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Quantification of Tissue Doses of Carcinogenic Aromatic Amines
Published in Frederick C. Kopfler, Gunther F. Craun, Environmental Epidemiology, 2019
Paul L. Skipper, Matthew S. Bryant, Steven R. Tannenbaum
Some of the early steps in the hepatic processing of aromatic amines are illustrated in Figure 1. One of the first important reactions which can occur is conjugation of the amines to form more water-soluble derivatives such as sulfamic acids or glucuronides which are excreted in urine or bile. C-hydroxylation to form phenols and conjugation of the phenols contribute in a major way to overall detoxification and removal. Acetylation, however, continues the process in the direction of toxicity. It is probably a major determinant of organ specificity in that non-acetylated metabolites are implicated in urinary bladder carcinogenesis, whereas acetylated metabolites appear to target other organs, such as the liver. Both amines and acetamides share a common toxification reaction, N-hydroxylation. In some cases the resultant hydroxylamine or hydroxamic acid reacts directly with cellular targets, and in other cases, esterification or acyl transfer is necessary before reaction occurs. In any event, the production of one of these two intermediates is probably obligatory for the ultimate formation of any macromolecular adducts, whether they are formed with DNA or with protein. For a comprehensive review of the metabolism of aromatic amines, see, for example, Garner et al. [9].
Natural Products Affecting Biofilm Formation
Published in Bakrudeen Ali Ahmed Abdul, Microbial Biofilms, 2020
Jacqueline Cosmo Andrade Pinheiro, Maria Audilene Freitas, Bárbara de Azevedo Ramos, Luciene Ferreira de Lima, Henrique Douglas Melo Coutinho
Several studies have shown positive results in biofilm reduction using established models, however, compounds which do not reduce biofilm formation exist, such as the following substances studied by Helaly et al. (2017). The akanthol, akanthozine, and three amide derivatives including one hydroxamic acid derivative were taken from a spider-associated fungus, Akanthomyces novoguineensis, and tested for various biological activities, including antibiofilm activity. However, these compounds did not present any preventive effects against biofilm formation in Staphylococcus aureus DSM1104 (ATCC25923) and Pseudomonas aeruginosa PA14, nor did they show significant results in antimicrobial, cytotoxic, or nematicide activities.
N-Heterocyclic Carbene Catalysis
Published in Andrew M. Harned, Nonnitrogenous Organocatalysis, 2017
Xinqiang Fang, Yonggui Robin Chi
By elaborate design of the reaction process, Bode and coworkers developed an elegant relay catalysis approach for the catalytically kinetic resolution of cyclic secondary amines.33 Chiral hydroxamic acid 120 was the key point of the reaction, but the work also took advantage of the reactivity of acyl azolium 122, which was produced from the reaction of NHC 115′ with α′-hydroxyenone 118. The catalytically generated azylazolium 122 was inert to amine 119 but active to hydroxamic acid 120, and the corresponding ester derivative 123 was the active acylating agent. The s factor ranged from 8 to 74 in the kinetic resolution of cyclic secondary amines (Figure 7.29).
Nitrosubstituted hydroxamate ligands in new triphenyltin(IV) complexes as prospective antimicrobial agents
Published in Journal of Coordination Chemistry, 2019
Hydroxamic acids RC(O)NHOH, an important class of organic bioligands and bioactive compounds, have been used as supporting ligands in organometallic chemistry and biology. They have excellent chelating properties on account of tautomerism, displaying hydroxamato/imato binding modes and potential as therapeutic agents [1–4]. The medicinal chemistry and pharmacology of hydroxamic acid derivatives and their ability as potent and selective inhibitors of a range of metalloenzymes continue to arouse interest [5]. The physiological role of hydroxamic acids as siderophores for the development of bio conjugates utilized as carriers to selectively deliver antimicrobial prodrug to the site of action is well-documented [6]. Many reports on diverse applications of hydroxamic acids reveal that they impact coordination chemistry, chemical biology, and medical science [7–11].
Collector Chemistry for Bastnaesite Flotation – Recent Developments
Published in Mineral Processing and Extractive Metallurgy Review, 2019
Weiping Liu, Xuming Wang, Jan D. Miller
Hydroxamic acid, with the formula of RC(O)N(OH)R′, is widely used as a metal chelating reagent. The R and R′ are organic radicals. The pKa of hydroxamic acid is reported to be in the range of 7.05 to 11.33, according to its chemical structure (Fuerstenau and Pradip 2013). Since hydroxamate was first used as a collector for metal oxide flotation (Peterson et al. 1965), the use of alkyl hydroxamate as a collector in numerous flotation systems has been studied extensively, including its use for bastnaesite flotation.
Synthesis, characterization and evaluation of antimicrobial potential of zinc(II) complexes of nitro-substituted hydroxamic acid chelators
Published in Journal of Coordination Chemistry, 2022
Shubham Sharma, Neeraj Sharma, Meena Kumari, Mridula Thakur
Hydroxamic acids show wide spectrum of biological activities and generally have low toxicities [9, 10]. Hydroxamic acids containing the –C(O)NHOH functionality constitute an important family of organic bio-ligands. These have been the subject of enormous research interest because of their broad spectrum of biological activities in medicine as analgesic, anti-inflammatories, collagenase inhibitors, anti-infective, antibiotics, anticancer agents, etc. Cinnamohydroxamic acid and its derivatives have been used for the treatment of symptoms of asthma and other obstructive airway diseases which inhibit 5-lipoxygenase. Hydroxamic acid analogues have been reported to inhibit DNA synthesis by inactivating the enzyme ribonucleotide reductase (RNR). Naturally occurring hydroxamic acid 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA) is a powerful antibiotic present in maize [11]. The antiradical and antioxidant properties of hydroxamic acids have been reported [12]. Hydroxamic acids play important roles in many chemical, biochemical, pharmaceutical, analytical and industrial fields [13, 14]. The biological activities of hydroxamic acids are due to their diverse complexation behavior towards transition metal ions [15], which has been studied both in solution as well as in solid state. Hydroxamic acids usually act as bidentate (O,O’)-chelates through the carbonyl and hydroxamic oxygen atoms forming five-membered rings in which the ligand is either singly deprotonated (hydroxamato) or doubly deprotonated [R(O-)C = NO-] (hydroximato) [16–18]. The experimental and theoretical studies have established that hydroxamic form is the dominant one in free acids or metal hydroxamates. Besides the O,O’-bonding mode, in a few cases N,O- and N,N’-coordination involving the hydroxamate nitrogen and α-amino nitrogen (α-aminohydroxamic acids) has been described [19–21]. The affinity between hydroxamic acids and transition metal ions is quite apparent in the X-ray crystal structures of Ni(II)-containing urease [22] or Zn(II)-containing metalloproteins such as carbonic anhydrase [23], or matrix metalloproteases (MMPs), where hydroxamic acids are bound to the Ni(II) or Zn(II) active sites [24–26]. The intensely colored solutions of metal hydroxamates have been widely used in analytical applications. Hydroxamic acids and their derivatives can be used as pharmacological agents and with electron-withdrawing substituents like –NO2, –Cl, etc. (–NO2 in present work) upon complexation with metals show enhanced biological activity [27]. Metal hydroxamates also find use as models for understanding the role of the hydroxamate group in biological systems [28]. With the backdrop of our research interest on the synthesis of vanadium(IV) hydroxamates [29–32] and organotin(IV) hydroxamates [33–35] and in view of the biological importance of zinc complexes, the present work aims at the synthesis of new zinc(II) hydroxamates and evaluation of their antimicrobial potential in search of better antimicrobial candidates.