutathione-dependent formaldehyde dehydrogenase (ALDH), the product of which is further converted to carbon dioxide and water as described in Section 24.2.1.
Tissue Glutathione
Published in Robert A. Greenwald, CRC Handbook of Methods for Oxygen Radical Research, 2018
There are also methods in which GSH S-transferases are used.13,14 Other enzymatic assays which are based on the requirement of GSH as a cofactor include methods in which maleylpyruvate isomerase or formaldehyde dehydrogenase are used.15,16 A recycling assay using GSSG reductase17-19 which offers much higher sensitivity, will be described below.
Formaldehyde toxicity reports from in vitro and in vivo studies: a review and updated data
Published in Drug and Chemical Toxicology, 2022
Letícia Bernardini, Eduardo Barbosa, Mariele Feiffer Charão, Natália Brucker
In the human body, due to its water solubility and reactivity, FA could rapidly be diffused in many organs and tissues (Liu et al. 2018b, Leng et al. 2019). After its absorption, FA could spontaneously react with glutathione (GSH) to form hydroxymethylglutathione (HMGSH). The formaldehyde dehydrogenase (FDH) enzyme oxidizes HMGSH to S-formylglutathione (FGSH), which is metabolized by S-formylglutathione hydrolase, producing formate and regenerating reduced glutathione (Reingruber and Pontel 2018). Furthermore, FA also could be oxidized by aldehyde dehydrogenase (ALDH) along with cytochrome oxidase isoenzymes CYP450, including CYP2E1 (Dorokhov et al. 2018). This way, the produced formate can be eliminated in the urine in the form of formic acid, react with other biomolecules, or even be metabolized in carbon dioxide (Peteffi et al. 2016).
Formaldehyde as an alternative to antibiotics for treatment of refractory impetigo and other infectious skin diseases
Published in Expert Review of Anti-infective Therapy, 2019
Philip Nikolic, Poonam Mudgil, John Whitehall
Formaldehyde resistance has been reported in Pseudomonas species and in the family Enterobacteriaceae. In Enterobacteriaceae, resistance developed as a result of plasmid acquisition while in Pseudomonas, resistance is chromosomally located. The resistances are due to the presence of formaldehyde dehydrogenase enzymes. Nicotinamide adenine dinucleotide (NAD) dependent formaldehyde dehydrogenases are found in methanol-utilizing methylotrophic bacteria like Pseudomonas methanica and some other formaldehyde-utilizing bacteria like Pseudomonas aeruginosa. As these species utilize formaldehyde it is essential that they are capable of surviving its presence. Strains of Escherichia coli resistant to formaldehyde have also been commonly found and it is accepted that resistance to formaldehyde is most often found in gram-negative bacteria [40]. Formaldehyde resistant strains of S. aureus have not been reported in the literature.
The Activity of Class I-IV Alcohol Dehydrogenase Isoenzymes and Aldehyde Dehydrogenase in Bladder Cancer Cells
Published in Cancer Investigation, 2018
Karolina Orywal, Wojciech Jelski, Tadeusz Werel, Maciej Szmitkowski
We found statistically significant increase in isoenzyme class III of ADH activity in bladder cancer cells in comparison to histologically unchanged bladder tissue. It is interesting that the activity of ADH III was significantly higher only in high-grade bladder cancer group compared to controls. Class III alcohol dehydrogenase (χχ) is found in every tissue and is encoded by ADH3 loci. This isoenzyme has the same structure and kinetic properties as glutathione-dependent formaldehyde dehydrogenase. Isoenzymes of class III reveal a high affinity for endogenous long-chain alcohols and aldehydes, but its main role is participation in the catabolism of formaldehyde, produced after methanol poisoning (23). The similar findings was presented by Jelski et al. in the pancreatic cancer. They showed that in the cells of pancreatic cancer, there was significantly elevated activity of ADH isoenzyme III in comparison to healthy tissue (24). ADH III participates mainly in metabolism of endogenous long-chain alcohols and also aldehydes produce during lipid metabolism and catalyzes the oxidation of S-hydroxymethylglutathione. Disturbances in ADH III activity may lead to depletion of glutathione, which is a strong antioxidant compound responding for maintenance of redox state in cells. The consequence of decreased glutathione concentration may be generation of reactive oxygen species and induction of oxidative stress leading to cancer development.