Electrochemical aspects of the reduction of biologically active 2-hydroxy-3-alkyl-1,4-naphthoquinones

Ferraz, Patrícia A. L.; Abreu, Fabiane Caxico de; Pinto, Antônio V.; Glezer, Victor; Tonholo, Josealdo; Goulart, Marília Oliveira Fonseca

doi:10.1016/s0022-0728(01)00439-9

Cited by 87 publications

(73 citation statements)

References 26 publications

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“…The band located at 3351 cm −1 in the free lapachol [31,32] assigned to OH, disappears upon coordination, as expected. The characteristic ν(C_O) stretching bands, found at ν(C 1 _O) 1664 and ν(C 4 _O) 1641 cm −1 in free lapachol [11] shifted to lower frequencies in complexes, 1561-1591 cm −1 and 1581-1533 cm −1 , respectively.…”

Section: Fragmentsupporting

confidence: 80%

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Antiparasitic activities of novel ruthenium/lapachol complexes

Barbosa

Corrêa

Oliveira

et al. 2014

Journal of Inorganic Biochemistry

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The present study describes the synthesis, characterization, antileishmanial and antiplasmodial activities of novel diimine/(2,2′-bipyridine (bipy), 1,10-phenanthroline (phen), 4,4′-methylbipyridine (Me-bipy) and 4,4′-methoxybipyridine (MeO-bipy)/phosphine/ruthenium(II) complexes containing lapachol (Lap, 2-hydroxy-3- The Ru(III) complex, [RuCl 2 (Lap)(dppb)], was also characterized by the EPR technique. The structure of the complexes [Ru(Lap)(PPh 3 ) 2 (bipy)]PF 6 and [RuCl 2 (Lap)(dppb)] was elucidated by X-ray diffraction. The evaluation of the antiparasitic activities of the complexes against Leishmania amazonensis and Plasmodium falciparum demonstrated that lapachol-ruthenium complexes are more potent than the free lapachol. The [RuCl 2 (Lap)(dppb)] complex is the most potent and selective antiparasitic compound among the five new ruthenium complexes studied in this work, exhibiting an activity comparable to the reference drugs.

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Section: Fragmentsupporting

confidence: 80%

“…3 for the case of complex (4). In the negative region a quasi-reversible oneelectron reduction process was observed in all cases, which most probably correspond to the ligand reduction to the semiquinone form [31]. As can be seen in Table 3 the redox potential of 1-4 decreases when the diimine basicity is increased.…”

Section: Fragmentmentioning

confidence: 71%

Antiparasitic activities of novel ruthenium/lapachol complexes

Barbosa

Corrêa

Oliveira

et al. 2014

Journal of Inorganic Biochemistry

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“…The same result was obtained with oncocalyxone A. Reductive acetylation, as earlier reported, 20,34 was performed with consumption of 2 mol electron mol -1 and led to the corresponding acetylated hydroquinone (Figure 1c) (see Experimental section).…”

Section: Electrochemical Experiments In Aprotic Mediumsupporting

confidence: 84%

Oncocalyxone A: electrochemical, spectroscopic investigation and studies of its interaction with DNA, nucleobases and N-acetylcysteine

Costa¹,

Costa²,

Ferreira³

et al. 2012

J. Braz. Chem. Soc.

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A formação de espécies paramagnéticas a partir da oncocalixona A em meio aprótico foi confirmada pela realização de experimentos eletroquímicos in situ em conjunto com ressonância de spin eletrônico (E-ESR). A alta deslocalização do radical gerado no primeiro potencial de redução está claramente evidenciada pelo acoplamento hiperfino do H-9 com a maior constante de acoplamento, além dos acoplamentos nas posições H-3 (próximo à quinona) e H-7 (distante do núcleo quinônico). Em meio prótico, além dos experimentos de dependência com o pH, oncocalixona A mostrou-se DNA-reativa por meio de experimentos eletroquímicos com sensores de DNA. Sua reação com N-acetilcisteína, com caracterização estrutural dos produtos de adição, evidencia sua habilidade como aceptor de Michael. Ambos os aspectos são importantes em termos de atividades biológicas/farmacológicas e indicam os presentes modelos como ferramentas importantes na avaliação de compostos biologicamente ativos.The formation of paramagnetic species from oncocalyxone A in aprotic medium was confirmed by performing in situ electrochemical-electron spin resonance (E-ESR) experiments. The high delocalization of the radical generated at the first reduction potential is clearly evidenced by the hyperfine coupling of H-9 with the larger coupling constant, besides the couplings at the H-3 (close to quinone) and H-7 (far from the quinone nucleus) positions. In protic medium, together with pH dependence experiments, oncocalyxone A showed to be DNA-reactive through experiments with DNA sensors. Its reaction with N-acetylcysteine, with structural characterization of the addition products, proved its ability as Michael acceptor. Both aspects are important in terms of biological/ pharmacological activities and indicate the present models as important tools in the screening of biologically active compounds.Keywords: oncocalyxone A, spectroelectrochemical-electron spin resonance, DNA interaction, N-acetylcysteine, Michael acceptor IntroductionOncocalyxone A (rel-8α-hydroxy-5-hydroxymethyl-2 -m e t h o x y -8 a , β -m e t h y l -7 , 8 , 8 a , 9 -t e t r a h y d r o -1,4-anthracenedione) ( Figure 1a) is a natural parabenzoquinone isolated from Auxemma oncocalyx TAUB, popularly known as "pau branco", that belongs to the Boraginaceae family. 1,2 Oncocalyxone A exhibits a series of biological properties, 2 such as cytotoxic, analgesic and anti-inflammatory, it causes DNA damage and inhibition Costa et al. 1175 Vol. 23, No. 6, 2012 of platelet activation. 3,4,[5][6][7][8] Oncocalyxone A also shows differential antitumor activity against the murine tumors Ehrlich carcinoma, sarcoma 180 and L1210 leukemia. 8 In general, two major mechanisms of quinone cytotoxicity have been proposed: stimulation of oxidative stress and alkylation of cellular nucleophiles, which encompass large range of biomolecules, 9 such as DNA and some enzymes, e.g., topoisomerase and protein tyrosine phosphatases, mainly those with thiol groups. 10 Oncocalyxone A, a para-benzoquinone with an extended conjugated dienon...

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“…The electrochemical behavior of different classes of quinones has been extensively reviewed [33]. In the specific case of hydroxyquinones, the possibility of stabilization of the electrogenerated anion radical by intramolecular hydrogen bonding causes a shift of the reduction potentials to less negative values [34,35] a fact that in some cases can be fundamental with respect to biological activity [35].…”

Section: Discussionmentioning

confidence: 99%

“…Such behavior could be explained considering that the carboxylate is a long chain directly bounded to the furan ring and cause a positive electronic effect. Furthermore, the decrease in activity observed for the 1a and 3b derivatives may be related to the presence of the hydrophilic isoquinoline substituent, since excess of hydrophobicity causes loss of activity [33].…”

Section: Discussionmentioning

confidence: 99%

Antimicrobial Activities of the Henna Extract and Some Synthetic Naphthoquinones Derivatives

Rahmoun¹,

Boucherit-Atmani²,

Benabdallah³

et al. 2013

AJMBR

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Naphthoquinones are compounds widely distributed in the environment, both as natural products and as pharmaceutical agents. They have been the subject of much research due to their pharmacological activities. In this study, methanol extract of henna and a series of synthesized structural analogue of lawsone have been assessed for their antimicrobial activities. Methanol extract of henna and eight naphthoquinones derivatives were tested as potential antimicrobial agents against twelve bacteria and three Candida species using the agar disc diffusion and broth microdilution methods according to guidelines recommended by the Clinical and Laboratory Standards Institute. Besides 2b and 3b, methanol extract and all the synthesized compounds 1a, 2a, 1b and 1c, 2c and 3c showed weakto-strong activity against at least one tested strain. However, the compounds 1c and 1b were found to have the most effective activity against pathogenic bacteria and displayed an activity 8 to 64 fold higher than that othe structural analogue, lawsone. Their MICs ranged from 8-64 µg ml -1. Henna extract was found to have an interesting activity. Our results indicate an effective in vitro activity of 1,4-naphthoquinone derivatives and suggest the benefits of further studies for its application in antibiotherapy.

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Electrochemical aspects of the reduction of biologically active 2-hydroxy-3-alkyl-1,4-naphthoquinones

Cited by 87 publications

References 26 publications

Antiparasitic activities of novel ruthenium/lapachol complexes

Antiparasitic activities of novel ruthenium/lapachol complexes

Oncocalyxone A: electrochemical, spectroscopic investigation and studies of its interaction with DNA, nucleobases and N-acetylcysteine

Antimicrobial Activities of the Henna Extract and Some Synthetic Naphthoquinones Derivatives

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