Journal articles: 'Quinones'

1

Weiss, Sophie A., and Lars J. C. Jeuken. "Electrodes modified with lipid membranes to study quinone oxidoreductases." Biochemical Society Transactions 37, no. 4 (July 22, 2009): 707–12. http://dx.doi.org/10.1042/bst0370707.

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Quinone oxidoreductases are a class of membrane enzymes that catalyse the oxidation or reduction of membrane-bound quinols/quinones. The conversion of quinone/quinol by these enzymes is difficult to study because of the hydrophobic nature of the enzymes and their substrates. We describe some biochemical properties of quinones and quinone oxidoreductases and then look in more detail at two model membranes that can be used to study quinone oxidoreductases in a native-like membrane environment with their native lipophilic quinone substrates. The results obtained with these model membranes are compared with classical enzyme assays that use water-soluble quinone analogues.

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2

Gutiérrez, Isela, Sonia G. Bertolotti, M. A. Biasutti, Arnaldo T. Soltermann, and Norman A. García. "Quinones and hydroxyquinones as generators and quenchers of singlet molecular oxygen." Canadian Journal of Chemistry 75, no. 4 (April 1, 1997): 423–28. http://dx.doi.org/10.1139/v97-048.

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The role of quinones and hydroxyquinones as sensitizers and as quenchers in Type II photooxygenations has been examined. The second aspect is discussed here, through a systematic study, for the first time in the open literature. Quinonic compounds are excellent generators of O2(1Δg) in aprotic solvents (excluding those quinones possessing substituents in positions adjacent to the carbonyl groups, in the case of anthraquinone derivatives). Benzoquinones, anthraquinones, and hydroxy derivatives are good O2(1Δg) quenchers upon dye-sensitized photoirradiation. The excited oxygen species is deactivated with rate constants in the range 106–107 M−1 s−1 depending on the solvent employed. The quenching process deactivates O2(1Δg) without further destruction of the quinone. The main interaction with O2(1Δg) is driven by the quinone moiety, in spite of the presence of potentially active nuclear substituents. The quenching mechanism could involve a reversible charge transfer intermediate, with the quinonic compound acting as an electron donor. Keywords: photooxidation, quenching, quinones, rose bengal, singlet oxygen.

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3

Wengryniuk, Sarah E., and Xiao Xiao. "Recent Advances in the Selective Oxidative Dearomatization of Phenols to o-Quinones and o-Quinols with Hypervalent Iodine Reagents." Synlett 32, no. 08 (January 14, 2021): 752–62. http://dx.doi.org/10.1055/s-0037-1610760.

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Abstract ortho-Quinones are valuable molecular frameworks with diverse applications across biology, materials, organic synthesis, catalysis, and coordination chemistry. Despite their broad utility, their synthesis remains challenging, in particular via the direct oxidation of readily accessible phenols, due to the need to affect regioselective ortho oxidation coupled with the sensitivity of the resulting o-quinone products. The perspective looks at the emergence of I(V) hypervalent iodine reagents as an effective class of oxidants for regioselective o-quinone synthesis. The application of these reagents in regioselective phenol oxidation to both o-quinones and o-quinols will be discussed, including a recent report from our laboratory on the first method for the oxidation of electron-deficient phenols using a novel nitrogen-ligated I(V) reagent. Also included are select examples of total syntheses utilizing this methodology as well as recent advancements in chiral I(V) reagent design for asymmetric phenol dearomatization.1 Introduction2 I(V): Hypervalent Iodine Reagents3 I(V)-Mediated Dearomatization to o-Quinones4 Bisnitrogen-Ligated I(V) Reagents: ortho Dearomatization of Electron-Poor Phenols5 I(V)-Mediated Dearomatization to o-Quinols6 Conclusion and Outlook

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4

Becker, James Y. "Electrochemistry of Diquinonyl Amines with an Internal Proton Source." ECS Meeting Abstracts MA2024-01, no. 41 (August 9, 2024): 2340. http://dx.doi.org/10.1149/ma2024-01412340mtgabs.

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It is well established that quinones play an important role in various biological systems. Studying electrochemical properties of quinones affords fundamental knowledge of semi-quinone radicals formation in vivo and in vitro in different media. Following our previous work on electrochemical properties of various quinonyl amines [1], Scheme 1 below describes seven diquinonyl amines. Noteworthy that six of them (1-6) contain an internal proton donor (‘NH’) except for the seventh one (7), in which both quinone moieties are attached to ‘NMe’ group. Their redox potentials were measured by cyclic voltammetry in dichloromethane [2]. The results show a strong dependence of the nature of substituent on the first reduction potentials, and that protonation of diquinonyl amines is feasible by internal proton source even in a non-polar medium. References [1] S. Bittner, S. Gorohovsky, O. Paz-Tal (Levi), J.Y. Becker, Amino Acids, 2002, 22, 71-93 [2] G. Temtsin-Krayz, S. Bittner, A. Dhiman and J.Y. Becker, "Electrochemistry of Quinones with Respect to their Role in Biomedical Chemistry", Chem. Rec., 2021, 21. Figure 1

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Ito, Shosuke, Manickam Sugumaran, and Kazumasa Wakamatsu. "Chemical Reactivities of ortho-Quinones Produced in Living Organisms: Fate of Quinonoid Products Formed by Tyrosinase and Phenoloxidase Action on Phenols and Catechols." International Journal of Molecular Sciences 21, no. 17 (August 24, 2020): 6080. http://dx.doi.org/10.3390/ijms21176080.

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Tyrosinase catalyzes the oxidation of phenols and catechols (o-diphenols) to o-quinones. The reactivities of o-quinones thus generated are responsible for oxidative browning of plant products, sclerotization of insect cuticle, defense reaction in arthropods, tunichrome biochemistry in tunicates, production of mussel glue, and most importantly melanin biosynthesis in all organisms. These reactions also form a set of major reactions that are of nonenzymatic origin in nature. In this review, we summarized the chemical fates of o-quinones. Many of the reactions of o-quinones proceed extremely fast with a half-life of less than a second. As a result, the corresponding quinone production can only be detected through rapid scanning spectrophotometry. Michael-1,6-addition with thiols, intramolecular cyclization reaction with side chain amino groups, and the redox regeneration to original catechol represent some of the fast reactions exhibited by o-quinones, while, nucleophilic addition of carboxyl group, alcoholic group, and water are mostly slow reactions. A variety of catecholamines also exhibit side chain desaturation through tautomeric quinone methide formation. Therefore, quinone methide tautomers also play a pivotal role in the fate of numerous o-quinones. Armed with such wide and dangerous reactivity, o-quinones are capable of modifying the structure of important cellular components especially proteins and DNA and causing severe cytotoxicity and carcinogenic effects. The reactivities of different o-quinones involved in these processes along with special emphasis on mechanism of melanogenesis are discussed.

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6

Ellis, Jessie, Xueyan Fu, J. Philip Karl, Patrick Radcliffe, Jason Soares, Laurel Doherty, Christopher Hernandez, Joel Mason, Angela Oliverio, and Sarah Booth. "Investigation of Vitamin K Quinone Metabolism by Human Gut Bacteria." Current Developments in Nutrition 4, Supplement_2 (May 29, 2020): 392. http://dx.doi.org/10.1093/cdn/nzaa045_025.

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Abstract Objectives Vitamin K (VK) is a family of structurally-related quinones, phylloquinone (PK) and menaquinones (MKn, n = prenyl units in side chain), that share a common napthoquinone ring (menadione, MD). VK quinones function as an essential dietary nutrient for humans. MD is considered a pro-vitamin form of VK. Plants and bacteria that produce VK quinones (PK and MKn, respectively) use them as an electron carrier in energy production. Little is known about the interaction of dietary VK quinones with gut bacteria, which may be bi-directional. The objective of this study was to investigate the influence of VK quinones and MD on human gut bacteria composition and MKn production. Methods Stool from 5 healthy male donors was pooled and inoculated in bioreactors under conditions mimicking the colon (anaerobic, pH 6.8, 37°C) for 48 h. Bioreactors were treated with deuterium (2H)-labeled quinones (2H-PK, 2H-MK4, 2H-MK9 or 2H-MD); no quinones (cell controls); or 2H-quinone treatment with no stool (cell-free controls). Culture aliquots were collected at 0, 5, 10, 24, and 48 h, and separated into pellet and supernatant fractions. Experiments were conducted in triplicate. All fractions were analyzed for VK quinone content using LC-MS. DNA from 0 and 24 h pellet fractions was extracted and amplified for paired-end 16S sequencing on an Illumina MiSeq 2500. Differences in bacterial composition were assessed using PERMANOVA. Results Supplemented 2H-quinones accumulated in the pellet fraction over time. This was not observed in cell-free controls and was thus not a function of culture media solubility. Endogenous (unlabeled) production of MKn was unaffected by supplementation of 2H-quinones. Generated 2H-MKn (2H-MK4, 2H-MK9, 2H-MK10, and 2H-MK11) were only detected in 2H-MD supplemented vessels. Community-wide bacterial composition significantly differed between 0 h and 24 h (r2 = 0.85, P = 0.001), but not by quinone treatment. Conclusions PK and MKn, dietary viamin K quinones, were not transformed by gut microbes to MKn in vitro, whereas the pro-vitamin quinone MD was transformed to MKn of multiple side chain lengths. Although no quinone induced community-wide changes in bacteria composition, additional analyses are needed to assess species-specific growth promotion. Funding Sources USDA ARS and DOD Health Program.

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7

MacDonald, Michael J. "Stimulation of insulin release from pancreatic islets by quinones." Bioscience Reports 11, no. 3 (June 1, 1991): 165–70. http://dx.doi.org/10.1007/bf01182485.

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Coenzyme Q (CoQ0) and other quinones were shown to be potent insulin secretagogues in the isolated pancreatic islet. The order of potency was CoQ0≅benzoquinone≅hydroquinonemenadione. CoQ6 and CoQ10 (ubiquinone), duroquinone and durohydroquinone did not stimulate insulin release. CoQ0's insulinotropism was enhanced in calcium-free medium and CoQ0 appeared to stimulate only the second phase of insulin release. CoQ0 inhibited inositol mono-, bis- and trisphosphate formation. Inhibitors of mitochondrial respiration (rotenone, antimycin A, FCCP and cyanide) and the calcium channel blocker verapamil, did not inhibit CoQ0-induced insulin release. Dicumarol, an inhibitor of quinone reductase, did not inhibit CoQ0-induced insulin release, but it did inhibit glucose-induced insulin release suggesting that the enzyme and quinones play a role in glucose-induced insulin release. Quinones may stimulate insulin release by mimicking physiologically-occuring quinones, such as CoQ10, by acting on the plasma membrane or in the cytosol. Exogenous quinones may bypass the quinone reductase reaction, as well as many reactions important for exocytosis.

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8

Li, Zhi, and Xiao-Long Xu. "Deciphering the Redox Chain Mechanism in the Catalytic Alkylation of Quinones." Synlett 29, no. 14 (May 14, 2018): 1807–13. http://dx.doi.org/10.1055/s-0037-1610125.

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Alkylation of p-quinones with allylic and benzylic esters is achieved by using a strong Lewis acid as the catalyst. This transformation likely follows an unusual redox chain mechanism. In this mechanism, quinone undergoes a sequence of reactions: it is reduced to hydroquinone (HQ), functionalized in a Lewis acid-catalyzed Friedel–Crafts alkylation, and then oxidized back to quinone. The last step is concurrent with the first step of a second quinone molecule, which is reduced to new HQ and functionalized, and thus propagates the redox chain reaction. The autoinitiation mechanism of the redox chain is not well understood, but additive HQ or Hantzsch ester can serve as effective initiators. The likelihood of this mechanism was elaborated by kinetic studies and various control experiments.1 Introduction2 Discovery of Catalytic Alkylation Reactions of Quinones3 Proposed Redox Chain Reaction Mechanism and Experimental Evidence4 Substrate Scope5 Conclusion

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9

Begleiter, Asher. "The contribution of alkylation to the activity of quinone antitumor agents." Canadian Journal of Physiology and Pharmacology 64, no. 5 (May 1, 1986): 581–85. http://dx.doi.org/10.1139/y86-096.

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Studies have shown that the quinone group can produce tumor cell kill by a mechanism involving active oxygen species. This cytotoxic activity can be correlated with the induction of DNA double strand breaks and is enhanced by the ability of the quinone compound to bind to DNA by alkylation. The cytotoxic activity and the production of DNA damage by model quinone antitumor agents were compared in L5178Y cells, sensitive and resistant to alkylating agents, to assess the contribution of alkylation to the activity of these agents. The resistant L5178Y/HN2 cells were found to be two fold and six fold more resistant to the alkylating quinones, benzoquinone mustard and benzoquinone dimustard, respectively, than parent L5178Y cells. In contrast, the L5178 Y/HN2 cells showed no resistance to the nonalkylating quinones, hydrolyzed benzoquinone mustard and bis(dimethylamino)benzoquinone. The alkylating quinones produced approximately two fold less cross-linking in L5178Y/HN2 cells compared with L5178Y sensitive cells. DNA double strand break formation by hydrolyzed benzoquinone mustard and bis(dimethylamino)benzoquinone was not significantly different in sensitive and resistant cells. However, the induction of double strand breaks by the alkylating quinones benzoquinone mustard and benzoquinone dimustard was reduced by 5-fold and 15-fold, respectively, in L5178Y/HN2 cells. These results show that the alkylating activity of the alkylating quinones cannot directly explain all of the enhanced cytotoxic activity of these agents. Furthermore, they provide strong evidence that the enhanced formation of DNA double strand breaks by alkylating quinone agents is directly related to the ability of these agents to bind to DNA. This increased formation of strand breaks may account for the enhanced cytotoxic activity of the alkylating quinones.

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10

Juliasih, Ni Luh Gede Ratna, Lee Chang Yuan, Yuki Sago, Yoichi Atsuta, and Hiroyuki Daimon. "Supercritical Fluid Extraction of Quinones from Compost for Microbial Community Analysis." Journal of Chemistry 2015 (2015): 1–7. http://dx.doi.org/10.1155/2015/717616.

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Supercritical fluid extraction (SFE) was used to extract quinones from compost to monitor the microbial community dynamics during composting. The 0.3 g of dried compost was extracted using 3 mL min−1of carbon dioxide (90%) and methanol (10%) at 45°C and 25 MPa for a 30 min extraction time. The extracted quinones were analysed using ultra performance liquid chromatography (UPLC) with 0.3 mL min−1of methanol mobile phase for a 50 min chromatographic run time. A comparable detected amount of quinones was obtained using the developed method and an organic solvent extraction method, being 36.06 μmol kg−1and 34.54 μmol kg−1, respectively. Significantly low value of dissimilarity index (D) between the two methods (0.05) indicated that the quinone profile obtained by both methods was considered identical. The developed method was then applied to determine the maturity of the compost by monitoring the change of quinone during composting. The UQ-9 and MK-7 were predominant quinones in the initial stage of composting. The diversity of quinone became more complex during the cooling and maturation stages. This study showed that SFE had successfully extracted quinones from a complex matrix with simplification and rapidity of the analysis that is beneficial for routine analysis.

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11

Miseviciene, Lina, Zilvinas Anusevicius, Jonas Sarlauskas, Richard J. Harris, Nigel S. Scrutton, and Narimantas Cenas. "Two-electron reduction of quinones by Enterobacter cloacae PB2 pentaerythritol tetranitrate reductase: quantitative structure-activity relationships." Acta Biochimica Polonica 54, no. 2 (June 4, 2007): 379–85. http://dx.doi.org/10.18388/abp.2007_3260.

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In order to clarify the poorly understood mechanisms of two-electron reduction of quinones by flavoenzymes, we examined the quinone reductase reactions of a member of a structurally distinct old yellow enzyme family, Enterobacter cloacae PB2 pentaerythritol tetranitrate reductase (PETNR). PETNR catalyzes two-electron reduction of quinones according to a 'ping-pong' scheme. A multiparameter analysis shows that the reactivity of quinones increases with an increase in their single-electron reduction potential and pK(a) of their semiquinones (a three-step (e(-),H(+),e(-)) hydride transfer scheme), or with an increase in their hydride-transfer potential (E(7)(H(-))) (a single-step (H(-)) hydride transfer scheme), and decreases with a decrease in their van der Waals volume. However, the pH-dependence of PETNR reactivity is more consistent with a single-step hydride transfer. A comparison of X-ray data of PETNR, mammalian NAD(P)H : quinone oxidoreductase (NQO1), and Enterobacter cloacae nitroreductase, which reduce quinones in a two-electron way, and their reactivity revealed that PETNR is much less reactive, and much less sensitive to the quinone substrate steric effects than NQO1. This may be attributed to the lack of pi-pi stacking between quinone and the displaced aromatic amino acid in the active center, e.g., with Phe-178' in NQO1.

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12

Vienozinskis, J., A. Butkus, N. Cenas, and J. Kulys. "The mechanism of the quinone reductase reaction of pig heart lipoamide dehydrogenase." Biochemical Journal 269, no. 1 (July 1, 1990): 101–5. http://dx.doi.org/10.1042/bj2690101.

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The relationship between the NADH:lipoamide reductase and NADH:quinone reductase reactions of pig heart lipoamide dehydrogenase (EC 1.6.4.3) was investigated. At pH 7.0 the catalytic constant of the quinone reductase reaction (kcat.) is 70 s-1 and the rate constant of the active-centre reduction by NADH (kcat./Km) is 9.2 x 10(5) M-1.s-1. These constants are almost an order lower than those for the lipoamide reductase reaction. The maximal quinone reductase activity is observed at pH 6.0-5.5. The use of [4(S)-2H]NADH as substrate decreases kcat./Km for the lipoamide reductase reaction and both kcat. and kcat./Km for the quinone reductase reaction. The kcat./Km values for quinones in this case are decreased 1.85-3.0-fold. NAD+ is a more effective inhibitor in the quinone reductase reaction than in the lipoamide reductase reaction. The pattern of inhibition reflects the shift of the reaction equilibrium. Various forms of the four-electron-reduced enzyme are believed to reduce quinones. Simple and ‘hybrid ping-pong’ mechanisms of this reaction are discussed. The logarithms of kcat./Km for quinones are hyperbolically dependent on their single-electron reduction potentials (E1(7]. A three-step mechanism for a mixed one-electron and two-electron reduction of quinones by lipoamide dehydrogenase is proposed.

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13

Norkov, Sergey V., Anton V. Cherkasov, Andrey S. Shavyrin, Maxim V. Arsenyev, Viacheslav A. Kuropatov, and Vladimir K. Cherkasov. "Annulation of a 1,3-dithiole ring to a sterically hindered o-quinone core. Novel ditopic redox-active ligands." Beilstein Journal of Organic Chemistry 17 (January 27, 2021): 273–82. http://dx.doi.org/10.3762/bjoc.17.26.

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The fused 1,3-dithiole spacer seems to be very suitable for the functionalization of sterically hindered o-quinones with additional groups capable of coordination of metal ions and/or possessing a redox activity. An effective method for the synthesis of sterically hindered o-quinones containing 1,3-diketonate, dinitrile and p-quinone-methide functional groups at the periphery of the ligand has been developed. The novel compounds have rigid and conjugated structures and exhibit properties typical of o-quinones. A study of their monoreduced semiquinone derivatives reveal that the spin density is delocalized across the whole molecule, including peripheral fragments. The first stable o-quinone derivative bearing an annulated thiete heterocycle has been isolated and characterized.

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14

Cores, Ángel, Noelia Carmona-Zafra, José Clerigué, Mercedes Villacampa, and J. Carlos Menéndez. "Quinones as Neuroprotective Agents." Antioxidants 12, no. 7 (July 20, 2023): 1464. http://dx.doi.org/10.3390/antiox12071464.

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Quinones can in principle be viewed as a double-edged sword in the treatment of neurodegenerative diseases, since they are often cytoprotective but can also be cytotoxic due to covalent and redox modification of biomolecules. Nevertheless, low doses of moderately electrophilic quinones are generally cytoprotective, mainly due to their ability to activate the Keap1/Nrf2 pathway and thus induce the expression of detoxifying enzymes. Some natural quinones have relevant roles in important physiological processes. One of them is coenzyme Q10, which takes part in the oxidative phosphorylation processes involved in cell energy production, as a proton and electron carrier in the mitochondrial respiratory chain, and shows neuroprotective effects relevant to Alzheimer’s and Parkinson’s diseases. Additional neuroprotective quinones that can be regarded as coenzyme Q10 analogues are idobenone, mitoquinone and plastoquinone. Other endogenous quinones with neuroprotective activities include tocopherol-derived quinones, most notably vatiquinone, and vitamin K. A final group of non-endogenous quinones with neuroprotective activity is discussed, comprising embelin, APX-3330, cannabinoid-derived quinones, asterriquinones and other indolylquinones, pyrroloquinolinequinone and its analogues, geldanamycin and its analogues, rifampicin quinone, memoquin and a number of hybrid structures combining quinones with amino acids, cholinesterase inhibitors and non-steroidal anti-inflammatory drugs.

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15

Laatsch, Hartmut. "Methylierung 3,3′-dihydroxylierter 2,2′-Binaphthyl-1,4;1′,4′-dichinone / Methylation of 3,3′-Dihydroxylated 2,2′-Binaphtho-1,4;1′,4′-quinones." Zeitschrift für Naturforschung B 45, no. 3 (March 1, 1990): 393–400. http://dx.doi.org/10.1515/znb-1990-0316.

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Monomeric hydroxy-p-quinones (1) are in equilibrium with the corresponding o-quinones (2) and on methylation, a mixture of both isomeric ethers is obtained. In contrast, dimeric hydroxynaphthoquinones with the 3 a-skeleton in treatment with diazomethane are yielding only p-quinone ethers of type 3b.

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Flynn, Noah R., Michael D. Ward, Mary A. Schleiff, Corentine M. C. Laurin, Rohit Farmer, Stuart J. Conway, Gunnar Boysen, S. Joshua Swamidass, and Grover P. Miller. "Bioactivation of Isoxazole-Containing Bromodomain and Extra-Terminal Domain (BET) Inhibitors." Metabolites 11, no. 6 (June 15, 2021): 390. http://dx.doi.org/10.3390/metabo11060390.

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The 3,5-dimethylisoxazole motif has become a useful and popular acetyl-lysine mimic employed in isoxazole-containing bromodomain and extra-terminal (BET) inhibitors but may introduce the potential for bioactivations into toxic reactive metabolites. As a test, we coupled deep neural models for quinone formation, metabolite structures, and biomolecule reactivity to predict bioactivation pathways for 32 BET inhibitors and validate the bioactivation of select inhibitors experimentally. Based on model predictions, inhibitors were more likely to undergo bioactivation than reported non-bioactivated molecules containing isoxazoles. The model outputs varied with substituents indicating the ability to scale their impact on bioactivation. We selected OXFBD02, OXFBD04, and I-BET151 for more in-depth analysis. OXFBD’s bioactivations were evenly split between traditional quinones and novel extended quinone-methides involving the isoxazole yet strongly favored the latter quinones. Subsequent experimental studies confirmed the formation of both types of quinones for OXFBD molecules, yet traditional quinones were the dominant reactive metabolites. Modeled I-BET151 bioactivations led to extended quinone-methides, which were not verified experimentally. The differences in observed and predicted bioactivations reflected the need to improve overall bioactivation scaling. Nevertheless, our coupled modeling approach predicted BET inhibitor bioactivations including novel extended quinone methides, and we experimentally verified those pathways highlighting potential concerns for toxicity in the development of these new drug leads.

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Jensen,, Kenneth A., Zachary C. Ryan, Amber Vanden Wymelenberg, Daniel Cullen, and Kenneth E. Hammel. "An NADH:Quinone Oxidoreductase Active during Biodegradation by the Brown-Rot Basidiomycete Gloeophyllum trabeum." Applied and Environmental Microbiology 68, no. 6 (June 2002): 2699–703. http://dx.doi.org/10.1128/aem.68.6.2699-2703.2002.

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ABSTRACT The brown-rot basidiomycete Gloeophyllum trabeum uses a quinone redox cycle to generate extracellular Fenton reagent, a key component of the biodegradative system expressed by this highly destructive wood decay fungus. The hitherto uncharacterized quinone reductase that drives this cycle is a potential target for inhibitors of wood decay. We have identified the major quinone reductase expressed by G. trabeum under conditions that elicit high levels of quinone redox cycling. The enzyme comprises two identical 22-kDa subunits, each with one molecule of flavin mononucleotide. It is specific for NADH as the reductant and uses the quinones produced by G. trabeum (2,5-dimethoxy-1,4-benzoquinone and 4,5-dimethoxy-1,2-benzoquinone) as electron acceptors. The affinity of the reductase for these quinones is so high that precise kinetic parameters were not obtainable, but it is clear that k cat/Km for the quinones is greater than 108 M−1 s−1. The reductase is encoded by a gene with substantial similarity to NAD(P)H:quinone reductase genes from other fungi. The G. trabeum quinone reductase may function in quinone detoxification, a role often proposed for these enzymes, but we hypothesize that the fungus has recruited it to drive extracellular oxyradical production.

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Breker, Johannes, Reinhard Schmutzler, Bernd Dorbath, and Markus Wieber. "Reaktionen von unsymmetrischen λ5P – λ3P-Diphosphorverbindungen und von Diphosphinen (λ3P – λ3P) mit o-Chinonen / Reactions of Unsymmetrical λ5Ρ – λ3Ρ Diphosphorus Compounds and of Diphosphines (λ3P – λ3P) with o-Quinones." Zeitschrift für Naturforschung B 45, no. 8 (August 1, 1990): 1177–86. http://dx.doi.org/10.1515/znb-1990-0812.

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The reaction of λ5Ρ – λ3Ρ diphosphorus compounds with o-quinones, e.g. tetrachloro-o-benzoquinone or 2,5-di-tert-butyl-o-benzoquinone, led not only to oxidative addition of the o-quinone to λ3Ρ but also to insertion of a further molecule of o-quinone into the P–P bond (i.e. λ5Ρ – λ3Ρ diphosphorus compound and o-quinone reacted in a molar ratio 1:2). In the course of these oxidative addition and insertion reactions the o-quinones were converted into the corresponding hydroquinones (i.e. catechols). The products of these reactions were characterized by NMR and mass spectrometric methods, and by elemental analysis. The hydrolysis of the 1:2 addition products proceeded with cleavage of a P–O–C (hydroquinone) bond and formation of mononuclear products, involving λ4Ρ and λ5Ρ, respectively. A mechanism of this hydrolysis is proposed and has been elucidated by independent synthesis of some products. Diphosphines, i.e. symmetrical λ3Ρ – λ3Ρ diphosphorus compounds, were found to react with o-quinones in the same fashion in a molar ratio 1:3, i.e. with oxidative addition of the o-quinone to both λ3P atoms and insertion of tetrachloro-o-catechol into the P–P bond.

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Lesanavičius, Mindaugas, Alessandro Aliverti, Jonas Šarlauskas, and Narimantas Čėnas. "Reactions of Plasmodium falciparum Ferredoxin:NADP+ Oxidoreductase with Redox Cycling Xenobiotics: A Mechanistic Study." International Journal of Molecular Sciences 21, no. 9 (May 2, 2020): 3234. http://dx.doi.org/10.3390/ijms21093234.

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Ferredoxin:NADP+ oxidoreductase from Plasmodium falciparum (PfFNR) catalyzes the NADPH-dependent reduction of ferredoxin (PfFd), which provides redox equivalents for the biosynthesis of isoprenoids and fatty acids in the apicoplast. Like other flavin-dependent electrontransferases, PfFNR is a potential source of free radicals of quinones and other redox cycling compounds. We report here a kinetic study of the reduction of quinones, nitroaromatic compounds and aromatic N-oxides by PfFNR. We show that all these groups of compounds are reduced in a single-electron pathway, their reactivity increasing with the increase in their single-electron reduction midpoint potential (E17). The reactivity of nitroaromatics is lower than that of quinones and aromatic N-oxides, which is in line with the differences in their electron self-exchange rate constants. Quinone reduction proceeds via a ping-pong mechanism. During the reoxidation of reduced FAD by quinones, the oxidation of FADH. to FAD is the possible rate-limiting step. The calculated electron transfer distances in the reaction of PfFNR with various electron acceptors are similar to those of Anabaena FNR, thus demonstrating their similar “intrinsic” reactivity. Ferredoxin stimulated quinone- and nitro-reductase reactions of PfFNR, evidently providing an additional reduction pathway via reduced PfFd. Based on the available data, PfFNR and possibly PfFd may play a central role in the reductive activation of quinones, nitroaromatics and aromatic N-oxides in P. falciparum, contributing to their antiplasmodial action.

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Khetan, Abhishek. "High-Throughput Virtual Screening of Quinones for Aqueous Redox Flow Batteries: Status and Perspectives." Batteries 9, no. 1 (December 28, 2022): 24. http://dx.doi.org/10.3390/batteries9010024.

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Quinones are one of the most promising and widely investigated classes of redox active materials for organic aqueous redox flow batteries. However, quinone-based flow batteries still lack the necessary performance in terms of metrics, such as specific capacity, power density, and long-term stability, to achieve mass market adoption. These performance metrics are directly related to the physicochemical properties of the quinone molecules, including their equilibrium redox potential, aqueous solubility, and chemical stability. Given the enormous chemical and configurational space of possible quinones and the high tunability of their properties, there has been a recent surge in the use of high-throughput virtual screening (HTVS) for the rational design and discovery of new high-performing molecules. In this review article, HTVS efforts for the computational design and discovery of quinones are reviewed with a special focus on the enumerated space of core quinone motif, the methods and approximations used for the estimation of performance descriptors, and the emergent structure-property relationships. The knowledge and methodological gaps in conventional HTVS efforts are discussed, and strategies for improvement are suggested.

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Baxter, Ryan, Akil Hamsath, and Jordan Galloway. "Quinone C–H Alkylations via Oxidative Radical Processes." Synthesis 50, no. 15 (June 6, 2018): 2915–23. http://dx.doi.org/10.1055/s-0037-1610005.

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A brief survey of radical additions to quinones is reported. Carboxylic acids, aldehydes, and unprotected amino acids are compared as alkyl radical precursors for the mono- or bis- C–H alkylation of several quinones. Two methods for radical initiation are discussed comparing inorganic persulfates and Selectfluor as stoichiometric oxidants. Kinetic analysis reveals dramatic differences in the rate of radical initiation depending on the identity of the radical precursor and oxidant. Synthetic strategies for efficiently producing alkyl-quinones are discussed in the context of selecting optimum radical precursors and initiators depending on quinone identity and functional groups present.

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Tiruye, Hiwot M., Solon Economopoulos, and Kåre B. Jørgensen. "Synthesis of polycyclic aromatic quinones by continuous flow electrochemical oxidation: anodic methoxylation of polycyclic aromatic phenols (PAPs)." Beilstein Journal of Organic Chemistry 20 (July 24, 2024): 1746–57. http://dx.doi.org/10.3762/bjoc.20.153.

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The electrochemical oxidation of polycyclic aromatic phenols (PAPs) has been developed in a microfluidic cell to synthesize polycyclic aromatic quinones (PAQs). Methanol was used as nucleophile to trap the phenoxonium cation formed in the oxidation as an acetal, that later were hydrolysed to the quinone. Formation of hydrogen gas as the cathode reaction caused challenges in the flow cell and were overcome by recycling the reaction mixture through the cell at increased flow rate several times. The specific quinones formed were guided by the position of an initial hydroxy group on the polycyclic aromatic hydrocarbon. An available para-position in the PAPs gave p-quinones, while hydroxy groups in the 2- or 3-position led to o-quinones. The substrates were analysed by cyclic voltammetry for estitmation of the HOMO/LUMO energies to shed more light on this transformation. The easy separation of the supporting electrolyte from the product will allow recycling and makes this a green transformation.

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Silva, Raquel L., Daniel P. Demarque, Renata G. Dusi, João Paulo B. Sousa, Lorena C. Albernaz, and Laila S. Espindola. "Residual Larvicidal Activity of Quinones against Aedes aegypti." Molecules 25, no. 17 (August 31, 2020): 3978. http://dx.doi.org/10.3390/molecules25173978.

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The number of documented dengue cases has increased dramatically in recent years due to transmission through the Aedes aegypti mosquito bite. Vector control remains the most effective measure to protect against this and other arboviral diseases including Zika, chikungunya and (urban) yellow fever, with an established vaccine only available for yellow fever. Although the quinone class shows potential as leading compounds for larvicide development, limited information restricts the development of optimized structures and/or formulations. Thus, in this contribution we investigated the larvicidal and pupicidal activity of three quinone compounds isolated from a Connarus suberosus root wood ethyl acetate extract together with 28 quinones from other sources. Eight quinones demonstrated larvicidal activity, of which tectoquinone (4) proved to be the most active (LC50 1.1 µg/mL). The essential residual effect parameter of four of these quinones was evaluated in laboratory trials, with tectoquinone (4) and 2-ethylanthraquinone (7) presenting the most prolonged activity. In small-scale field residual tests, tectoquinone (4) caused 100% larvae mortality over 5 days, supporting its selection for formulation trials to develop a prototype larvicide to control Ae. aegypti.

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Sladic, Dusan, Irena Novakovic, Zoran Vujcic, Tatjana Bozic, Natasa Bozic, Dragan Milic, Bogdan Solaja, and Miroslav Gasic. "Protein covalent modification of biologically active quinones." Journal of the Serbian Chemical Society 69, no. 11 (2004): 901–7. http://dx.doi.org/10.2298/jsc0411901s.

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The avarone/avarol quinone/hydroquinone couple shows considerable antitumor activity. In this work, covalent modification of ?-lactoglobulin by avarone and its derivatives as well as by the synthetic steroidal quinone 2,5(10)-estradiene- 1,4,17-trione and its derivatives were studied. The techniques for studying chemical modification of ?-lactoglobulin by quinones were: UV/Vis spectrophotometry, SDS PAGE and isoelectrofocusing. SDS PAGE results suggest that polymerization of the protein occurs. It could be seen that the protein of 18 kD gives the bands of 20 kD, 36 kD, 40 kD, 45 kD, 64 kD and 128 kD depending on modification agent. The shift of the pI of the protein (5.4) upon modification toward lower values (from pI 5.0 to 5.3) indicated that lysine amino groups are the principal site of the reaction of ?-lactoglobulin with the quinones.

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25

Hiraishi, Akira, Taichi Umezawa, Hiroyuki Yamamoto, Kenji Kato, and Yonosuke Maki. "Changes in Quinone Profiles of Hot Spring Microbial Mats with a Thermal Gradient." Applied and Environmental Microbiology 65, no. 1 (January 1, 1999): 198–205. http://dx.doi.org/10.1128/aem.65.1.198-205.1999.

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ABSTRACT The respiratory and photosynthetic quinones of microbial mats which occurred in Japanese sulfide-containing neutral-pH hot springs at different temperatures were analyzed by spectrochromatography and mass spectrometry. All of the microbial mats that developed at high temperatures (temperatures above 68°C) were so-called sulfur-turf bacterial mats and produced methionaquinones (MTKs) as the major quinones. A 78°C hot spring sediment had a similar quinone profile.Chloroflexus-mixed mats occurred at temperatures of 61 to 65°C and contained menaquinone 10 (MK-10) as the major component together with significant amounts of either MTKs or plastoquinone 9 (PQ-9). The sunlight-exposed biomats growing at temperatures of 45 to 56°C were all cyanobacterial mats, in which the photosynthetic quinones (PQ-9 and phylloquinone) predominated and MK-10 was the next most abundant component in most cases. Ubiquinones (UQs) were not found or were detected in only small amounts in the biomats growing at temperatures of 50°C and above, whereas the majority of the quinones of a purple photosynthetic mat growing at 34°C were UQs. A numerical analysis of the quinone profiles was performed by using the following three parameters: dissimilarity index (D), microbial divergence index (MDq ), and bioenergetic divergence index (BDq ). A D matrix tree analysis showed that the hot spring mats consisting of the sulfur-turf bacteria, Chloroflexus spp., cyanobacteria, and purple phototrophic bacteria formed distinct clusters. Analyses ofMDq and BDq values indicated that the microbial diversity of hot spring mats decreased as the temperature of the environment increased. The changes in quinone profiles and physiological types of microbial mats in hot springs with thermal gradients are discussed from evolutionary viewpoints.

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Fujisawa, Takuma, Seiji Tsuzuki, Masayoshi Watanabe, and Kazuhide Ueno. "Redox Behavior of Quinones Bearing Ionic Liquid Moiety for Electrochemical CO₂ Capture." ECS Meeting Abstracts MA2024-02, no. 56 (November 22, 2024): 3749. https://doi.org/10.1149/ma2024-02563749mtgabs.

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CCUS (Carbon dioxide Capture, Utilization and Storage), is attracting attention as an effective method for reducing carbon dioxide (CO2) emissions toward carbon neutrality by 2050. Currently, chemical absorption followed by thermal desorption using liquid amine is employed as the CO2 capture and concentration technology. However, low energy efficiency and high cost of the thermal swing process remain to be addressed. CO2 capture driven by renewable electricity represents a promising alternative approach to mitigate CO2 emissions and address climate change. Electrochemically mediated carbon capture can be achieved by developing redox-active CO2 adsorbents, such as quinones. In aprotic electrolytes, reduced quinone species can selectively uptake CO2 from a dilute feed upon electro-reduction via a nucleophilic addition reaction and release a concentrated CO2 upon electrochemical oxidation. However, the low solubility of quinones in nonaqueous solvents limits their total CO2 carrying capacity in the system. We synthesized a salt of imidazolium modified anthraquinone with ionic liquid-like structure to address the solubility issue. The synthesized cationic quinone derivatives showed more than 100 times higher solubility and high ionic conductivity as well as electrochemically reversible CO2 adsorption-desorption. In addition, we synthesized anionic quinone derivatives, anthraquinone with sulfonate (SO3 −) moiety, by one-step salt metathesis reaction, and confirmed that the negatively charged quinones is also applicable to the electrochemical CO2 capture. We report the electrochemical CO2 capture-release behaviors of the ionic quinones and its monitoring using in situ spectroscopic analysis with the aid of density functional theory calculations. Reference: Iida, S. Kondou, S. Tsuzuki, M. Tashiro, N. Shida, K. Motokura, K. Dokko, M. Watanabe, K. Ueno, J. Phys. Chem. C, 2023, 127, 10077.

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Landa, Premysl, Zsofia Kutil, Veronika Temml, Jan Malik, Ladislav Kokoska, Ute Widowitz, Marie Pribylova, et al. "Inhibition of In Vitro Leukotriene B4 Biosynthesis in Human Neutrophil Granulocytes and Docking Studies of Natural Quinones." Natural Product Communications 8, no. 1 (January 2013): 1934578X1300800. http://dx.doi.org/10.1177/1934578x1300800124.

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Quinones are compounds frequently contained in medicinal plants used for the treatment of inflammatory diseases. Therefore, the impact of plant-derived quinones on the arachidonic acid metabolic pathway is worthy of investigation. In this study, twenty-three quinone compounds of plant origin were tested in vitro for their potential to inhibit leukotriene B4 (LTB4) biosynthesis in activated human neutrophil granulocytes with 5-lipoxygenase (5-LOX) activity. The benzoquinones primin (3) and thymohydroquinone (4) (IC50 = 4.0 and 4.1 μM, respectively) showed activity comparable with the reference inhibitor zileuton (IC50 = 4.1 μM). Moderate activity was observed for the benzoquinone thymoquinone (2) (IC50 = 18.2 μM) and the naphthoquinone shikonin (1) (IC50 = 24.3 μM). The anthraquinone emodin and the naphthoquinone plumbagin (5) displayed only weak activities (IC50 > 50 μM). The binding modes of the active compounds were further evaluated in silico by molecular docking to the human 5-LOX crystal structure. This process supports the biological data and suggested that, although the redox potential is responsible for the quinone's activity on multiple targets, in the case of 5-LOX the molecular structure plays a vital role in the inhibition. The obtained results suggest primin as a promising compound for the development of dual COX-2/5-LOX inhibitors.

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Phan, Katherine, Emily E. Lessard, Joseph A. Reed, Meredith G. Warsen, Soren Zimmer, and Lisa M. Landino. "Concurrent Photooxidation and Photoreduction of Catechols and Para-Quinones by Chlorophyll Metabolites." Photochem 4, no. 3 (August 15, 2024): 346–60. http://dx.doi.org/10.3390/photochem4030021.

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Photosynthesis is initiated when the sun’s light induces electron transfer from chlorophyll to plastoquinone, a para-quinone. While photosynthesis occurs in the intact chloroplasts of living plants, similar photochemical reactions between dietary chlorophyll metabolites and quinones are likely and may affect health outcomes. Herein, we continue our studies of the direct photoreduction of para-quinones and ortho-quinones that were generated by the photo-oxidation of catechols. Chlorophyll metabolites, including pheophorbide A, chlorin e6, and pyropheophorbide A, as well as methylene blue were employed as photosensitizers. We detected hydrogen peroxide using horseradish peroxidase following the photo-oxidation of the catechol dopamine, even in the presence of EDTA, a tertiary amine electron donor. Under ambient oxygen, hydrogen peroxide was also detected after the photoreduction of several para-quinones, including 2,3-dimethoxy-5-methyl-p-benzoquinone (CoQ0), methoxy-benzoquinone, and methyl-benzoquinone. The combinations of methylene blue and EDTA or pheophorbide A and triethanolamine as the electron donor in 20% dimethylformamide were optimized for photoreduction of the para-quinones. Chlorin e6 and pyropheophorbide A were less effective for the photoreduction of CoQ0 but were equivalent to pheophorbide A for generating hydrogen peroxide in photo-oxidation reactions with photosensitizers, oxygen, and triethanolamine. We employed dinitrophenylhydrazine to generate intensely colored adducts of methoxy-benzoquinone, methyl-benzoquinone, and 1,4-benzoquinone.

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29

Tsou, Yun-Jie, Ren-You Guan, and Jeng-Liang Han. "Enantioselective organocatalytic vinylogous aldol-cyclization cascade reaction of 3-alkylidene oxindoles with o-quinones." Organic & Biomolecular Chemistry 19, no. 26 (2021): 5836–43. http://dx.doi.org/10.1039/d1ob00888a.

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A enantioselective organocatalytic vinylogous aldol-cyclization cascade reaction of 3-alkylidene oxindoles to o-quinones afforded chiral spirocyclic o-quinone analogues in good to excellent yields with high enantioselectivities.

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30

Moullet, O., and J. L. Dreyer. "Selective inhibition of adenylate cyclase in bovine cortex by quinones: a novel cellular substrate for quinone cytotoxicity." Biochemical Journal 300, no. 1 (May 15, 1994): 99–106. http://dx.doi.org/10.1042/bj3000099.

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Quinones are widely distributed substances of often potential toxicological significance. On the other hand, cyclic AMP is known to promote a cell-survival response and to retard apoptosis [Berridge, Tan and Hilton (1993) Exp. Hematol. 21, 269-276]. Therefore the effects of quinones on adenylate cyclase were tested. Adenylate cyclase is rapidly inhibited by quinones, with IC50 values of 40-45 microM for p-benzoquinone (BQ) or 200 microM for dichlorophenol-indophenol (DCIP), with 2-substituted quinones being inactive. Membrane solubilization decreases the IC50 values for BQ and DCIP to 18 microM and 40 microM respectively. The inhibition is not affected by GTP, GDP or analogues, or by cholera and pertussis toxins; therefore it is not mediated by a G-protein or the activation of a defined receptor. Further, the inhibition stoichiometrically competes with forskolin activation of adenylate cyclase, equimolar concentrations of quinone and forskolin restoring the enzyme activity to its basal value. Reduction of BQ with sodium dithionite stoichiometrically prevents the inhibition of adenylate cyclase; in turn, oxidation of hydroquinone with ferricyanide fully restores it, indicating that the oxidized state of the quinone is required for inhibition. In addition, BQ is cytotoxic in vivo on HepG2, a human hepatocellular carcinoma cell line, but the effect can be prevented with forskolin. In plasma membranes, BQ tightly binds only one major and two minor proteins; these BQ-binding proteins were purified by means of labelling with [14C]BQ followed by PAGE under native conditions. Together these observations indicate that the action of quinone can be traced to targeting a limited number of proteins at the plasma membrane in a highly selective way and to affecting key enzymes such as adenylate cyclase.

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Gready, JE, K. Hata, S. Sternhell, and CW Tansey. "N.M.R.-Study of Bond Orders in o- and p-Quinone." Australian Journal of Chemistry 43, no. 3 (1990): 593. http://dx.doi.org/10.1071/ch9900593.

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The 4J(Me-CC-H) coupling constant, previously established as a probe of bond order,1-3 was used to examine bond orders in a number of quinones. It was found that the presence of a quinone moiety does not cause bond localization in aromatic rings adjacent to the quinone ring.

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Elgawish, Mohamed Saleh, Naoya Kishikawa, Mohamed A. Helal, Kaname Ohyama, and Naotaka Kuroda. "Molecular modeling and spectroscopic study of quinone–protein adducts: insight into toxicity, selectivity, and reversibility." Toxicology Research 4, no. 4 (2015): 843–47. http://dx.doi.org/10.1039/c5tx00098j.

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The toxicity, reversibility and selectivity of quinone–protein adducts were studied using molecular modeling and molecular spectroscopy. Adduction of quinones with proteins could affect their redox potential, bioavailability, and intracellular distribution.

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Lima, Larissa S., Luiz Cláudio de A. Barbosa, Elson S. de Alvarenga, Antônio J. Demuner, and Antônio A. da Silva. "Synthesis and Phytotoxicity Evaluation of Substituted para-Benzoquinones." Australian Journal of Chemistry 56, no. 6 (2003): 625. http://dx.doi.org/10.1071/ch02032.

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Sorgoleone (1) is one of the major constituents of sorghum root exudates. Sorgoleone is an allelochemical that reduces the growth of broad-leaf plants. The 3,5-dimethoxybenzylic alcohol (3) was used as starting material for the synthesis of 2-methoxy-6-(non-1-yl)benzo-1,4-quinone (9) in 69% yield. Acetylation of (9) with acetic anhydride gave the triacetate (10) in 82% yield. The triacetate (10) was then converted in two steps in 2-hydroxy-5-methoxy-3-(non-1-yl)benzo-1,4-quinone (11) and 2-acetoxy-5-methoxy-3-(non-1-yl)benzo-1,4-quinone (12) in 8% and 37% yield, respectively. Quinone (11) was obtained also by reaction of (12) with DBU in 63% yield. Alkylation of (3) and oxidation with chromic anhydride formed the new quinones (16) (17) and (18) in 23%, 16% and 12% overall yield, respectively. The effect of these quinones and sorgoleone (1) at concentrations of 5.5 μg g–1 on the development of radicle and aerial parts of Cucumis sativus, Brachiaria decumbens, Hyptis lophanta, and Euphorbia heterophylla was tested.

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Boutin, Jean A., Gilles Ferry, and Karine Reybier. "A hypothesis on the equilibrium between dopamine toxicity and detoxification: The roles of NQO2 and UDP-glucuronosyltransferases." Gene & Protein in Disease 2, no. 1 (February 1, 2023): 227. http://dx.doi.org/10.36922/gpd.227.

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NQO2 and tyrosine hydroxylase are co-expressed in dopaminergic neurons. These neurons produce dopamine, a diol, which, under aerobic conditions, can spontaneously revert to the more stable form, the o-quinone. O-quinones are preferred substrates of NQO2 over p-quinones. In ad hoc conditions, NQO2 reduces o-quinones into the original diols, leading to a futile cycle, the endpoint of which is a strong local production of reactive oxygen species that is deadly for the cells. This futile cycle can be interrupted by the conjugation of dopamine with UDP-glucuronic acid, leading to a glucuronide that cannot be part of the cycle because the glucuronide is not a substrate of NQO2. In this paper, we confer whether this futile cycle could be one of the causes of the specific death of dopaminergic neuronal population that is the signature of some degenerative diseases.

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Russell, RA, BA Pilley, RW Irvine, and RN Warrener. "Anthracyclines. XVI. Further Comments Concerning the Phthalide Anion Annelation of Quinone Monoacetals." Australian Journal of Chemistry 40, no. 2 (1987): 311. http://dx.doi.org/10.1071/ch9870311.

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.Yields of tricyclic and tetracyclic quinones prepared by annelation of quinone monoacetals with the anion of 3-phenylsulfonylphthalides are shown to be sensitive to the substituent on both the phthalide and the quinone monoacetal partner. In contrast, reactions with the anions of 3-cyanophthalides afford high yields of condensed products in all cases examined.

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Kianmehr, Ebrahim, Mehran Rezazadeh Khalkhali, Masoud Rezaeefard, Khalid Mohammed Khan, and Seik Weng Ng. "Pd-Catalyzed Dehydrogenative Cross-Coupling of 1,4-Quinones with N,N′-Dialkyluracils." Australian Journal of Chemistry 68, no. 1 (2015): 165. http://dx.doi.org/10.1071/ch14412.

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A straightforward and efficient method for the palladium-catalyzed direct cross-coupling of quinones with N,N′-dialkyluracils via 2-fold C–H activation has been developed to rapidly construct uracil substituted quinone structural motifs.

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Xu, Wei, William R. Dolbier, Jian-Xin Duan, Yian Zhai, Katsu Ogawa, Merle A. Battiste, and Ion Ghiviriga. "Octafluoro[2.2]paracyclophane (AF4) Quinone." Collection of Czechoslovak Chemical Communications 73, no. 12 (2008): 1764–76. http://dx.doi.org/10.1135/cccc20081764.

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Octafluoro[2.2]paracyclophane (AF4) has been oxidized by treatment with HIO3 in CF3CO2H to form the corresponding p-quinone along with a unique triketone. This quinone undergoes reduction to the respective hydroquinone as well as a Diels-Alder reaction with 1,3-cyclohexadiene. Its reduction potential was obtained by cyclic voltammetry and is discussed in the context of other quinones.

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Tanaka, Hitomi, Shosuke Ito, Makoto Ojika, Tomoko Nishimaki-Mogami, Kazunari Kondo, and Kazumasa Wakamatsu. "The Oxidation of Equol by Tyrosinase Produces a Unique Di-ortho-Quinone: Possible Implications for Melanocyte Toxicity." International Journal of Molecular Sciences 22, no. 17 (August 24, 2021): 9145. http://dx.doi.org/10.3390/ijms22179145.

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Equol (7-hydroxy-3-(4′-hydroxyphenyl)-chroman, EQ), one of the major intestinally derived metabolites of daidzein, the principal isoflavane found in soybeans and most soy foods, has recently attracted increased interest as a health-beneficial compound for estrogen-dependent diseases. However, based on its structure with two p-substituted phenols, this study aimed to examine whether EQ is a substrate for tyrosinase and whether it produces o-quinone metabolites that are highly cytotoxic to melanocyte. First, the tyrosinase-catalyzed oxidation of EQ was performed, which yielded three EQ-quinones. They were identified after being reduced to their corresponding catechols with NaBH4 or L-ascorbic acid. The binding of the EQ-quinones to N-acetyl-L-cysteine (NAC), glutathione (GSH), and bovine serum albumin via their cysteine residues was then examined. NAC and GSH afforded two mono-adducts and one di-adduct, which were identified by NMR and MS analysis. It was also found that EQ was oxidized to EQ-di-quinone in cells expressing human tyrosinase. Finally, it was confirmed that the EQ-oligomer, the EQ oxidation product, exerted potent pro-oxidant activity by oxidizing GSH to the oxidized GSSG and concomitantly producing H2O2. These results suggest that EQ-quinones could be cytotoxic to melanocytes due to their binding to cellular proteins.

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Hemmi, Hisashi, Yoshihiro Takahashi, Kyohei Shibuya, Toru Nakayama, and Tokuzo Nishino. "Menaquinone-Specific Prenyl Reductase from the Hyperthermophilic Archaeon Archaeoglobus fulgidus." Journal of Bacteriology 187, no. 6 (March 15, 2005): 1937–44. http://dx.doi.org/10.1128/jb.187.6.1937-1944.2005.

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ABSTRACT Four genes that encode the homologues of plant geranylgeranyl reductase were isolated from a hyperthermophilic archaeon Archaeoglobus fulgidus, which produces menaquinone with a fully saturated heptaprenyl side chain, menaquinone-7(14H). The recombinant expression of one of the homologues in Escherichia coli led to a distinct change in the quinone profile of the host cells, although the homologue is the most distantly related to the geranylgeranyl reductase. The new compounds found in the profile had successively longer elution times than those of ordinary quinones from E. coli, i.e., menaquinone-8 and ubiquinone-8, in high-performance liquid chromatography on a reversed-phase column. Structural analyses of the new compounds by electron impact-mass spectrometry indicated that their molecular masses progressively increase relative to the ordinary quinones at a rate of 2 U but that they still contain quinone head structures, strongly suggesting that the compounds are quinones with partially saturated prenyl side chains. In vitro assays with dithionite as the reducing agent showed that the prenyl reductase is highly specific for menaquinone-7, rather than ubiquinone-8 and prenyl diphosphates. This novel enzyme noncovalently binds flavin adenine dinucleotide, similar to geranylgeranyl reductase, but was not able to utilize NAD(P)H as the electron donor, unlike the plant homologue.

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Takač, Milena Jadrijević-Mladar, Joao Daniel Casimiro Magina, and Tin Takač. "Evaluation of phenylethylamine type entactogens and their metabolites relevant to ecotoxicology – a QSAR study." Acta Pharmaceutica 69, no. 4 (December 1, 2019): 563–84. http://dx.doi.org/10.2478/acph-2019-0038.

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Abstract The impact of the selected entactogens and their o-quinone metabolites on the environment was explored in QSAR studies by the use of predicted molecular descriptors, ADMET properties and environmental toxicity parameters, i.e., acute toxicity in Tetrahymena pyriformis (TOX_ATTP) expressed as Th_pyr_pIGC50/mmol L−1, acute toxicity in Pimephales promelas, the fathead minnow (TOX_FHM) expressed as Minnow LC50/mg L−1, the acute toxicity in Daphnia magna (TOX_DM) expressed as Daphnia LC50/mg L−1 and bioconcentration factor (BCF). The formation of corresponding o-quinones via benzo-dioxo-lone ring, O-demethylenation was predicted as the main metabolic pathway for all entactogens except for 1-(2,2-difluorobenzo[d][1,3]dioxol-5-yl)propan-2-amine (DiFMDA). The least favourable ADMET profile was revealed for N-(1-(benzo[d][1,3]dioxol-5-yl)propan-2-yl)-O-methylhydroxylamine (MDMEO). QSAR studies revealed significant linear correlations between MlogP of entactogens and MlogP of o-quinone metabolites (R = 0.99), and Th_pyr_pIGC50/mmol L−1 (R = 0.94), also their MlogPs with Minnow_LC50/mg L−1 (R = 0.80 and R = 0.78), BCF (R = 0.86 and R = 0.82) and percentage of o-quinones’ yields (R = 0.73 and R = 0.80). Entactogens were predicted as non-biodegradable molecules, whereas the majority of their o-quinones were biodegradable.

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Guin, Partha Sarathi, Saurabh Das, and P. C. Mandal. "Electrochemical Reduction of Quinones in Different Media: A Review." International Journal of Electrochemistry 2011 (2011): 1–22. http://dx.doi.org/10.4061/2011/816202.

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The electron transfer reactions involving quinones, hydroquinones, and catechols are very important in many areas of chemistry, especially in biological systems. The therapeutic efficiency as well as toxicity of anthracycline anticancer drugs, a class of anthraquinones, is governed by their electrochemical properties. Other quinones serve as important functional moiety in various biological systems like electron-proton carriers in the respiratory chain and their involvement in photosynthetic electron flow systems. The present paper summarizes literatures on the reduction of quinones in different solvents under various conditions using different electrochemical methods. The influence of different reaction conditions including pH of the media, nature of supporting electrolytes, nature of other additives, intramolecular or intermolecular hydrogen bonding, ion pair formation, polarity of the solvents, stabilization of the semiquinone and quinone dianion, catalytic property, and adsorption at the electrode surface, are discussed and relationships between reaction conditions and products formed have been presented.

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Kass, G. E., S. K. Duddy, and S. Orrenius. "Activation of hepatocyte protein kinase C by redox-cycling quinones." Biochemical Journal 260, no. 2 (June 1, 1989): 499–507. http://dx.doi.org/10.1042/bj2600499.

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The effects of quinone-generated active oxygen species on rat hepatocyte protein kinase C were investigated. The specific activity of cytosolic protein kinase C was increased 2-3-fold in hepatocytes incubated with the redox-cycling quinones, menadione, duroquinone or 2,3-dimethoxy-1,4-naphthoquinone, without alterations in particulate protein kinase C specific activity or Ca2+- and lipid-independent kinase activities. Redox-cycling quinones did not stimulate translocation of protein kinase C; however, activated protein kinase C was redistributed from cytosol to the particulate fraction when quinone-treated hepatocytes were exposed to 12-O-tetradecanoylphorbol 13-acetate (TPA). Quinone treatment did not alter cytosolic phorbol 12,13-dibutyrate (PDBu) binding capacity, and the cytosol of both control and quinone-treated hepatocytes exhibited a Kd for PDBu binding of 2 nM. Quinone-mediated activation of cytosolic protein kinase C was reversed by incubation with 10 mM-beta-mercaptoethanol, dithiothreitol or GSH, at 4 degrees C for 24 h. Furthermore, protein kinase C specific activity in control cytosol incubated in air increased by over 100% within 3 h; this increase was reversed by thiol-reducing agents. Similarly, incubation of partially-purified rat brain protein kinase C in air, or with low concentrations of GSSG in the presence of GSH, resulted in a 2-2.5-fold increase in Ca2+- and lipid-dependent kinase activity. In contrast with the effects of the redox-cycling quinones, when hepatocytes were treated with the thiol agents N-ethylmaleimide (NEM), p-benzoquinone (pBQ) or p-chloromercuribenzoic acid (pCMB), the cytosolic Ca2+- and lipid-dependent kinase activity was significantly inhibited, but the particulate-associated protein kinase C activity was unaffected. The Ca2+- and lipid-independent kinase activity of both the cytosolic and particulate fractions was significantly stimulated by NEM, but was unaffected by pBQ and pCMB. These results show that hepatocyte cytosolic protein kinase C is activated to a high-Vmax form by quinone-generated active oxygen species, and this effect is due to a reduction-sensitive modification of the thiol/disulphide status of protein kinase C.

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43

Jiao, Wei-Hua, Ting-Ting Xu, Bin-Bin Gu, Guo-Hua Shi, Yan Zhu, Fan Yang, Bing-Nan Han, et al. "Bioactive sesquiterpene quinols and quinones from the marine sponge Dysidea avara." RSC Advances 5, no. 106 (2015): 87730–38. http://dx.doi.org/10.1039/c5ra18876h.

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44

Hui, Pan, Mathieu Branca, Benoît Limoges, and François Mavré. "An autocatalytic organic reaction network based on cross-catalysis." Chemical Communications 57, no. 86 (2021): 11374–77. http://dx.doi.org/10.1039/d1cc05121k.

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A simple autocatalytic organic reaction network based on cross-catalysis is here illustrated. It involves the redox chemistry of quinones and reactive oxygen species, requiring only an pro-quinone boronate probe and ascorbate in an aerated solution.

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45

Liu, Shuai, Tong Shen, Zaigang Luo, and Zhong-Quan Liu. "A free radical alkylation of quinones with olefins." Chemical Communications 55, no. 28 (2019): 4027–30. http://dx.doi.org/10.1039/c9cc01704f.

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We demonstrated herein an Fe(iii)-mediated radical alkylation of quinones. A wide range of bioactive molecules with quinone motifs can be rapidly synthesized by using readily available and inexpensive NaBH₄/NaBD₄ with alkenes at room temperature under open flask conditions.

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46

Wiraswati, Hesti L., Fida M. Warganegara, Akhmaloka Akhmaloka, and Muhamad A. Martoprawiro. "Molecular Docking Studies of ROS Agent from Quinone Family to Reductase Enzymes:Implication in Finding Anticancer Drug Candidate." Biomedical and Pharmacology Journal 14, no. 02 (June 30, 2021): 681–89. http://dx.doi.org/10.13005/bpj/2170.

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Understanding the metabolism of cytotoxic compounds of quinone family is importance in cancer therapy because they have been successfully explored for their anti-tumor activity. Quinone which form radical semiquinone (by reductase enzymes) to generate Reactive Oxygen Species (ROS) is associated to be anticancer drug candidate. However, molecular mechanism of those compounds to reductase enzymes has not yet clearly understood.This study aimed to understand molecular interaction of quinones to oxidoreductase enzymes such as cytochrome P450 reductase or ubiquinone reductase (NQO1), or apoptosis inducing factor (AIF) which is recently reported as NADH:quinone reductase. In silico approach was applied to find the best affinity of each compound to enzymes. Optimize ligands were employed using Marvin sketch program. Molecular interaction using autodockvina software was built to measure important residues for quinone reduction. Docking analysis showed that generally quinones prefer bound to cytochrome P450 reductase rather than NQO1 or AIF. The number of ring seems affect to the affinity, but not for its functional groups. Residues analysis confirmed that reduction of quinone is NAD(P)H: dependent. The result revealedthat all ligands have high possibility to compete with their redox coupleswhich is needed in its capacity as an anti-cancer drug.

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47

Giulivi, C., and E. Cadenas. "One- and two-electron reduction of 2-methyl-1,4-naphthoquinone bioreductive alkylating agents: kinetic studies, free-radical production, thiol oxidation and DNA-strand-break formation." Biochemical Journal 301, no. 1 (July 1, 1994): 21–30. http://dx.doi.org/10.1042/bj3010021.

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The one- and two-electron enzymic reduction of the bioreductive alkylating agents 2-methylmethoxynaphthoquinone (quinone I) and 2-chloromethylnaphthoquinone (quinone II) was studied with purified NADPH-cytochrome P-450 reductase and DT-diaphorase respectively, and characterized in terms of kinetic constants, oxyradical production, thiol oxidation and DNA-strand-break formation. The catalytic-centre activity values indicated that DT-diaphorase catalysed the reduction of quinone I far more efficiently than NADPH-cytochrome P-450 reductase, although the Km values of the two enzymes for this quinone were similar (1.2-3.0 microM). The one-electron-transfer flavoenzyme also catalysed the reduction of quinone II, but the behaviour of DT-diaphorase towards this quinone did not permit calculation of kinetic constants. A salient feature of the redox transitions caused by the one- and two-electron catalysis of these quinones was the different contributions of disproportionation and autoxidation reactions respectively. In the former case, about 26% of NADPH consumed was accounted for in terms of autoxidation (as H2O2 formation), whereas in the latter, the autoxidation component accounted for most (98%) of the NADPH consumed. This difference was abrogated by superoxide dismutase, which enhanced autoxidation during NADPH-cytochrome P-450 catalysis to a maximal value. E.s.r. analysis indicated the formation of superoxide radicals, the signal of which was suppressed by superoxide dismutase and unaffected by catalase. The one- and two-electron reduction of these quinones in the presence of GSH was accompanied by formation of thiyl radicals. Although superoxide dismutase suppressed the thiol radical e.s.r. signal in both instances, the enzyme enhanced GSSG accumulation during NADPH-cytochrome P-450 catalysis of quinone I, whereas it inhibited GSSG formation during reduction of the quinone by DT-diaphorase. One- and two-electron reduction of quinone I led to calf thymus DNA-strand-break formation, a process that (a) was substantially decreased in experiments performed with dialysed DNA and in the presence of desferal and (b) was partially sensitive to superoxide dismutase and/or catalase. These findings are rationalized in terms of the occurrence of metal ions ligated to DNA, protecting against the toxic effects of superoxide radicals generated during enzymic reduction of quinones.

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Koike, Hiroyuki, Yasuhiro Kashino, and Kazuhiko Satoh. "Interactions of Halogenated Benzoquinones with the Non-Heme Iron (Q400) in Photosystem II." Zeitschrift für Naturforschung C 48, no. 3-4 (April 1, 1993): 168–73. http://dx.doi.org/10.1515/znc-1993-3-410.

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Abstract Interactions of halogenated benzoquinones with the acceptor side of Photosystem (PS) II were studied by measuring fluorescence induction curves and flash-induced absorbance changes in PS II particles isolated from Synechococcus vulcanus. Following results were obtained: 1) Addition of some halogenated benzoquinones prior to 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) in the dark increased the area above the fluorescence induction curve (work integral) by a factor of two. 2) Based on the ability to increase the fluorescence work integral, halogenated benzoquinones could be divided into two groups. 3) 2,6-Dichlorobenzo-quinone (2,6-DCBQ), trichlorobenzoquinone (TCBQ) and tetrahalogenated benzoquinones except tetrafluorobenzoquinone (fluoranil) (group A) increased the work integral, but 2,5-DCBQ and fluoranil (group B) did not. 4) Rapid reoxidation of QA- was observed in the presence of quinones which belong to group A.These results were interpreted in terms of dark oxidation of by quinones belonging to group A. Possible mechanisms of oxidation of Q400 by these quinones in the dark are discussed.

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Sekulic, Tatjana, Lj V. Vujisic, B. P. M. Curcic, B. M. Mandic, D. Z. Antic, Snezana Trifunovic, D. M. Godjevac, Vlatka Vajs, V. T. Tomic, and S. E. Makarov. "Quinones and non-quinones from the defensive secretion of Unciger transsilvanicus (Verhoeff, 1899) (Diplopoda, Julida, Julidae), from Serbia." Archives of Biological Sciences 66, no. 1 (2014): 385–90. http://dx.doi.org/10.2298/abs1401385s.

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A complex mixture of compounds was identified from the secretion of specimens of Unciger transsilvanicus. Phenol and p-cresol were detected for the first time in the family Julidae, and for the second time in the order Julida. Thirteen quinones were identified, with a great relative abundance of toloquinone and 2-methoxy-3-methyl-1,4-benzoquinone. Hydroquinone was detected for the first time in the order Julida. Besides these compounds, isopentyl hexacosatetraenoate and isopentyl esters of saturated and unsaturated fatty acids with chain lengths from C14 to C20were identified. The most abundant non-quinone compound was isopentyl eicosenoate. The relative abundance of quinone and non-quinone in the defensive fluid of U. transsilvanicus was 77% and 23%, respectively. The phylogenetic importance of the registered compounds is briefly discussed.

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Wang, Zhen-Hua, Xiao-Hui Fu, Qun Li, Yong You, Lei Yang, Jian-Qiang Zhao, Yan-Ping Zhang, and Wei-Cheng Yuan. "Recent Advances in the Domino Annulation Reaction of Quinone Imines." Molecules 29, no. 11 (May 24, 2024): 2481. http://dx.doi.org/10.3390/molecules29112481.

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Quinone imines are important derivatives of quinones with a wide range of applications in organic synthesis and the pharmaceutical industry. The attack of nucleophilic reagents on quinone imines tends to lead to aromatization of the quinone skeleton, resulting in both the high reactivity and the unique reactivity of quinone imines. The extreme value of quinone imines in the construction of nitrogen- or oxygen-containing heterocycles has attracted widespread attention, and remarkable advances have been reported recently. This review provides an overview of the application of quinone imines in the synthesis of cyclic compounds via the domino annulation reaction.

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Journal articles on the topic 'Quinones'

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