- Synthesis and SAR of 2,3-Dihydro-1-benzofuran-4-carboxylates: Potent Salicylic Acid-Based Lead Structures against Plant Stress
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New 2,3-dihydro-1-benzofuran-4-carboxylic acid derivatives have been identified as potent lead structures against drought and cold stress in crops starting from the synthetic exploration of stabilized analogs of the natural product lunularic acid. An optimized Lewis-acid mediated cyclization gave a short and efficient access to the envisaged 2,3-dihydro-1-benzofuran-4-carboxylates. Enantioselective approaches were investigated to assess the potential impact of the chiral center on in vivo activity. Whilst 2,3-dihydro-1-benzofuran-4-carboxamides and 2,3-dihydro-1-benzofuran-4-carboxylates carrying phenyl substituents with electron-withdrawing groups exhibited only low to moderate in vivo activity, the corresponding 2,3-dihydro-1-benzofuran-4-carboxylates carrying optimized electron-donating substituents in the phenyl moiety revealed strong in vivo activity, both against drought stress in several broad-acre crops, as well as against cold stress in corn. Remarkably, several 2,3-dihydro-1-benzofuran-4-carboxylates showed stronger efficacy than the internal standards used in our in vivo SAR study.
- Bojack, Guido,Brown, Ronald W.,Dittgen, Jan,Heinemann, Ines,Helmke, Hendrik,Hills, Martin J.,Hohmann, Sabine,Holstein, Philipp M.,Schmutzler, Dirk,Frackenpohl, Jens
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- 4-Amino-1,2,4-triazole-3-thione-derived Schiff bases as metallo-β-lactamase inhibitors
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Resistance to β-lactam antibiotics in Gram-negatives producing metallo-β-lactamases (MBLs) represents a major medical threat and there is an extremely urgent need to develop clinically useful inhibitors. We previously reported the original binding mode of 5-substituted-4-amino/H-1,2,4-triazole-3-thione compounds in the catalytic site of an MBL. Moreover, we showed that, although moderately potent, they represented a promising basis for the development of broad-spectrum MBL inhibitors. Here, we synthesized and characterized a large number of 4-amino-1,2,4-triazole-3-thione-derived Schiff bases. Compared to the previous series, the presence of an aryl moiety at position 4 afforded an average 10-fold increase in potency. Among 90 synthetic compounds, more than half inhibited at least one of the six tested MBLs (L1, VIM-4, VIM-2, NDM-1, IMP-1, CphA) with Ki values in the μM to sub-μM range. Several were broad-spectrum inhibitors, also inhibiting the most clinically relevant VIM-2 and NDM-1. Active compounds generally contained halogenated, bicyclic aryl or phenolic moieties at position 5, and one substituent among o-benzoic, 2,4-dihydroxyphenyl, p-benzyloxyphenyl or 3-(m-benzoyl)-phenyl at position 4. The crystallographic structure of VIM-2 in complex with an inhibitor showed the expected binding between the triazole-thione moiety and the dinuclear centre and also revealed a network of interactions involving Phe61, Tyr67, Trp87 and the conserved Asn233. Microbiological analysis suggested that the potentiation activity of the compounds was limited by poor outer membrane penetration or efflux. This was supported by the ability of one compound to restore the susceptibility of an NDM-1-producing E. coli clinical strain toward several β-lactams in the presence only of a sub-inhibitory concentration of colistin, a permeabilizing agent. Finally, some compounds were tested against the structurally similar di-zinc human glyoxalase II and found weaker inhibitors of the latter enzyme, thus showing a promising selectivity towards MBLs.
- Baud, Damien,Bebrone, Carine,Becker, Katja,Benvenuti, Manuela,Cerboni, Giulia,Chelini, Giulia,Cutolo, Giuliano,De Luca, Filomena,Docquier, Jean-Denis,Feller, Georges,Fischer, Marina,Galleni, Moreno,Gavara, Laurent,Gresh, Nohad,Kwapien, Karolina,Legru, Alice,Mangani, Stefano,Mercuri, Paola,Pozzi, Cecilia,Sannio, Filomena,Sevaille, Laurent,Tanfoni, Silvia,Verdirosa, Federica,Berthomieu, Dorothée,Bestgen, Beno?t,Frère, Jean-Marie,Hernandez, Jean-Fran?ois
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supporting information
(2020/09/16)
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- Design of antibacterial agents: Alkyl dihydroxybenzoates against xanthomonas citri subsp. citri
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Xanthomonas citri subsp. citri (Xcc) causes citrus canker, affecting sweet orange-producing areas around the world. The current chemical treatment available for this disease is based on cupric compounds. For this reason, the objective of this study was to design antibacterial agents. In order to do this, we analyzed the anti-Xcc activity of 36 alkyl dihydroxybenzoates and we found 14 active compounds. Among them, three esters with the lowest minimum inhibitory concentration values were selected; compounds 4 (52 μM), 16 (80 μM) and 28 (88 μM). Our study demonstrated that alkyl dihydroxybenzoates cause a delay in the exponential phase. The permeability capacity of alkyl dihydroxybenzoates in a quarter of MIC was compared to nisin (positive control). Compound 28 was the most effective (93.8), compared to compound 16 (41.3) and compound 4 (13.9) by percentage values. Finally, all three compounds showed inhibition of FtsZ GTPase activity, and promoted changes in protofilaments, leading to depolymerization, which prevents bacterial cell division. In conclusion, heptyl dihydroxybenzoates (compounds 4, 16 and 28) are promising anti-Xcc agents which may serve as an alternative for the control of citrus canker.
- Nazaré, Ana Carolina,Polaquini, Carlos Roberto,Anselmo, Daiane Bertholin,Regasini, Luis Octavio,Cavalca, Lúcia Bonci,Ferreira, Henrique,Zielinska, Aleksandra,Scheffers, Dirk-Jan,Saiki, Marilia de Freitas Calmon,Monteiro, Diego Alves,Rahal, Paula,Gomes, Eleni
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- Unprecedented alkylation of carboxylic acids by boron trifluoride etherate
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The alkylation of carboxylic acids by an ethyl moiety of boron trifluoride etherate in the absence of ethyl alcohol from the reaction system is unexpected and novel. Both aromatic and aliphatic carboxylic acids were clearly alkylated affording good yields in short reaction times with the exception of nicotinic acid that necessitated an overnight reaction. It was noted that while ortho-substituted hydroxyl groups of carboxylic acids investigated were not affected by alkylation, those of meta- and para-substituted carboxylic acids were partially etherified. Furthermore, the alkylation reaction was found to be compatible with a range of functional groups such as halogens, amino and nitro groups except for the alkene function of undecylenic acid that underwent polymerisation with concomitant alkylation of its carboxylic acid function.
- Jumbam, Ndze D.,Maganga, Yamkela,Masamba, Wayiza,Mbunye, Nomthandazo I.,Mgoqi, Esethu,Mtwa, Sphumusa
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p. 387 - 392
(2018/09/06)
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- 1,2,4-Triazole-3-thione Compounds as Inhibitors of Dizinc Metallo-β-lactamases
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Metallo-β-lactamases (MBLs) cause resistance of Gram-negative bacteria to β-lactam antibiotics and are of serious concern, because they can inactivate the last-resort carbapenems and because MBL inhibitors of clinical value are still lacking. We previously identified the original binding mode of 4-amino-2,4-dihydro-5-(2-methylphenyl)-3H-1,2,4-triazole-3-thione (compound IIIA) within the dizinc active site of the L1 MBL. Herein we present the crystallographic structure of a complex of L1 with the corresponding non-amino compound IIIB (1,2-dihydro-5-(2-methylphenyl)-3H-1,2,4-triazole-3-thione). Unexpectedly, the binding mode of IIIB was similar but reverse to that of IIIA. The 3 D structures suggested that the triazole–thione scaffold was suitable to bind to the catalytic site of dizinc metalloenzymes. On the basis of these results, we synthesized 54 analogues of IIIA or IIIB. Nineteen showed IC50 values in the micromolar range toward at least one of five representative MBLs (i.e., L1, VIM-4, VIM-2, NDM-1, and IMP-1). Five of these exhibited a significant inhibition of at least four enzymes, including NDM-1, VIM-2, and IMP-1. Active compounds mainly featured either halogen or bulky bicyclic aryl substituents. Finally, some compounds were also tested on several microbial dinuclear zinc-dependent hydrolases belonging to the MBL-fold superfamily (i.e., endonucleases and glyoxalase II) to explore their activity toward structurally similar but functionally distinct enzymes. Whereas the bacterial tRNases were not inhibited, the best IC50 values toward plasmodial glyoxalase II were in the 10 μm range.
- Sevaille, Laurent,Gavara, Laurent,Bebrone, Carine,De Luca, Filomena,Nauton, Lionel,Achard, Maud,Mercuri, Paola,Tanfoni, Silvia,Borgianni, Luisa,Guyon, Carole,Lonjon, Pauline,Turan-Zitouni, Gülhan,Dzieciolowski, Julia,Becker, Katja,Bénard, Lionel,Condon, Ciaran,Maillard, Ludovic,Martinez, Jean,Frère, Jean-Marie,Dideberg, Otto,Galleni, Moreno,Docquier, Jean-Denis,Hernandez, Jean-Fran?ois
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p. 972 - 985
(2017/06/27)
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- Mono-/dihydroxybenzoic acid esters and phenol pyridinium derivatives as inhibitors of the mammalian carbonic anhydrase isoforms I, II, VII, IX, XII and XIV
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Using hydroxy-/dihydroxybenzoic acids as leads, a series of methyl, ethyl and iso-propyl esters of 4-hydroxy-benzoic acid, 2,4-, 2,5-, 2,6-, 3,4-, and 3,5-dihydroxybenzoic acids and of coumaric acid, were obtained and investigated for the inhibition of six mammalian carbonic anhydrase (CA, EC 4.2.1.1) isoforms, that is, the cytosolic CA I, II and VII, and the transmembrane CA IX, XII and XIV, many of which are established drug targets. Other compounds incorporating phenol/catechol moieties were obtained from dopamine by reaction with fluorescein isothiocyanate or with 2,4,6-trisubstituted pyrylium salts. Some aminophenols were also derivatized in a similar manner, by using pyrylium salts. Many of these compounds showed increased inhibitory action compared to the lead compounds from which they were obtained, with efficacy in the submicromolar range against most investigated CA isoforms. As phenols are a class of less investigated CA inhibitors (CAIs) compared to the sulfonamides, and their mechanism of inhibition is less well understood, compounds of the type designed here may be helpful in gaining more insights into these phenomena.
- Carta, Fabrizio,Vullo, Daniela,Maresca, Alfonso,Scozzafava, Andrea,Supuran, Claudiu T.
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supporting information
p. 1564 - 1569
(2013/04/10)
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- Introducing negative charges into bis-p-phenylene crown ethers: A study of bipyridinium-based [2]pseudorotaxanes and [2]rotaxanes
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This paper describes novel host-guest systems comprising viologen cations (guests) and the derivatives of bis-para-phenylene-34-crown-10 (hosts) with anionic groups COO- or SO3-. The structure of the resulting chargecompensated host-guest complexes, their association constants and their electrochemical behaviour have been studied. In the solid state, the viologen cations thread the negatively charged crown ethers forming electroneutral zwitterion-like [2]pseudorotaxane salts; in solution this threaded geometry is preserved. The association constants of [2]pseudorotaxane salts incorporating the 1,1′-diethylviologen moiety in solution are significantly higher than those of previously reported analogues. The extrapolated association free energies in non-aqueous media exceed -40 kJ·mol-1 at 25°C. This significant increase of the interaction free energy makes these compounds stable even in aqueous solutions. The association constants of [2]pseudorotaxane salts incorporating sterically more hindered 1,1′-diethyl-3,3′-dimethylviologen moieties are significantly lower. Structurally related [2]rotaxane salts, in which the oppositely charged ionic components are mechanically interlocked, have been prepared in good yields. It has been shown that [2]rotaxane salts incorporating anti-isomers of bisfunctionalised crown ethers are cycloenantiomeric. In both [2]pseudorotaxane and [2]rotaxane salts, the electrostatic interactions between the viologen moieties and the negatively charged crown ethers lead to very significant negative shifts of viologen reduction potentials up to 450 mV. The findings of the present study are valuable for the design of nanoscale molecular electronic devices.
- Lestini, Elena,Nikitin, Kirill,Mueller-Bunz, Helge,Fitzmaurice, Donald
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p. 1095 - 1106
(2008/09/17)
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- Chemoselective esterification of phenolic acids in the presence of sodium bicarbonate in ionic liquids
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Chemoselective esterification of phenolic acids with dialkyl sulphates or alkyl halides in the presence of sodium bicarbonate in 1,3-dialkylimidazolium ionic liquids is reported in excellent yields and less reaction time as compared to organic solvents. Copyright Taylor & Francis Group, LLC.
- Ambika,Singh, Pradeep Pratap,Chauhan
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p. 928 - 936
(2008/09/17)
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- Design principles to tune the optical properties of 1,3,4-oxadiazole- containing molecules
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We have synthesized a series of oxadiazole compounds and ethynylene analogs. Our data reveal that the ring is both optically transparent in the visible range and fully conjugating while we have also discovered the presence of a non-radiative mechanism active in molecules containing common para-dialkoxy substituents adjacent to the oxadiazole ring(s). This structure leads to a greatly reduced quantum yield, in our example dropping from 95.0% to 48.0%. Through our thorough study we have revealed evidence that this is the result of a repulsive interaction between the oxadiazole and the adjacent alkoxy oxygen atom, which we believe prevents excited-state planarity. This quantum yield reduction is preventable through the design principles presented here. The Royal Society of Chemistry 2007.
- Bolton, Onas,Kim, Jinsang
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p. 1981 - 1988
(2008/02/08)
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- Inhibitors of mammalian melanocyte tyrosinase: In vitro comparisons of alkyl esters of gentisic acid with other putative inhibitors
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To discover safe and effective topical skin-lightening agents, we have evaluated alkyl esters of the natural product gentisic acid (GA), which is related to our lead compound methyl gentisate (MG), and four putative tyrosinase inhibitors, utilizing mammalian melanocyte cell cultures and cell-free extracts. Desirable characteristics include the ability to inhibit melanogenesis in cells (ic50 50 ~ 11 and 20 μg/mL, respectively). For comparison, hydroquinone (HQ), a commercial skin 'bleaching' agent, was a less effective enzyme inhibitor (ic50 ~ 72 μg/mL), and was highly cytotoxic to melanocytes in vitro at concentrations substantially lower than the ic50 for enzymatic inhibition. Kojic acid was a potent inhibitor of the mammalian enzyme (ic50 ~ 6 μg/mL), but did not reduce pigmentation in cells. Both arbutin and magnesium ascorbyl phosphate were ineffective in the cell-free and cell-based assays. MG at 100 μg/mL exhibited a minimal inhibitory effect on DHICA oxidase (TRP-1) and no effect on DOPAchrome tautomerase (TRP-2), suggesting that MG inhibits melanogenesis primarily via tyrosinase inhibition. MG and GA were non-mutagenic at the hprt locus in V79 Chinese hamster cells, whereas HQ was highly mutagenic and cytotoxic. The properties of MG in vitro, including (1) pigmentation inhibition in melanocytes, (2) tyrosinase inhibition and selectivity, (3) reduced cytotoxicity relative to HQ, and (4) lack of mutagenic potential in mammalian cells, establish MG as a superior candidate skin-lightening agent. Copyright (C) 1999 Elsevier Science Inc.
- Curto, Ernest V.,Kwong, Cecil,Hermersdoerfer, Heino,Glatt, Hansruedi,Santis, Chie,Virador, Victoria,Hearing Jr, Vincent J.,Dooley, Thomas P.
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p. 663 - 672
(2008/04/18)
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- CHEMISTRY OF 2,5-BIS(TRIMETHYLSILOXY)FURANS. I: PREPARATION AND DIELS-ALDER REACTIONS
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A number of substituted 2,5-bis(trimethylsiloxy)furans were prepared from the corresponding succinic anhydrides, and were found to be reactive dienes from the Diels-Alder reaction with electron-withdrawing dienophiles, giving p-quinones and hydroquinones.
- Brownbridge, Peter,Chan, Tak-Hang
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p. 3423 - 3426
(2007/10/02)
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