Alcohols and Aldehydes
Frank A. Barile in Barile’s Clinical Toxicology, 2019
Alcohols and aldehydes are carbon compounds containing hydroxyl (H–R–OH) or carbonyl (H–R=O) groups. The chemicals affect biological processes directly or indirectly. Direct action of these compounds involves interaction of the parent molecules with the substrates of biological pathways. Indirect action interferes with metabolic products of the parent chemical. Ethanol, methanol, and isopropanol are important alcohols primarily because of their commercial availability, importance in a variety of essential chemical reactions, and involvement in intermediate chemical and biological pathways. Among the aldehydes, formaldehyde is ubiquitously distributed in the environment. Human exposure to this chemical has received considerable attention due to its human carcinogenic potential and developmental toxicity in laboratory animals.
Drug Design, Synthesis, and Development
Nathan Keighley in Miraculous Medicines and the Chemistry of Drug Design, 2020
When it comes to building a drug molecule, carbonyl chemistry offers a rich variety of reactions that can be used to create new functional groups, or make new carbon-carbon bonds, which are so important for combining different molecular fragments together that comprise the final target compound. Ketones and aldehydes are versatile functional groups and will undergo a diversity of reactions. The electronegative oxygen polarises the C=O bond, making the C susceptible to nucleophiles and the αH easily deprotonated with a base. Predominantly, ketones and aldehydes will undergo nucleophilic addition reactions; this includes reduction with hydrides to an alcohol and addition of nucleophiles to the carbonyl carbon. A range of nucleophiles can be used, including alcohols, amines, and cyanide, which are particularly useful in synthesis to introduce new functional groups, and Grignard’s reagent to make a new C–C bond. All of these basic organic reactions of carbonyls are invaluable for building a target compound.
Xenobiotic Biotransformation
Robert G. Meeks, Steadman D. Harrison, Richard J. Bull in Hepatotoxicology, 2020
Aldehyde reductase (EC 1.1.1.2.) catalyzes the reduction of carbonyl compounds. The enzyme is predominately cytosolic, with highest activity in kidney and significant activities in liver and brain. Carbonyl-containing substrates include aromatic aldehydes and ketones, aliphatic ketones, methyl, and unsaturated ketones. The metabolic functions of these enzymes are unknown, as are the physiological roles of aldehydes generated during intermediary metabolism. Since many aldehydes, particularly aldehyde derivatives of neurotransmitters, appear to be physiologically active, these enzymes may function to regulate endogenous aldehyde activity. At least three izoenzymes have been characterized. These include aldehyde reductase (the same isozyme as glucuronate reductase, mevaldate reductase, lactaldehyde reductase, and daunorubicin reductase), aldose reductase, and glycerol dehydrogenase.
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 a large class of organic compounds having a carbonyl carbon atom substituted with at least one hydrogen atom along with additional functional moieties. Aldehyde family is generally represented by R-CHO, where R is any functional moiety/carbon-containing substituent. Based on the nature of R group, aldehydes are divided into different subclasses. Broadly, they are classified into aliphatic and aromatic aldehydes which can be either saturated or unsaturated (Feron et al. 1991; Koren and Bisesi 2003). The different subclasses of aldehydes are (i) short chain aldehydes such as formaldehyde, acetaldehyde; (ii) long chain aldehydes such as hexanal, nonanal; (iii) aromatic aldehydes such as cinnamaldehyde, benzaldehyde; (iv) α,β-unsaturated aldehydes such as citral, acrolein; and (v) α-oxoaldehydes such as glyoxal, glycolaldehyde (O’Brien et al. 2005; LoPachin and Gavin 2014).
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 is the simplest aldehyde and exists as a colorless gas with a strong odor at room temperature. It was first synthesized in 1855 and is used for a variety of roles. This includes in embalming, the manufacture of particle-board, plywood, and other wooden furniture products and as a preservative in products such as cosmetics and medicinal creams [8]. When used as a preservative it is used as an aqueous solution of 37%-50% formaldehyde called formalin [9]. Formaldehyde is used as a preservative due to its genotoxicity to bacteria and fungi. It is capable of binding to DNA and proteins to cause DNA-DNA cross-links, DNA-protein cross-links, irreversible formaldehyde adducts as well as other forms of DNA and protein damage [10,11]. It is effective against bacteria at very low concentrations with the MIC of formaldehyde against S. aureus being only 156 mg/L or 0.02% [12]. Formaldehyde has also been used to treat bacterial infections in the form of the antibiotic methenamine. Methenamine is an antibiotic that was used to treat urinary tract infections but has since become a ‘forgotten drug’. It exerts its antibacterial activity by releasing formaldehyde in acidic environments and is capable of bactericidal activity at concentrations greater than 25 µg/ml [13].
Fatty acids, esters, and biogenic oil disinfectants: novel agents against bacteria
Published in Baylor University Medical Center Proceedings, 2023
Aruna Lamba, Jonathan Kopel, David Westenberg, Shubhender Kapila
Short-chain aldehydes are natural flavor and fragrance constituents that act as antimicrobial agents, delaying or preventing onset of decay.23,24 2-hexenal is noted to possess broad-spectrum antimicrobial activity. Although the precise mode of action of alkenals is not yet known, they likely permeate through passive diffusion across the plasma membrane. Once inside the cells, the aldehyde moiety readily reacts with biologically important nucleophilic groups like nucleic acid bases of a DNA strand, thiols, amides, and carboxyls.25 It has been shown that antibacterial activity against Salmonella choleraesuis increases with the addition of the CH2 group up to (2E)-dodecenal. The change in activity is most likely related to a balance between the hydrophilicity of the unsaturated aldehyde subunit and the hydrophobicity of the alkyl portion of the molecule, similar to their action against Saccharomyces cerevisiae.26 Gueldner et al demonstrated that the volatiles (2E)-hexenal, 2,4-hexadienal, 1-hexanol, furfural, β-ionone, 1-nonanol, and some synthetic compounds inhibit the growth of Aspergillus flavus. The antibacterial activity of these compounds was highest for the aldehydes followed by the ketones and then the alcohols.27 Cocciaoni et al reported that compounds such as esters, aldehydes, terpenes, alcohols, and hydrocarbons are more effective antimicrobial agents when used in the vapor phase than in the solution phase.28
Related Knowledge Centers
- Acetaldehyde
- Functional Group
- Organic Chemistry
- Organic Compound
- Formaldehyde
- Side Chain
- Orbital Hybridisation
- Chemical Polarity
- 1,3,5-Trioxane
- Vinyl Alcohol