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Lewtak JP, Landman M, Fernández I, Swarts JC. A DFT-Elucidated Comparison of the Solution-Phase and SAM Electrochemical Properties of Short-Chain Mercaptoalkylferrocenes: Synthetic and Spectroscopic Aspects, and the Structure of Fc-CH2CH2-S-S-CH2CH2-Fc. Inorg Chem 2016; 55:2584-96. [PMID: 26901655 DOI: 10.1021/acs.inorgchem.5b02936] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Facile synthetic procedures to synthesize a series of difficult-to-obtain mercaptoalkylferrocenes, namely, Fc(CH2)nSH, where n = 1 (1), 2 (2), 3 (3), or 4 (4) and Fc = Fe(η(5)-C5H5)(η(5)-C5H4), are reported. Dimerization of 1-4 to the corresponding disulfides 19-22 was observed in air. Dimer 20 (Z = 2) crystallized in the triclinic space group P1̅. Dimers 20-22 could be reduced back to the original Fc(CH2)nSH derivatives with LiAlH4 in refluxing tetrahydrofuran. Density functional theory (DFT) calculations showed that the highest occupied molecular orbital of 1-4 lies exclusively on the ferrocenyl group implying that the electrochemical oxidation observed at ca. -15 < Epa < 76 mV versus FcH/FcH(+) involves exclusively an Fe(II) to Fe(III) process. Further DFT calculations showed this one-electron oxidation is followed by proton loss on the thiol group to generate a radical, Fc(CH2)nS(•), with spin density mainly located on the sulfur. Rapid exothermic dimerization leads to the observed dimers, Fc(CH2)n-S-S-(CH 2)nFc. Reduction of the ferrocenium groups on the dimer occurs at potentials that still showed the ferrocenyl group ΔE = Epa,monomer - Epc,dimer ≤ 78 mV, indicating that the redox properties of the ferrocenyl group on the mercaptans are very similar to those of the dimer. (1)H NMR measurements showed that, like ferrocenyl oxidation, the resonance position of the sulfhydryl proton, SH, and others, are dependent on -(CH2)n- chain length. Self-assembled monolayers (SAMs) on gold were generated to investigate the electrochemical behavior of 1-4 in the absence of diffusion. Under these conditions, ΔE approached 0 mV for the longer chain derivatives at slow scan rates. The surface-bound ferrocenyl group of the metal-thioether, Fc(CH2)n -S-Au, is oxidized at approximately equal potentials as the equivalent CH2Cl2-dissolved ferrocenyl species 1-4. Surface coverage by the SAMs is dependent on alkyl chain length with the largest coverage obtained for 4, while the rate of heterogeneous electron transfer between SAM substrate and electrode was the fastest for the shortest chain derivative, Fc-CH2-S-Au.
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Affiliation(s)
- Jan P Lewtak
- Department of Chemistry, University of the Free State , P.O. Box 339, Bloemfontein 9300, Republic of South Africa
| | - Marilé Landman
- Department of Chemistry, University of Pretoria , Private Bag X20, Hatfield 0028, Republic of South Africa
| | - Israel Fernández
- Departamento de Química Orgánica I, Facultad de Ciencias Químicas, Universidad Complutense de Madrid , 28040 Madrid, Spain
| | - Jannie C Swarts
- Department of Chemistry, University of the Free State , P.O. Box 339, Bloemfontein 9300, Republic of South Africa
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Kostova MB, Myers CJ, Beck TN, Plotkin BJ, Green JM, Boshoff HI, Barry CE, Deschamps JR, Konaklieva MI. C4-alkylthiols with activity against Moraxella catarrhalis and Mycobacterium tuberculosis. Bioorg Med Chem 2011; 19:6842-52. [PMID: 22014754 PMCID: PMC3701103 DOI: 10.1016/j.bmc.2011.09.030] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Revised: 09/11/2011] [Accepted: 09/19/2011] [Indexed: 10/17/2022]
Abstract
Antimicrobial resistance represents a global threat to healthcare. The ability to adequately treat infectious diseases is increasingly under siege due to the emergence of drug-resistant microorganisms. New approaches to drug development are especially needed to target organisms that exhibit broad antibiotic resistance due to expression of β-lactamases which is the most common mechanism by which bacteria become resistant to β-lactam antibiotics. We designed and synthesized 20 novel monocyclic β-lactams with alkyl- and aryl-thio moieties at C4, and subsequently tested these for antibacterial activity. These compounds demonstrated intrinsic activity against serine β-lactamase producing Mycobacterium tuberculosis wild type strain (Mtb) and multiple (n=6) β-lactamase producing Moraxella catarrhalis clinical isolates.
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Affiliation(s)
- Maya B. Kostova
- Department of Chemistry, American University, Washington, DC 20016, USA
| | - Carey J. Myers
- Department of Chemistry, American University, Washington, DC 20016, USA
| | - Tim N. Beck
- Department of Chemistry, American University, Washington, DC 20016, USA
| | - Balbina J. Plotkin
- Department of Microbiology and Immunology, Midwestern University, Downers Grove, IL 60515, USA
| | - Jacalyn M. Green
- Department of Biochemistry, Midwestern University, Downers Grove, IL 60515, USA
| | - Helena I.M. Boshoff
- Tuberculosis Research Section, LCID, NIAID, NIH, 33 North Drive, Bldg 33, Rm 2W20C, Bethesda, MD 20892, USA
| | - Clifton E. Barry
- Tuberculosis Research Section, LCID, NIAID, NIH, 33 North Drive, Bldg 33, Rm 2W20C, Bethesda, MD 20892, USA
| | - Jeffrey R. Deschamps
- Naval Research Laboratory, Code 6930, 4555 Overlook Ave., Washington, DC 20375, USA
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Folsom JP, Baker B, Stewart PS. In vitro efficacy of bismuth thiols against biofilms formed by bacteria isolated from human chronic wounds. J Appl Microbiol 2011; 111:989-96. [PMID: 21794034 DOI: 10.1111/j.1365-2672.2011.05110.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
AIMS The purpose of this study was to evaluate the antimicrobial efficacy of thirteen bismuth thiol preparations for bactericidal activity against established biofilms formed by two bacteria isolated from human chronic wounds. METHODS Single species biofilms of a Pseudomonas aeruginosa or a methicillin-resistant Staphylococcus aureus were grown in either colony biofilm or drip-flow reactors systems. Biofilms were challenged with bismuth thiols, antibiotics or silver sulfadiazine, and log reductions were determined by plating for colony formation. CONCLUSIONS Antibiotics were ineffective or inconsistent against biofilms of both bacterial species tested. None of the antibiotics tested were able to achieve >2 log reductions in both biofilm models. The 13 different bismuth thiols tested in this investigation achieved widely varying degrees of killing, even against the same micro-organism in the same biofilm model. For each micro-organism, the best bismuth thiol easily outperformed the best conventional antibiotic. Against P. aeruginosa biofilms, bismuth-2,3-dimercaptopropanol (BisBAL) at 40-80 μg ml⁻¹ achieved > 7·7 mean log reduction for the two biofilm models. Against MRSA biofilms, bismuth-1,3-propanedithiol/bismuth-2-mercaptopyridine N-oxide (BisBDT/PYR) achieved a 4·9 log reduction. SIGNIFICANCE AND IMPACT OF THE STUDY Bismuth thiols are effective antimicrobial agents against biofilms formed by wound bacteria and merit further development as topical antiseptics for the suppression of biofilms in chronic wounds.
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Affiliation(s)
- J P Folsom
- Center for Biofilm Engineering, Montana State University, Bozeman, MT, USA Microbion Corporation, Bozeman, MT, USA
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Badireddy A, Chellam S. Bismuth dimercaptopropanol (BisBAL) inhibits formation of multispecies wastewater flocs. J Appl Microbiol 2011; 110:1426-37. [DOI: 10.1111/j.1365-2672.2011.05002.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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Pérez LM, Alvarez BL, Codony F, Fittipaldi M, Adrados B, Peñuela G, Morató J. A new microtitre plate screening method for evaluating the viability of aerobic respiring bacteria in high surface biofilms. Lett Appl Microbiol 2010; 51:331-7. [PMID: 20681967 DOI: 10.1111/j.1472-765x.2010.02902.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
AIMS It is difficult to determine the effects of bactericidal compounds against bacteria in a biofilm because classical procedures for determining cell viability require several working days, multiple complicated steps and are frequently only applicable to cells in suspension. We attempt to develop a compact, inexpensive and versatile system to measure directly the extent of biofilm formation from water systems and to determine the viability of respiring bacteria in high surface biofilms. METHODS AND RESULTS It has been reported that the reduction of tetrazolium sodium salts, such as XTT (sodium 3,3'-[1-[(phenylamino)carbonyl]-3,4-tetrazolium]Bis(4-methoxy)-6-nitro)benzene sulfonic acid hydrate), during active bacterial metabolism can be incorporated into a colorimetric method for quantifying cell viability. XTT is reduced to a soluble formazan compound during bacterial aerobic metabolism such that the amount of formazan generated is proportional to the bacterial biomass. CONCLUSIONS We show here, for the first time, that this colorimetric approach can be used to determine the metabolic activity of adherent aerobic bacteria in a biofilm as a measure of cell viability. This technique has been used to estimate viability and proliferation of bacteria in suspension, but this is the first application to microbial communities in a real undisturbed biofilm. SIGNIFICANCE AND IMPACT OF THE STUDY This simple new system can be used to evaluate the complex biofilm community without separating the bacteria from their support. Thus, the results obtained by this practice may be more representative of the circumstances in a natural system, opening the possibility to multiple potential applications.
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Affiliation(s)
- L M Pérez
- Laboratori de Microbiologia Sanitaria i Mediambiental (MSM-Lab) & Aquasost - UNESCO Chair in Sustainability, Universitat Politècnica de Catalunya (UPC), Terrassa, Barcelona, Spain
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Hashmi I, Farooq S, Qaiser S. Chlorination and water quality monitoring within a public drinking water supply in Rawalpindi Cantt (Westridge and Tench) area, Pakistan. ENVIRONMENTAL MONITORING AND ASSESSMENT 2009; 158:393-403. [PMID: 18972214 DOI: 10.1007/s10661-008-0592-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2008] [Accepted: 09/29/2008] [Indexed: 05/27/2023]
Abstract
Concern over the presence of fecal coliform in public drinking water supplies has been expressed in recent years in Pakistan since it has been regarded as pathogenic organism of prime importance in gastroenteritis. Two major drinking water distribution systems in the Cantt area of Rawalpindi district covering the Westridge and Tench areas was monitored over a 2-month period to determine the prevalence of fecal coliform and chlorine residual. The collected samples were examined for total chlorine, free chlorine residual, chloramines, total coliforms, fecal coliforms, and turbidity. The drinking water quality monitoring in the distribution network was performed by collecting samples from water source, overhead reservoir, and residential taps. In the Westridge area, total chlorine varied from the lowest value of 0.27 mg/L at Station # W-5 to the highest value of 0.42 mg/L at Station # W-2, total coliforms varied from 1.1 to 3.6 most probable number (MPN)/100 mL with presence of Escherichia coli in all samples, total dissolved solids (TDS) ranged from 199.5 to 205 mg/L, conductivity fluctuated between 399 and 411 microS/cm, and turbidity varied from 0.43 to 0.73 NTU. In the Tench area, the value of total chlorine ranged from 0.14 mg/L at Station # T-7 to 0.55 mg/L at Station # T-1. Total coliform varied from 3.6 to 5.1 MPN/100 mL and fecal coliform were detected at all the stations except at Station # T-1. TDS ranged from 201.4 to 257 mg/L, conductivity varied from 343 to 513 microS/cm, and turbidity ranged between 0.66 and 1.55 NTU. It is recommended to the respective agencies to ensure that the chlorine residual is available at consumer end.
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Affiliation(s)
- Imran Hashmi
- Institute of Environmental Sciences and Engineering, National University of Sciences and Technology, Tamiz-Ud-Din Road, Rawalpindi, Pakistan.
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Orta De Velásquez MT, Yáñez-Noguez I, Jiménez-Cisneros B, Luna Pabello VM. Adding silver and copper to hydrogen peroxide and peracetic acid in the disinfection of an advanced primary treatment effluent. ENVIRONMENTAL TECHNOLOGY 2008; 29:1209-17. [PMID: 18975853 DOI: 10.1080/09593330802270632] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
This paper evaluates the efficacy of hydrogen peroxide (HP) and peracetic acid (PAA) in the disinfection of an Advanced Primary Treatment (APT) effluent, and how said disinfection capacities can be enhanced by combining the oxidants with copper (Cu2+) and silver (Ag). The treatment sequence consisted of APT (adding chemicals to water to remove suspended solids by coagulation and flocculation), followed by disinfection with various doses of HP, HP+Cu2+, HP+Ag, PAA and PAA+Ag. Microbiological quality was determined by monitoring concentrations of fecal coliforms (FC), pathogenic bacteria (PB) and helminth eggs (HE) throughout the sequence. The results revealed that APT effluent still contains very high levels of bacteria as the treatment only removes 1-2 log of FC and PB, but the reduction in the number of viable helminth eggs was 83%. Subsequent disinfection stages demonstrated that both HP+Cu2+ and HP+Ag have a marked disinfection capacity for bacteria (3.9 and 3.4 log-inactivation, respectively). Peracetic acid on its own was already extremely efficient at disinfecting for bacteria, and the effect was enhanced when combining PAA with silver (PAA+Ag). The best result for HE removal was achieved by combining PAA with silver (PAA+Ag) at doses of 20 + 2.0 mg l(-1), respectively. The study concluded that the PAA+Ag and HP+Ag combinations were good alternatives for APT effluent disinfection, because the disinfected effluents met the standards in NOM-001-SEMARNAT-1996, Mexico's regulation governing the microbiological quality required in treated wastewater destined for unrestricted reuse in agricultural irrigation (< or =1 helminths per litre). Combining either of these disinfection treatments with a primary method such as APT, therefore, offers an effective and practical way of reducing the health risks normally associated with the reuse of wastewaters.
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Affiliation(s)
- M T Orta De Velásquez
- Instituto de Ingeniería, Universidad Nacional Autónoma de México, Ap. 70-472, Coyoacán, C.P. 04510, DF Mexico.
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Use of biosensor and impedance spectroscopy assays to investigate the influence of temperature on E. coli sensitivity to 3,5-dichlorophenol. Electrochim Acta 2006. [DOI: 10.1016/j.electacta.2006.03.059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Abstract
This study compared bacterial biofilm and planktonic cell susceptibility to metal toxicity by evaluating the minimum inhibitory concentration (MIC), the planktonic minimum bactericidal concentration (MBC), and minimum biofilm eradication concentration (MBEC) using the MBEC device. In total, 17 metal cations and oxyanions, chosen to represent groups VIB to VIA of the periodic table, were each tested on biofilm and planktonic cultures of Escherichia coli JM109, Staphylococcus aureus ATCC 29213, and Pseudomonas aeruginosa ATCC 27853. In contrast to control antibiotic assays, where biofilm cultures were 2 to 64 times less susceptible to killing than logarithmically growing planktonic bacteria, metal compounds killed planktonic and biofilm cultures at the same concentration in the vast majority of combinations. Our data indicate that, under the conditions reported, growth in a biofilm does not provide resistance to bacteria against killing by metal cations or oxyanions.
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Affiliation(s)
- Joe J Harrison
- Biological Sciences, University of Calgary, Calgary, Alberta, Canada T2N 1N4
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