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Alfieri ML, Panzella L, Amorati R, Cariola A, Valgimigli L, Napolitano A. Role of Sulphur and Heavier Chalcogens on the Antioxidant Power and Bioactivity of Natural Phenolic Compounds. Biomolecules 2022; 12:90. [PMID: 35053239 PMCID: PMC8774257 DOI: 10.3390/biom12010090] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 01/03/2022] [Accepted: 01/04/2022] [Indexed: 02/06/2023] Open
Abstract
The activity of natural phenols is primarily associated to their antioxidant potential, but is ultimately expressed in a variety of biological effects. Molecular scaffold manipulation of this large variety of compounds is a currently pursued approach to boost or modulate their properties. Insertion of S/Se/Te containing substituents on phenols may increase/decrease their H-donor/acceptor ability by electronic and stereo-electronic effects related to the site of substitution and geometrical constrains. Oxygen to sulphur/selenium isosteric replacement in resveratrol or ferulic acid leads to an increase in the radical scavenging activity with respect to the parent phenol. Several chalcogen-substituted phenols inspired by Vitamin E and flavonoids have been prepared, which in some cases prove to be chain-breaking antioxidants, far better than the natural counterparts. Conjugation of catechols with biological thiols (cysteine, glutathione, dihydrolipoic acid) is easily achieved by addition to the corresponding ortho-quinones. Noticeable examples of compounds with potentiated antioxidant activities are the human metabolite 5-S-cysteinyldopa, with high iron-induced lipid peroxidation inhibitory activity, due to strong iron (III) binding, 5-S-glutathionylpiceatannol a most effective inhibitor of nitrosation processes, and 5-S-lipoylhydroxytyrosol, and its polysulfides that proved valuable oxidative-stress protective agents in various cellular models. Different methodologies have been used for evaluation of the antioxidant power of these compounds against the parent compounds. These include kinetics of inhibition of lipid peroxidation alkylperoxyl radicals, common chemical assays of radical scavenging, inhibition of the OH• mediated hydroxylation/oxidation of model systems, ferric- or copper-reducing power, scavenging of nitrosating species. In addition, computational methods allowed researchers to determine the Bond Dissociation Enthalpy values of the OH groups of chalcogen modified phenolics and predict the best performing derivative. Finally, the activity of Se and Te containing compounds as mimic of glutathione peroxidase has been evaluated, together with other biological activities including anticancer action and (neuro)protective effects in various cellular models. These and other achievements are discussed and rationalized to guide future development in the field.
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Affiliation(s)
- Maria Laura Alfieri
- Department of Chemical Sciences, University of Naples “Federico II”, Via Cintia 21, I-80126 Naples, Italy; (M.L.A.); (L.P.)
| | - Lucia Panzella
- Department of Chemical Sciences, University of Naples “Federico II”, Via Cintia 21, I-80126 Naples, Italy; (M.L.A.); (L.P.)
| | - Riccardo Amorati
- Department of Chemistry “Giacomo Ciamician”, University of Bologna, Via S. Giacomo 11, I-40126 Bologna, Italy; (R.A.); (A.C.)
| | - Alice Cariola
- Department of Chemistry “Giacomo Ciamician”, University of Bologna, Via S. Giacomo 11, I-40126 Bologna, Italy; (R.A.); (A.C.)
| | - Luca Valgimigli
- Department of Chemistry “Giacomo Ciamician”, University of Bologna, Via S. Giacomo 11, I-40126 Bologna, Italy; (R.A.); (A.C.)
| | - Alessandra Napolitano
- Department of Chemical Sciences, University of Naples “Federico II”, Via Cintia 21, I-80126 Naples, Italy; (M.L.A.); (L.P.)
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Kim E, Panzella L, Napolitano A, Payne GF. Redox Activities of Melanins Investigated by Electrochemical Reverse Engineering: Implications for their Roles in Oxidative Stress. J Invest Dermatol 2020; 140:537-543. [DOI: 10.1016/j.jid.2019.09.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 09/05/2019] [Accepted: 09/25/2019] [Indexed: 12/14/2022]
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Ryu JH, Messersmith PB, Lee H. Polydopamine Surface Chemistry: A Decade of Discovery. ACS APPLIED MATERIALS & INTERFACES 2018; 10:7523-7540. [PMID: 29465221 PMCID: PMC6320233 DOI: 10.1021/acsami.7b19865] [Citation(s) in RCA: 823] [Impact Index Per Article: 137.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Polydopamine is one of the simplest and most versatile approaches to functionalizing material surfaces, having been inspired by the adhesive nature of catechols and amines in mussel adhesive proteins. Since its first report in 2007, a decade of studies on polydopamine molecular structure, deposition conditions, and physicochemical properties have ensued. During this time, potential uses of polydopamine coatings have expanded in many unforeseen directions, seemingly only limited by the creativity of researchers seeking simple solutions to manipulating surface chemistry. In this review, we describe the current state of the art in polydopamine coating methods, describe efforts underway to uncover and tailor the complex structure and chemical properties of polydopamine, and identify emerging trends and needs in polydopamine research, including the use of dopamine analogs, nitrogen-free polyphenolic precursors, and improvement of coating mechanical properties.
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Affiliation(s)
- Ji Hyun Ryu
- Department of Carbon Fusion Engineering, Wonkwang University, Iksan, Jeonbuk 54538, South Korea
| | - Phillip B. Messersmith
- Departments of Bioengineering and Materials Science and Engineering, University of California, Berkeley, 210 Hearst Mining Building, Berkeley, California 94720-1760, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Haeshin Lee
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), 291 University Road, Daejeon 34141, South Korea
- Center for Nature-inspired Technology (CNiT), KAIST Institute of NanoCentury, 291 University Road, Daejeon 34141, South Korea
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Liu Z, Ma H, Liu J, Xing L, Cheng L, Yang J, Mao B, Zhang Q. A low-cost clay-based heterogeneous Fenton-like catalyst: Activation, efficiency enhancement, and mechanism study. ASIA-PAC J CHEM ENG 2017. [DOI: 10.1002/apj.2156] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Zhengjiang Liu
- Key Lab of Industrial Catalysis of the Inner Mongolia Autonomous Region; Inner Mongolia University of Technology; Hohhot 010051 China
| | - Huiyan Ma
- Key Lab of Industrial Catalysis of the Inner Mongolia Autonomous Region; Inner Mongolia University of Technology; Hohhot 010051 China
| | - Juming Liu
- Key Lab of Industrial Catalysis of the Inner Mongolia Autonomous Region; Inner Mongolia University of Technology; Hohhot 010051 China
| | - Lei Xing
- Institute of Green Chemistry and Chemical Technology; Jiangsu University; Zhenjiang 212013 China
| | - Lin Cheng
- Key Lab of Industrial Catalysis of the Inner Mongolia Autonomous Region; Inner Mongolia University of Technology; Hohhot 010051 China
| | - Jucai Yang
- Key Lab of Industrial Catalysis of the Inner Mongolia Autonomous Region; Inner Mongolia University of Technology; Hohhot 010051 China
| | - Baodong Mao
- School of Chemistry and Chemical Engineering; Jiangsu University; Zhenjiang 212013 China
| | - Qiancheng Zhang
- Key Lab of Industrial Catalysis of the Inner Mongolia Autonomous Region; Inner Mongolia University of Technology; Hohhot 010051 China
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Napolitano A, Panzella L, Monfrecola G, d'Ischia M. Pheomelanin-induced oxidative stress: bright and dark chemistry bridging red hair phenotype and melanoma. Pigment Cell Melanoma Res 2014; 27:721-33. [PMID: 24814217 DOI: 10.1111/pcmr.12262] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Accepted: 05/08/2014] [Indexed: 01/20/2023]
Abstract
The complex interplay of genetic and epigenetic factors linking sun exposure to melanoma in the red hair phenotype hinges on the peculiar physical and chemical properties of pheomelanins and the underlying biosynthetic pathway, which is switched on by the effects of inactivating polymorphisms in the melanocortin 1 receptor gene. In addition to the long recognized UV-dependent pathways of toxicity and cell damage, a UV-independent pro-oxidant state induced by pheomelanin within the genetically determined background of the red hair phenotype has recently been disclosed. This review provides a detailed discussion of the possible UV-dependent and UV-independent chemical mechanisms underlying pheomelanin-mediated oxidative stress, with special reference to the oxygen-dependent depletion of glutathione and other cell antioxidants. The new concept of pheomelanin as a 'living' polymer and biocatalyst that may grow by exposure to monomer building blocks and may trigger autooxidative processes is also discussed. As a corollary, treatment of inflammatory skin diseases in RHP patients is briefly commented. Finally, possible concerted strategies for melanoma prevention in the red hair phenotype are proposed.
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Panzella L, Leone L, Greco G, Vitiello G, D'Errico G, Napolitano A, d'Ischia M. Red human hair pheomelanin is a potent pro-oxidant mediating UV-independent contributory mechanisms of melanomagenesis. Pigment Cell Melanoma Res 2014; 27:244-52. [PMID: 24387634 DOI: 10.1111/pcmr.12199] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Accepted: 11/26/2013] [Indexed: 12/29/2022]
Abstract
The highest incidence of melanoma in red haired individuals is attributed to the synthesis and phototoxic properties of pheomelanin pigments. Recently, pheomelanin has also been implicated in UV-independent pathways of oxidative stress; however, the underlying mechanisms have remained uncharted. Herein, we disclose the unprecedented property of purified red human hair pheomelanin (RHP) to promote (i) the oxygen-dependent depletion of major cell antioxidants, for example glutathione and NADH; (ii) the autoxidative formation of melanin pigments from their precursors. RHP would thus behave as a unique 'living' polymer and biocatalyst that may grow by simple exposure to monomer building blocks and may trigger autoxidative processes. These results yield new clues as to the origin of the pro-oxidant state in the red hair phenotype, uncover non-enzymatic pathways of melanogenesis, and pave the way to innovative strategies for melanoma prevention.
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Affiliation(s)
- Lucia Panzella
- Department of Chemical Sciences, University of Naples Federico II, Naples, Italy
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Panzella L, Verotta L, Goya L, Ramos S, Martín MA, Bravo L, Napolitano A, d'Ischia M. Synthesis and bioactivity profile of 5-s-lipoylhydroxytyrosol-based multidefense antioxidants with a sizeable (poly)sulfide chain. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2013; 61:1710-1717. [PMID: 23256907 DOI: 10.1021/jf302690c] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Novel polyfunctionalized antioxidants, 5-S-lipoylhydroxytyrosol (1) and its disulfide 2, trisulfide 3, and tetrasulfide 4, were prepared from tyrosol and dihydrolipoic acid in the presence, when appropriate, of sulfur. Compound 1 exhibited significant activity in the ferric reducing/antioxidant power (FRAP) assay (1.60 Trolox equiv), whereas polysulfides 2-4 were more efficient in the DPPH reduction assay (88-93% reduction vs 68% by Trolox). At 10 μM concentration, all compounds 1-4 proved to be efficient hydroxyl radical scavengers (56-69% inhibition) in a Fenton reaction assay. When administered to human HepG2 cells, 1-4 proved to be nontoxic and exhibited marked protective effects against reactive oxygen species (ROS) generation (60-84% inhibition at 1 μM concentration) and cell damage induced by 400 μM tert-butylhydroperoxide. All compounds 1-4 exhibited overall greater antioxidant activity than hydroxytyrosol.
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Affiliation(s)
- Lucia Panzella
- Department of Chemical Sciences, University of Naples Federico II, Naples, Italy.
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Slominski A, Zmijewski MA, Pawelek J. L-tyrosine and L-dihydroxyphenylalanine as hormone-like regulators of melanocyte functions. Pigment Cell Melanoma Res 2012; 25:14-27. [PMID: 21834848 PMCID: PMC3242935 DOI: 10.1111/j.1755-148x.2011.00898.x] [Citation(s) in RCA: 334] [Impact Index Per Article: 27.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
There is evidence that L-tyrosine and L-dihydroxyphenylalanine (L-DOPA), besides serving as substrates and intermediates of melanogenesis, are also bioregulatory agents acting not only as inducers and positive regulators of melanogenesis but also as regulators of other cellular functions. These can be mediated through action on specific receptors or through non-receptor-mediated mechanisms. The substrate induced (L-tyrosine and/or L-DOPA) melanogenic pathway would autoregulate itself as well as regulate the melanocyte functions through the activity of its structural or regulatory proteins and through intermediates of melanogenesis and melanin itself. Dissection of regulatory and autoregulatory elements of this process may elucidate how substrate-induced autoregulatory pathways have evolved from prokaryotic or simple eukaryotic organisms to complex systems in vertebrates. This could substantiate an older theory proposing that receptors for amino acid-derived hormones arose from the receptors for those amino acids, and that nuclear receptors evolved from primitive intracellular receptors binding nutritional factors or metabolic intermediates.
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Affiliation(s)
- Andrzej Slominski
- Department of Pathology and Laboratory Medicine, University of Tennessee, Memphis, TN, USA.
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Takadera T, Koriyama Y, Kimura T, Kato S. 5-S-GAD Attenuates Fe2+-Induced Lipid Peroxidation and Cell Death in a Neuronal Cell Model. Neurotox Res 2010; 20:26-31. [DOI: 10.1007/s12640-010-9218-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2010] [Revised: 08/17/2010] [Accepted: 08/18/2010] [Indexed: 10/19/2022]
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Panzella L, Szewczyk G, D’Ischia M, Napolitano A, Sarna T. Zinc-induced Structural Effects Enhance Oxygen Consumption and Superoxide Generation in Synthetic Pheomelanins on UVA/Visible Light Irradiation†. Photochem Photobiol 2010; 86:757-64. [DOI: 10.1111/j.1751-1097.2010.00726.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Greco G, Wakamatsu K, Panzella L, Ito S, Napolitano A, d’Ischia M. Isomeric cysteinyldopas provide a (photo)degradable bulk component and a robust structural element in red human hair pheomelanin. Pigment Cell Melanoma Res 2009; 22:319-27. [DOI: 10.1111/j.1755-148x.2009.00561.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Akiyama N, Umeda IO, Sogo S, Nishigori H, Tsujimoto M, Natori S. 5-S-GAD, a novel radical scavenging compound, prevents lens opacity development. Free Radic Biol Med 2009; 46:511-9. [PMID: 19084592 DOI: 10.1016/j.freeradbiomed.2008.11.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2008] [Revised: 11/11/2008] [Accepted: 11/12/2008] [Indexed: 11/22/2022]
Abstract
The ability of N-beta-alanyl-5-S-glutathionyl-3,4-dihydroxyphenylalanine (5-S-GAD)-a novel catechol derivative isolated from an insect as an antibacterial substance-to scavenge free radicals and prevent cataract progression was examined. 5-S-GAD scavenged 1,1-diphenylpicrylhydrazyl (DPPH) and superoxide anions (O(2)(*)(-)), and inhibited lipid peroxidation. It also significantly inhibited the onset of glucocorticoid-induced lens opacification in chick embryos. These effects of 5-S-GAD were stronger than those of N-acetylcarnosine and TEMPOL, which are reported to be effective radical scavengers in the prevention of cataract progression. 5-S-GAD clearly delayed the maturation of cataracts induced by diamide in cultured lenses of rats. Daily instillation of 5-S-GAD retarded the development of lens opacity in galactose-fed rats. Biochemical analysis of the lenses revealed that 20-kDa proteins, presumably consisting of alpha-crystallin, were the most susceptible to oxidative stress, which leads to the carbonylation of the side chains of these proteins. alpha-Crystallin carbonylation induced by diamide or galactose was notably inhibited by 5-S-GAD in a dose-dependent manner. Our results show that 5-S-GAD prevents acute lens opacification in these short-term experimental models, possibly in part by virtue of its antioxidative property, and 5-S-GAD is expected to have long-term pharmaceutical effects.
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Panzella L, De Lucia M, Napolitano A, d’Ischia M. The first expedient entry to the human melanogen 2-S-cysteinyldopa exploiting the anomalous regioselectivity of 3,4-dihydroxycinnamic acid–thiol conjugation. Tetrahedron Lett 2007. [DOI: 10.1016/j.tetlet.2007.08.098] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Zhang X, Erb C, Flammer J, Nau WM. Absolute Rate Constants for the Quenching of Reactive Excited States by Melanin and Related 5,6-Dihydroxyindole Metabolites: Implications for Their Antioxidant Activity. Photochem Photobiol 2007. [DOI: 10.1562/0031-8655(2000)0710524arcftq2.0.co2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Manini P, Napolitano A, d'Ischia M. Reactions of d-glucose with phenolic amino acids: further insights into the competition between Maillard and Pictet–Spengler condensation pathways. Carbohydr Res 2005; 340:2719-27. [PMID: 16229826 DOI: 10.1016/j.carres.2005.09.021] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2005] [Revised: 09/26/2005] [Accepted: 09/28/2005] [Indexed: 02/02/2023]
Abstract
The reactions of 5-S-cysteinyldopa, L-alpha-methyldopa and DL-m-tyrosine with D-glucose were investigated at 90 degrees C in phosphate buffer at pH ranging from 5.0 to 9.0. Whereas gave mainly the double Maillard condensation product N,N'-bis(1''-deoxy-D-fructos-1''-yl)-5-S-cysteinyldopa, as an inseparable mixture of beta-D-fructopyranosyl and alpha,beta-D-fructofuranosyl derivatives, 2 and 3 gave both Maillard and Pictet-Spengler products, although to different extents and with different regio- and stereochemistry. A peculiar pattern of reactivity was displayed by which gave, besides the Maillard product and the expected 6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline C-1 diastereoisomeric pairs, the unprecedented 7,8-dihydroxy-1,2,3,4-tetrahydroisoquinoline derivative via the ortho cyclization pathway. Pictet-Spengler cyclization of 2 and 3 proceeded with Felkin-Anh-type asymmetric induction, favouring the 1R isomer throughout the pH range 5.0-9.0. These results, which highlight the first example of carbohydrate-derived 7,8-dihydroxytetrahydroisoquinoline, provide new insights into the factors governing competition between Maillard and Pictet-Spengler condensation pathways.
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Affiliation(s)
- Paola Manini
- Department of Organic Chemistry and Biochemistry, University of Naples Federico II, Complesso Universitario Monte Sant'Angelo, Via Cinthia 4, I-80126 Naples, Italy
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Di Donato P, Napolitano A, Prota G. Metal ions as potential regulatory factors in the biosynthesis of red hair pigments: a new benzothiazole intermediate in the iron or copper assisted oxidation of 5-S-cysteinyldopa. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1571:157-66. [PMID: 12049796 DOI: 10.1016/s0304-4165(02)00212-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In the presence of iron or copper ions, the course of the oxidation in air of 5-S-cysteinyldopa (1), the main biosynthetic precursor of pheomelanins and trichochromes, was markedly changed affording two main products. One of these was identified as the oxobenzothiazine 8, previously obtained under nonphysiologically relevant conditions, while the other was characterized as the novel hydroxybenzothiazole 9. Besides 8 and 9, carboxylated and noncarboxylated benzothiazine products were obtained by persulfate oxidation of 1 in the presence of iron or copper ions. The ratio of formation yields of carboxylated/noncarboxylated benzothiazines, determined after reduction of the mixture, was lower than that of the control reaction run in the absence of metal ions, and much lower than that of the oxidation carried out in the presence of zinc ions, in agreement with a recent report. Notably, 8 and 9 were formed in variable yields under different oxidation conditions including tyrosinase/O(2), peroxidase/hydrogen peroxide, and the hydrogen peroxide/or (9E,11Z,13S)-13-hydroperoxyoctadeca-9,11-dienoic acid/Fe(III) systems. Mechanistic routes to 8 and 9 were proposed based on the results of experiments involving in situ generation of labile benzothiazine intermediates. Overall, these results allow to formulate an improved biosynthetic scheme in which metal ions act as critical regulatory factors determining pheomelanin vs. trichochromes formation.
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Affiliation(s)
- Paola Di Donato
- Department of Organic Chemistry and Biochemistry, University of Naples Federico II, Complesso Universitario Monte S. Angelo, Via Cinthia 4, Italy
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Mosca L, Marcellini S, Perluigi M, Mastroiacovo P, Moretti S, Famularo G, Peluso I, Santini G, De Simone C. Modulation of apoptosis and improved redox metabolism with the use of a new antioxidant formula. Biochem Pharmacol 2002; 63:1305-14. [PMID: 11960607 DOI: 10.1016/s0006-2952(02)00867-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Oxidative stress is involved in the pathogenesis of a wide spectrum of diseases, implicating that strategies directed at counterbalancing oxidative processes could have a role in clinical medicine. There is also an evidence that oxidative stress acts as a major determinant of apoptotic cell death. Many studies have reported favourable effects of antioxidant formulas on several parameters of the oxidant-antioxidant balance, but none of them has focused whether antioxidant formulas could modulate apoptosis. We investigated in 20 healthy individuals the effect of supplementation with a formula containing alpha-tocopherol, alpha-lipoic acid, coenzyme Q(10), carnitines, and selenomethionine, on plasma oxidant status and peroxide levels, erythrocyte antioxidant enzymes, lymphocyte apoptosis, and generation of ROS at the mitochondrial level. Control subjects received only carnitines or an incomplete formula with alpha-tocopherol, alpha-lipoic acid, coenzyme Q(10), and selenomethionine. Supplementation with the complete formula resulted in a significant increase in the plasma antioxidant status that was mirrored by a decrease in blood peroxide levels and a reduced generation of ROS at the mitochondrial level. This was associated with a significant decrease in the frequency of peripheral blood lymphocytes, with either CD4 or CD8 phenotype, undergoing apoptosis. Less consistent results were found when either incomplete formula was used. Our study suggests that supplementation with antioxidant formulas can modulate the process of apoptosis under in vivo conditions. The clinical potential of this strategy in the treatment of diseases with an elevated commitment to apoptosis should be explored.
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Affiliation(s)
- Luciana Mosca
- Department of Biochemical Sciences, Faculty of Medicine, University of Rome La Sapienza, p. le Aldo Moro 5, 00185 Rome, Italy.
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Coccia R, Foppoli C, Blarzino C, De Marco C, Rosei MA. Interaction of enkephalin derivatives with reactive oxygen species. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1525:43-9. [PMID: 11342252 DOI: 10.1016/s0304-4165(00)00169-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The oxidation of opioid peptides by tyrosinase in the presence of an excess of a thiol gives rise to cysteinyldopa derivatives. The major products arising from the reaction between Leu-enkephalin and cysteine are represented by 5-S-cysteinyldopaenkephalin (5-CDenk) and 2-S-cysteinyldopaenkephalin (2-CDenk). The interaction of 5-CDenk and 2-CDenk with reactive oxygen species (ROS) has been studied. These compounds are able to scavenge superoxide anion, hydroxyl and peroxyl radicals as well as to reduce the lipid peroxidation rate induced by ABAP. The scavenging activities in all instances are dose-dependent. In some cases CDenks are more active than compounds recognized as strong radical scavengers, such as Trolox and mannitol. As a result of the action of the Fenton system, the CDenks (as well as the Enks) are oxidized into pigmented derivatives. The possible implications of the interaction of CDenks and Enks with ROS on melanization process in Parkinson's disease are discussed.
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Affiliation(s)
- R Coccia
- Department of Biochemistry Sciences, Univeristy of Rome La Sapienza, Italy
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Napolitano A, Di Donato P, Prota G. New regulatory mechanisms in the biosynthesis of pheomelanins: rearrangement vs. redox exchange reaction routes of a transient 2H-1, 4-benzothiazine-o-quinonimine intermediate. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1475:47-54. [PMID: 10806337 DOI: 10.1016/s0304-4165(00)00053-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Pheomelanins, the typical epidermal pigments of red haired, Celtic-type Caucasians, arise from oxidative cyclization of cysteinyldopas, mainly the 5-S-isomer CD, via 1,4-benzothiazines. However, the mechanism and the relative yields of formation of these intermediates have remained poorly defined. We have now examined the course of the oxidation of CD at physiological pHs, under different reaction conditions. Surprisingly, a consumption of CD far exceeding the stoichiometry of the oxidant was observed at low oxidant-to-substrate ratios, low temperatures and high substrate concentrations. The yields of the 3,4-dihydro-1,4-benzothiazine-3-carboxylic acid DHBCA vs. the non-carboxylated analogue DHB in the oxidation mixture, after NaBH4 reduction, were also found to depend markedly on the reaction conditions. Based on these and other results, a reaction scheme is proposed involving a transient o-quinonimine generated by oxidative cyclization of CD to which three different paths are offered, namely redox exchange with CD to give DHBCA (path A) or intramolecular rearrangement with (path B) or without (path C) decarboxylation, leading to the benzothiazine BTZ and the 3-carboxy analogue BTZCA, respectively. The relative operation of path A vs. path C was assessed by deuterium labeling experiments. These findings point to new mechanisms of regulation of the initial steps of pheomelanogenesis, bearing significant implications on the structure of the final pigment.
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Affiliation(s)
- A Napolitano
- Department of Organic and Biological Chemistry, University of Naples Federico II, Via Mezzocannone 16, I-80134, Naples, Italy
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Zhang X, Erb C, Flammer J, Nau WM. Absolute rate constants for the quenching of reactive excited states by melanin and related 5,6-dihydroxyindole metabolites: implications for their antioxidant activity. Photochem Photobiol 2000; 71:524-33. [PMID: 10818782 DOI: 10.1562/0031-8655(2000)071<0524:arcftq>2.0.co;2] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The triplet-excited state of benzophenone and the singlet-excited state of 2,3-diazabicyclo[2.2.2]oct-2-ene (Fluorazophore-P) have been employed as kinetic probes to obtain information on the antioxidant activity of the skin and eye pigment melanin and its biogenetic precursors 5,6-dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA). The excited states were generated by the laser-flash photolysis technique and their reaction kinetics was examined by time-resolved transient absorption or fluorescence spectroscopy, respectively. The reaction between triplet benzophenone and DHI produced with unit efficiency the corresponding 6O-centered semiquinone radical, which was characterized by its characteristic transient absorption. The quenching rate constants for DHI (3.1-8.4 x 10(9) M-1 s-1) and DHICA (3.3-5.5 x 10(9) M-1 s-1) were near the diffusion-controlled limit, indicating excellent antioxidant properties. Kinetic solvent effects were observed. The reactivity of synthetic melanin, assessed through the quenching rate constant of Fluorazophore-P and normalized to the number of monomer units, was more than one order of magnitude lower (2.7 x 10(8) M-1 s-1) than that of its precursors. The trend of the quenching rate constants, i.e. DHI > DHICA approximately alpha-tocopherol > melanin, along with the preferential solubility of DHICA in aqueous environments, serves to account for several experimental results from biochemical studies on the inhibition of lipid peroxidation by these natural antioxidants.
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Affiliation(s)
- X Zhang
- Departement Chemie, Universität Basel, Switzerland
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Abstract
This paper reviews what is currently known about the redox state of the glutamate synapse and its possible role in modulating synaptic plasticity and thus learning and neurocomputation. The hypothesis is presented that the growth or pruning of the synaptic spine is controlled in part by the balance in the synapse between neurodestructive pro-oxidants (e.g., nitric acid radical and hydrogen peroxide) and neuroprotective antioxidants (e.g., ascorbate and carnosine). In addition, there may be a role for catecholamines, in particular dopamine, related to its role in reinforcement signalling. Activation of the dopamine D2 receptor induces the synthesis of an antioxidant enzyme, possibly catalase. Dopamine may also affect the redox balance in the glutamate synapse directly by diffusion from the adjacent dopaminergic bouton-en-passage. Catecholamines are powerful antioxidants, scavengers of free radicals and iron chelators. Catecholamine-iron complexes are potent dismuters of superoxide ions. Additional agents participating in spine pruning may be neurotoxic catecholamine o-quinones present in the brain. This system may be at fault in schizophrenia and Parkinson's disease. Experiments to test the hypothesis are suggested.
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Huang X, Xu R, Hawley MD, Hopkins TL, Kramer KJ. Electrochemical oxidation of N-acyldopamines and regioselective reactions of their quinones with N-acetylcysteine and thiourea. Arch Biochem Biophys 1998; 352:19-30. [PMID: 9521807 DOI: 10.1006/abbi.1997.0567] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The metabolism of catechols often involves their oxidation to quinones and subsequent nucleophilic addition reactions with sulfur-containing compounds. Adducts formed during these reactions may play important roles in many biological systems. We have studied the electrochemical oxidation of N-acetyldopamine (NADA) and N-beta-alanyldopamine (NBAD) in the presence of two sulfur-centered nucleophiles, N-acetylcysteine (NACySH) and thiourea (TU), and have characterized the adducts and reaction pathways. NADA and NBAD react similarly, but their adducts with NACySH and TU were formed regioselectively. NACySH yields mainly 5-adducts and TU only 6-adducts. The NACySH adducts are oxidized more easily than the parent N-acyldopamine, and their oxidations are chemically reversible. However, the TU adducts are more difficult to oxidize, and their oxidation products undergo further chemical reactions. An intramolecular base catalysis mechanism for adduct formation with NACySH is proposed, which facilitates removal of the proton from the sulfhydryl group of NACySH and directs formation of the 5-adduct via a 1,6-Michael addition reaction. The absence of a proton on the thioureylene sulfur atom leads to formation of the 6-thioureylene adduct via a 1,4-Michael addition reaction of TU. This mechanism is consistent with the formation of other sulfur-centered adducts of catechols previously reported in the literature.
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Affiliation(s)
- X Huang
- Agricultural Research Service, Kansas State University, Manhattan, Kansas 66506, USA
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Memoli S, Napolitano A, d'Ischia M, Misuraca G, Palumbo A, Prota G. Diffusible melanin-related metabolites are potent inhibitors of lipid peroxidation. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1346:61-8. [PMID: 9187303 DOI: 10.1016/s0005-2760(97)00018-0] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Although it has long been known that epidermal melanocytes produce and excrete a number of melanin-related metabolites, including 5.6-dihydroxyindole (DHI), 5,6-dihydroxyindole-2-carboxylic acid (DHICA), and 5-S-cysteinyldopa (CD), the possible functional significance of these compounds has been so far largely overlooked. We report now evidence that DHI, DHICA and CD exert potent inhibitory effects in different in vitro models of lipid peroxidation. The compounds, at 100 microM concentration, substantially decreased malondialdehyde (MDA) formation by lipid peroxidation in rat brain cortex homogenates. At 1.2 microM concentration, DHI proved as effective as alpha-tocopherol (alpha-T), one of the most potent endogenous antioxidants, in suppressing azo-induced peroxidation of linoleic acid in phosphate buffer (pH 7.4), containing 0.10 M SDS, whereas CD and DHICA at the same concentration were less active. DHI, CD and DHICA (all in the range 25 microM-0.5 mM) were also found to inhibit Fe (II)/EDTA-induced oxidation of 0.5 mM arachidonic acid at pH 7.4, as well as MDA formation by iron-promoted degradation of 0.5 mM 15-hydroperoxy-5,8,11, 13-eicosatetraenoic acid (15-HPETE). In both cases the inhibitory effects were much greater than those of ascorbic acid and glutathione. These results point to melanin precursors as a novel class of biological antioxidants which may contribute to defense mechanisms against oxidative injury in human skin.
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Affiliation(s)
- S Memoli
- Department of Organic and Biological Chemistry, University of Naples Federico II, Italy
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Abstract
Over the past few years, pigment cell research has experienced unprecedented impetus in practically all areas. However, as is usually the case in periods of rapid development, several critical issues buried under the glitz of recent success are more or less the same as they have been for many years. Persisting misconceptions and scientific prejudices also contribute to cloud many issues. It appears, for example, that the common perception of melanocyte function is still biased by the traditional concept of a pigment producing cell. In fact, in addition to melanin, epidermal melanocytes are known to produce and excrete a number of melanin-related metabolites, such as DHI and DHICA, which appear to play a critical role in protection of epidermal tissues against toxic oxygen radical species as well as in inflammatory and immune reactions. Another major gap concerns the pheomelanin pigmentary system. This has traditionally been a neglected area of research in spite of compelling evidence for the abnormal susceptibility of red heads to sun damage and skin cancer. An increased attention to the peculiar biological and biochemical features of the pheomelanin forming cells will expectedly open new vistas on the UV susceptibility trait and the etiology of melanoma.
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Affiliation(s)
- G Prota
- Department of Organic and Biological Chemistry, University of Naples Federico II, Italy
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