Formaldehyde
William J. Rea, Kalpana D. Patel in Reversibility of Chronic Disease and Hypersensitivity, Volume 4, 2017
Formaldehyde is an aliphatic hydrocarbon that is usually derived from petroleum, but it can be generated naturally at low levels in humans. It is widely distributed in products and industry, with uses in commerce and the home. Formaldehyde may also arise from the degradation of volatile organic chemicals commonly found in indoor air. Formaldehyde is a common air contaminant in urban areas and usually accounts for about 50% of the total aldehydes in polluted air. According to the Toxics Release Inventory, in 1996, 21 million pounds of formaldehyde were released to the environment from 674 domestic manufacturing and processing facilities. Although source factors are the most important aspect of formaldehyde pollution, levels of emission are further influenced by several environmental variables, including fluctuations in indoor and outdoor temperature, humidity, and ventilation. Some chemically sensitive patients exhibit slow clearing rates, while others develop total anosmia to formaldehyde due to damage of the olfactory nerve.
Bimodal Reaction Sequences in Oxidation of Hydrogen and Organic Compounds with Dioxygen
Robert Bakhtchadjian in Bimodal Oxidation: Coupling of Heterogeneous and Homogeneous Reactions, 2019
This chapter covers some general problems of the oxidation process and focuses on the bimodal reaction sequences in the interaction of hydrogen and organic compounds of some major classes, such as hydrocarbons, alcohols, and aldehydes with dioxygen in the presence of different solid substances. It discusses reactivity of active oxygen species formed from dioxygen and, to the other intermediates formed from substrates in the fluid phases and on the surfaces of solid substances. The chapter also discusses the peculiarities of the mechanism and synergistic effects in bimodal oxidation by coupling homogeneous and heterogeneous constituents in a unified process. Both in the homogeneous and heterogeneous oxidation processes, the catalyst used must be cheap, stable, durable, easily separable from products, and its regeneration must be realizable by easy procedures. The chapter shows that limited reactivity of molecular oxygen in ordinary conditions related to its electronic structure.
Search of Active Site
Haruo Suzuki in How Enzymes Work, 2019
This chapter describes universal and easy ways to study on the active site: chemical modification and site-directed mutagenesis. The chemical modification may be useful to primary and pilot studies on the active site of enzyme. The concentration of the active enzyme-unit is proportional to the enzyme activity. Therefore, the enzyme was incubated with various concentrations of Phenylglyoxal for given times, then the enzyme activity was assayed to measure the concentration of the active enzyme. The active site carbonyl group reacts with substrate amine to change to the amino group, with a concomitant formation of the corresponding aldehyde. In amino acid residues in the enzyme proteins, functional groups are amino, carboxyl, sulfhydryl, hydroxyl, imidazole, and gunidino groups. Phenylhydrazine Chemical modification of carbonyl group is not included in works such as refs.
Increasing recognition of the importance of aldehyde oxidase in drug development and discovery
Published in Drug Metabolism Reviews, 2011
Enrico Garattini, Mineko Terao
Aldehyde oxidases are molybdoflavoenzymes with broad substrate specificity, oxidizing different types of aldehydes, and heterocyclic rings. The physiological function of aldehyde oxidases is largely unknown, although the enzymes play an important role in the metabolism of numerous compounds of medicinal and toxicological interest, as they oxidize a wide range of aldehydes and heterocyclic compounds. In this article, we review the significance of aldehyde oxidases for the design and development of new drugs and discuss associated problems. These include species-specific differences in the complement of isoenzymes synthesized and general difficulties in studying the enzymatic characteristics of purified or recombinant aldehyde oxidases. We highlight the potential offered by human aldehyde oxidase targeting for the development of new pharmacological agents, limiting our attention to the realms of antiobesity and anti-cancer drugs. The last point is discussed in the context of the design of novel anticancer drugs, selectively activated or inactivated by this enzyme, with the final aim of achieving organ and/or tumor selectivity.
Aldehyde toxicity and metabolism: the role of aldehyde dehydrogenases in detoxification, drug resistance and carcinogenesis
Published in Drug Metabolism Reviews, 2019
Amaj Ahmed Laskar, Hina Younus
Aldehydes are carbonyl compounds found ubiquitously in the environment, derived from both natural and anthropogenic sources. As the aldehydes are reactive species, therefore, they are generally toxic to the body. To reduce the toxicity and pathogenesis related to aldehydes, the human body contains several aldehyde metabolizing enzyme systems including aldehyde oxidases, cytochrome P450 enzymes, aldo-ketoreductases, alcohol dehydrogenases, short-chain dehydrogenases/reductases and aldehyde dehydrogenases (ALDHs). These enzyme systems maintain a low level of aldehydes in the body by catalytically converting them into less-harmful and easily excreted products. The human ALDH (hALDH) superfamily consists of 20 functional ALDH genes identified so far at distinct chromosomal locations, expressing 20 ALDH proteins, which belong to 11 different ALDH families. They are involved in the NAD(P)+-dependent oxidation of a wide range of exogenous and endogenous aldehydes to their corresponding carboxylic acids. The hALDHs are present in all sub-cellular locations and have a wide tissue distribution. This review gives an account of aldehydes; their source, toxicity and metabolism, different aldehyde metabolizing enzymes with special emphasis on ALDHs including their biochemical, physiological and pathophysiological roles in the body.
Role of Human Aldehyde Dehydrogenases in Endobiotic and Xenobiotic Metabolism
Published in Drug Metabolism Reviews, 2004
Vasilis Vasiliou, Aglaia Pappa, Tia Estey
The human genome contains at least 17 genes that are members of the aldehyde dehydrogenase (ALDH) superfamily. These genes encode NAD(P)+‐dependent enzymes that oxidize a wide range of aldehydes to their corresponding carboxylic acids. Aldehydes are highly reactive molecules that are intermediates or products involved in a broad spectrum of physiologic, biologic, and pharmacologic processes. Aldehydes are generated during retinoic acid biosynthesis and the metabolism of amino acids, lipids, carbohydrates, and drugs. Mutations in several ALDH genes are the molecular basis of inborn errors of metabolism and contribute to environmentally induced diseases.
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