RESUMO
In the context of pandemic viruses and pathogenic bacteria, triclosan (TCS), as a typical antibacterial agent, is widely used around the world. However, the health risks from TCS increase with exposure, and it is widespread in environmental and human samples. Notably, environmental transformation and human metabolism could induce potentially undesirable risks to humans, rather than simple decontamination or detoxification. This review summarizes the environmental and human exposure to TCS covering from 2004 to 2023. Particularly, health impacts from the environmental and metabolic transformation of TCS are emphasized. Environmental transformations aimed at decontamination are recognized to form carcinogenic products such as dioxins, and ultraviolet light and excessive active chlorine can promote the formation of these dioxin congeners, potentially threatening environmental and human health. Although TCS can be rapidly metabolized for detoxification, these processes can induce the formation of lipophilic ether metabolic analogs via cytochrome P450 catalysis, causing possible adverse cross-talk reactions in human metabolic disorders. Accordingly, TCS may be more harmful in environmental transformation and human metabolism. In particular, TCS can stimulate the transmission of antibiotic resistance even at trace levels, threatening public health. Considering these accruing epidemiological and toxicological studies indicating the multiple adverse health outcomes of TCS, we call on environmental toxicologists to pay more attention to the toxicity evolution of TCS during environmental transformation and human metabolism.
Assuntos
Triclosan , Triclosan/metabolismo , Triclosan/toxicidade , Humanos , Exposição Ambiental , Poluentes Ambientais/metabolismo , Poluentes Ambientais/toxicidade , Anti-Infecciosos Locais/metabolismo , Anti-Infecciosos Locais/toxicidade , PandemiasRESUMO
In secondary active transporters, a relatively limited set of protein folds have evolved diverse solute transport functions. Because of the conformational changes inherent to transport, altering substrate specificity typically involves remodeling the entire structural landscape, limiting our understanding of how novel substrate specificities evolve. In the current work, we examine a structurally minimalist family of model transport proteins, the small multidrug resistance (SMR) transporters, to understand the molecular basis for the emergence of a novel substrate specificity. We engineer a selective SMR protein to promiscuously export quaternary ammonium antiseptics, similar to the activity of a clade of multidrug exporters in this family. Using combinatorial mutagenesis and deep sequencing, we identify the necessary and sufficient molecular determinants of this engineered activity. Using X-ray crystallography, solid-supported membrane electrophysiology, binding assays, and a proteoliposome-based quaternary ammonium antiseptic transport assay that we developed, we dissect the mechanistic contributions of these residues to substrate polyspecificity. We find that substrate preference changes not through modification of the residues that directly interact with the substrate but through mutations peripheral to the binding pocket. Our work provides molecular insight into substrate promiscuity among the SMRs and can be applied to understand multidrug export and the evolution of novel transport functions more generally.
Assuntos
Compostos de Amônio Quaternário , Especificidade por Substrato , Compostos de Amônio Quaternário/metabolismo , Compostos de Amônio Quaternário/química , Cristalografia por Raios X , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/química , Transporte Biológico , Proteínas de Membrana Transportadoras/metabolismo , Proteínas de Membrana Transportadoras/química , Proteínas de Membrana Transportadoras/genética , Farmacorresistência Bacteriana Múltipla/genética , Anti-Infecciosos Locais/metabolismo , Anti-Infecciosos Locais/farmacologia , Anti-Infecciosos Locais/química , Modelos MolecularesRESUMO
BACKGROUND: Chlorhexidine gluconate (CHG) is a topical antiseptic solution recommended for skin preparation before central venous catheter placement and maintenance in adults and children. Although CHG is not recommended for use in children aged <2 months owing to limited safety data, it is commonly used in neonatal intensive care units worldwide. We used zebrafish model to verify the effects of early-life exposure to CHG on the developing nervous system, highlighting its impact on oligodendrocyte development and myelination. METHODS: Zebrafish embryos were exposed to different concentrations of CHG from 4 h post fertilization to examine developmental toxicity. The hatching rate, mortality, and malformation of the embryos/larvae were monitored. Oligodendrocyte lineage in transgenic zebrafish embryos was used to investigate defects in oligodendrocytes and myelin. Myelin structure, locomotor behavior, and expression levels of genes involved in myelination were investigated. RESULTS: Exposure to CHG significantly induced oligodendrocyte defects in the central nervous system, delayed myelination, and locomotor alterations. Ultra-microstructural changes with splitting and fluid-accumulated vacuoles between the myelin sheaths were found. Embryonic exposure to CHG decreased myelination, in association with downregulated mbpa, plp1b, and scrt2 gene expression. CONCLUSION: Our results suggest that CHG has a potential for myelin toxicity in the developing brain. IMPACT: To date, the neurodevelopmental toxicity of chlorhexidine gluconate (CHG) exposure on the developing brains of infants remains unknown. We demonstrated that CHG exposure to zebrafish larvae resulted in significant defects in oligodendrocytes and myelin sheaths. These CHG-exposed zebrafish larvae exhibited structural changes and locomotor alterations. Given the increased CHG use in neonates, this study is the first to identify the risk of early-life CHG exposure on the developing nervous system.
Assuntos
Anti-Infecciosos Locais , Clorexidina , Animais , Clorexidina/toxicidade , Clorexidina/metabolismo , Peixe-Zebra , Bainha de Mielina/metabolismo , Anti-Infecciosos Locais/metabolismoRESUMO
Emerging research supports that triclosan (TCS), an antimicrobial agent found in thousands of consumer products, exacerbates colitis and colitis-associated colorectal tumorigenesis in animal models. While the intestinal toxicities of TCS require the presence of gut microbiota, the molecular mechanisms involved have not been defined. Here we show that intestinal commensal microbes mediate metabolic activation of TCS in the colon and drive its gut toxicology. Using a range of in vitro, ex vivo, and in vivo approaches, we identify specific microbial ß-glucuronidase (GUS) enzymes involved and pinpoint molecular motifs required to metabolically activate TCS in the gut. Finally, we show that targeted inhibition of bacterial GUS enzymes abolishes the colitis-promoting effects of TCS, supporting an essential role of specific microbial proteins in TCS toxicity. Together, our results define a mechanism by which intestinal microbes contribute to the metabolic activation and gut toxicity of TCS, and highlight the importance of considering the contributions of the gut microbiota in evaluating the toxic potential of environmental chemicals.
Assuntos
Proteínas de Bactérias/antagonistas & inibidores , Carcinógenos/antagonistas & inibidores , Colite/prevenção & controle , Neoplasias Colorretais/prevenção & controle , Glucuronidase/antagonistas & inibidores , Inibidores de Glicosídeo Hidrolases/farmacologia , Triclosan/antagonistas & inibidores , Animais , Anti-Infecciosos Locais/química , Anti-Infecciosos Locais/metabolismo , Anti-Infecciosos Locais/toxicidade , Anticarcinógenos/química , Anticarcinógenos/farmacologia , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Sítios de Ligação , Biotransformação , Carcinogênese/efeitos dos fármacos , Carcinogênese/metabolismo , Carcinógenos/química , Carcinógenos/metabolismo , Carcinógenos/toxicidade , Colite/induzido quimicamente , Colite/enzimologia , Colite/microbiologia , Colo/efeitos dos fármacos , Colo/microbiologia , Colo/patologia , Neoplasias Colorretais/induzido quimicamente , Neoplasias Colorretais/enzimologia , Neoplasias Colorretais/microbiologia , Microbioma Gastrointestinal/efeitos dos fármacos , Expressão Gênica , Glucuronidase/química , Glucuronidase/genética , Glucuronidase/metabolismo , Inibidores de Glicosídeo Hidrolases/química , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Modelos Moleculares , Ligação Proteica , Conformação Proteica em alfa-Hélice , Conformação Proteica em Folha beta , Domínios e Motivos de Interação entre Proteínas , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Triclosan/química , Triclosan/metabolismo , Triclosan/toxicidadeRESUMO
Antibiotic resistance is a main threat to the public health. It is established that the overuse and misuse of antibiotics are highly contributing to antibiotic resistance. However, the impact of nonantibiotic antimicrobial agents like biocides on antibiotic resistance is currently investigated and studied. Triclosan (TCS) is a broad-spectrum antibacterial agent widely used as antiseptic and disinfectant. In this study, we aimed to evaluate the effect of exposure of Proteus mirabilis clinical isolates to sublethal concentrations of TCS on their antibiotic susceptibility, membrane characteristics, efflux activity, morphology, and lipid profile. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of TCS were determined for 31 P. mirabilis clinical isolates. The tested isolates were adapted to increasing sublethal concentrations of TCS. The MICs of 16 antibiotics were determined before and after adaptation. Membrane characteristics, efflux activity, ultrastructure, and lipid profile of the tested isolates were examined before and after adaptation. Most adapted P. mirabilis isolates showed increased antibiotic resistance, lower membrane integrity, lower outer and inner membrane permeability, and higher membrane depolarization. Nonsignificant change in membrane potential and lipid profile was found in adapted cells. Various morphological changes and enhanced efflux activity was noticed after adaptation. The findings of the current study suggest that the extensive usage of TCS at sublethal concentrations could contribute to the emergence of antibiotic resistance in P. mirabilis clinical isolates. TCS could induce changes in the bacterial membrane properties and increase the efflux activity and in turn decrease its susceptibility to antibiotics which would represent a public health risk.
Assuntos
Adaptação Fisiológica , Anti-Infecciosos Locais/metabolismo , Proteus mirabilis/fisiologia , Triclosan/metabolismo , Anti-Infecciosos Locais/farmacologia , Transporte Biológico/efeitos dos fármacos , Membrana Celular/efeitos dos fármacos , Membrana Celular/metabolismo , Farmacorresistência Bacteriana , Egito , Hospitais Universitários , Humanos , Testes de Sensibilidade Microbiana , Infecções por Proteus/microbiologia , Proteus mirabilis/efeitos dos fármacos , Proteus mirabilis/isolamento & purificação , Proteus mirabilis/metabolismo , Triclosan/farmacologiaRESUMO
For more than 60 years dequalinium chloride (DQ) has been used as anti-infective drug, mainly to treat local infections. It is a standard drug to treat bacterial vaginosis and an active ingredient of sore-throat lozenges. As a lipophilic bis-quaternary ammonium molecule, the drug displays membrane effects and selectively targets mitochondria to deplete DNA and to block energy production in cells. But beyond its mitochondriotropic property, DQ can interfere with the correct functioning of diverse proteins. A dozen of DQ protein targets have been identified and their implication in the antibacterial, antiviral, antifungal, antiparasitic and anticancer properties of the drug is discussed here. The anticancer effects of DQ combine a mitochondrial action, a selective inhibition of kinases (PKC-α/ß, Cdc7/Dbf4), and a modulation of Ca2+-activated K+ channels. At the bacterial level, DQ interacts with different multidrug transporters (QacR, AcrB, EmrE) and with the transcriptional regulator RamR. Other proteins implicated in the antiviral (MPER domain of gp41 HIV-1) and antiparasitic (chitinase A from Vibrio harveyi) activities have been identified. DQ also targets α -synuclein oligomers to restrict protofibrils formation implicated in some neurodegenerative disorders. In addition, DQ is a typical bolaamphiphile molecule, well suited to form liposomes and nanoparticules useful for drug entrapment and delivery (DQAsomes and others). Altogether, the review highlights the many pharmacological properties and therapeutic benefits of this old 'multi-talented' drug, which may be exploited further. Its multiple sites of actions in cells should be kept in mind when using DQ in experimental research.
Assuntos
Anti-Infecciosos Locais/administração & dosagem , Proteínas de Ciclo Celular/antagonistas & inibidores , Dequalínio/administração & dosagem , Sistemas de Liberação de Medicamentos/métodos , Mitocôndrias/efeitos dos fármacos , Animais , Anti-Infecciosos Locais/metabolismo , Proteínas de Ciclo Celular/química , Proteínas de Ciclo Celular/metabolismo , Dequalínio/metabolismo , Humanos , Mitocôndrias/metabolismo , Micoses/tratamento farmacológico , Micoses/metabolismo , Neoplasias/tratamento farmacológico , Neoplasias/metabolismo , Estrutura Secundária de Proteína , Infecções Estreptocócicas/tratamento farmacológico , Infecções Estreptocócicas/metabolismo , Vibrioses/tratamento farmacológico , Vibrioses/metabolismoRESUMO
The present study describes the development of a chlorhexidine long-term drug delivery system using starch as a biodegradable polymer base. Three batches of thermoplastic starch films, containing starch particles/nanoparticles and chlorhexidine (CHX), were manufactured by casting. Morphological characterization showed an irregular surface with particles incorporated with chlorhexidine agglomerated in a starch matrix. Nanoindentation showed that the control film (without chlorhexidine) presented a more plastic and rigid behavior in relation to the films containing CHX. CHX was partially bounded to starch and prevented starch crystallization. Starch nanoparticles formed by precipitation were observed through transmission electron microscopy. By incorporating CHX into the solution, the nanoparticles presented different morphology, suggesting absorption of the drug. In vitro drug release was observed for 21 days by UV-vis spectrophotometry and released CHX amounted up to 19 mg/100 ml. Films presented microbiological potential for inhibiting Staphylococcus aureus growth as evaluated by the disk diffusion test in agar. It has been concluded that the developed film met the main requirements for a drug delivery system and that it is possible to be produced from a simple, cheap and reproduceable process.
Assuntos
Anti-Infecciosos Locais/química , Clorexidina/análogos & derivados , Portadores de Fármacos/química , Amido/química , Zea mays/metabolismo , Anti-Infecciosos Locais/metabolismo , Anti-Infecciosos Locais/farmacologia , Clorexidina/química , Clorexidina/metabolismo , Clorexidina/farmacologia , Testes de Sensibilidade a Antimicrobianos por Disco-Difusão , Liberação Controlada de Fármacos , Módulo de Elasticidade , Nanopartículas/química , Staphylococcus aureus/efeitos dos fármacosRESUMO
Treatment of emerging contaminants, such as antimicrobials, has become a priority topic for environmental protection. As a persistent, toxic, and bioaccumulative antimicrobial, the accumulation of triclosan (TCS) in wastewater sludge is creating a potential risk to human and ecosystem health via the agricultural use of biosolids. The impact of microwave (MW) pretreatment on TCS levels in municipal sludge is unknown. This study, for the first time, evaluated how MW pretreatment (80 and 160 °C) itself and together with anaerobic digestion (AD) under various sludge retention times (SRTs: 20, 12, and 6 days) and temperatures (35 and 55 °C) can affect the levels of TCS in municipal sludge. TCS and its potential transformation products were analyzed with ultra-high-performance liquid chromatography and tandem mass spectrometry. Significantly higher TCS concentrations were detected in sludge sampled from the plant in colder compared to those in warmer temperatures. MW temperature did not have a discernible impact on TCS reduction from undigested sludge. However, AD studies indicated that compared to controls (no pretreatment), MW irradiation could make TCS more amenable to biodegradation (up to 46%), especially at the elevated pretreatment and digester temperatures. At different SRTs studied, TCS levels in the thermophilic digesters were considerably lower than that of in the mesophilic digesters.
Assuntos
Anti-Infecciosos Locais/metabolismo , Poluentes Ambientais/metabolismo , Esgotos/química , Triclosan/metabolismo , Anaerobiose/fisiologia , Anti-Infecciosos Locais/análise , Biodegradação Ambiental , Cromatografia Líquida de Alta Pressão , Poluentes Ambientais/análise , Temperatura Alta , Humanos , Micro-Ondas , Esgotos/microbiologia , Espectrometria de Massas em Tandem , Triclosan/análise , Eliminação de Resíduos LíquidosRESUMO
Chlorhexidine (CHX) and octenidine (OCT), antimicrobial compounds used in oral care products (toothpastes and mouthwashes), were recently revealed to interfere with human sex hormone receptor pathways. Experiments employing model organisms-white-rot fungi Irpex lacteus and Pleurotus ostreatus-were carried out in order to investigate the biodegradability of these endocrine-disrupting compounds and the capability of the fungi and their extracellular enzyme apparatuses to biodegrade CHX and OCT. Up to 70% ± 6% of CHX was eliminated in comparison with a heat-killed control after 21 days of in vivo incubation. An additional in vitro experiment confirmed manganese-dependent peroxidase and laccase are partially responsible for the removal of CHX. Up to 48% ± 7% of OCT was removed in the same in vivo experiment, but the strong sorption of OCT on fungal biomass prevented a clear evaluation of the involvement of the fungi or extracellular enzymes. On the other hand, metabolites indicating the enzymatic transformation of both CHX and OCT were detected and their chemical structures were proposed by means of liquid chromatography-mass spectrometry. Complete biodegradation by the ligninolytic fungi was not achieved for any of the studied analytes, which emphasizes their recalcitrant character with low possibility to be removed from the environment.
Assuntos
Anti-Infecciosos Locais/metabolismo , Biodegradação Ambiental , Clorexidina/metabolismo , Fungos/metabolismo , Piridinas/metabolismo , Clorexidina/química , Assistência Odontológica , Humanos , Iminas , Metabolômica/métodos , Piridinas/química , Transformação GenéticaRESUMO
Triclosan (TCS) is an antibacterial and antifungal compound found in many hygiene products, including toothpaste, soap, and detergents. However, this molecule can act as an endocrine disruptor and can induce harmful effects on human health and the environment. In this study, triclosan was biotransformed in vitro using human and rat liver fractions, to evaluate oxidative metabolism, the formation of reactive metabolites via the detection of GSH adducts, as well as glucuronide and sulfate conjugates using liquid chromatography coupled to high-resolution tandem mass spectrometry (LC-HRMS/MS). A deuterated analog of triclosan was also employed for better structural elucidation of specific metabolic sites. Several GSH adducts were found, either via oxidative metabolism of triclosan or its cleavage product, 2,4-dichlorophenol. We also detected glucuronide and sulfated conjugates of triclosan and its cleaved product. This study was aimed at understanding the routes of detoxification of this xenobiotic, as well as investigating any potential pathways related to additional toxicity via reactive metabolite formation. Graphical abstract.
Assuntos
Anti-Infecciosos Locais/metabolismo , Cromatografia Líquida/métodos , Espectrometria de Massas em Tandem/métodos , Triclosan/metabolismo , Animais , Glucuronídeos/metabolismo , Glutationa/metabolismo , Humanos , Microssomos Hepáticos/metabolismo , Oxirredução , Ratos , Sulfatos/metabolismoRESUMO
PURPOSE: The association between iodine intake and thyroid autoimmunity has been debated, especially in pregnant women. This study aimed to investigate thyroid autoantibodies and their association with iodine intake and hypothyroidism in early pregnancy. METHODS: 7073 early pregnant women from an iodine-sufficient region participated in this study. Urinary iodine concentrations (UICs) were measured using an ammonium persulfate method. Serum thyroid peroxidase antibody (TPOAb), thyroglobulin antibody (TgAb), thyroid-stimulating hormone (TSH), free thyroxine (FT4), and Tg were determined using an electrochemiluminescence immunoassay. RESULTS: Iodine deficiency (UIC < 100 µg/L) was associated with higher risks of TPOAb positivity [adjusted odds ratio (aOR) = 1.64, 95% confidence interval [CI] (1.29-2.08)] and TgAb positivity [aOR = 1.44, 95% CI (1.16-1.80)]. Women with isolated TPOAb positivity, isolated TgAb positivity, or both TPOAb and TgAb positivity had a 14.64-fold, 7.83-fold, and 44.69-fold increased risk of overt hypothyroidism, and a 4.36-fold, 2.86-fold, and 6.26-fold increased risk of subclinical hypothyroidism, respectively. Moreover, the risks of overt and subclinical hypothyroidism in women with a high TPOAb titer were 16.99 and 4.80 times that in TPOAb-negative women, respectively. The risk of overt hypothyroidism in women with a high TgAb titer was 6.97 times that in TgAb-negative women. CONCLUSIONS: Our work demonstrates that iodine deficiency during early pregnancy is an independent risk factor for both TPOAb positivity and TgAb positivity. Furthermore, positivity for both autoantibodies and a high thyroid autoantibody titer are associated with significantly higher risks of overt and subclinical hypothyroidism.
Assuntos
Autoanticorpos/sangue , Biomarcadores/sangue , Hipotireoidismo/diagnóstico , Iodo/deficiência , Hormônios Tireóideos/sangue , Adulto , Anti-Infecciosos Locais/administração & dosagem , Anti-Infecciosos Locais/metabolismo , Autoanticorpos/imunologia , Estudos Transversais , Feminino , Seguimentos , Humanos , Hipotireoidismo/sangue , Hipotireoidismo/imunologia , Iodo/administração & dosagem , Gravidez , Prognóstico , Adulto JovemRESUMO
BACKGROUND: Bacterial nanocellulose (BNC) is considered a promising carrier for various substances and novel approaches using BNC in combination with antiseptics are well documented. However, the difference in the molecular weight of these molecules influences their uptake by and release from BNC. Analysing the diffusion of standard molecules with different weight, e.g. dextrans, offers the possibility to investigate the mobility of various molecules. We aimed to test the use of BNC regarding uptake and release of different standard molecules as well as two commercially available antiseptics for possible applications in future wound dressings. MATERIAL AND METHODS: Diffusion profiles, uptake and release of three FITC-dextran molecules differing in weight as well as octenidine (Octenisept®) and povidone-iodine (Betaisodona®)-based antiseptics were tested with BNC-based wound dressings. Furthermore, the antiseptic efficacy of BNC in combination with antiseptics against Staphylococcus aureus was tested. RESULTS: Uptake and release capacity for FITC-dextran molecules showed a molecular weight-dependent mobility from BNC into an agarose gel. The loading capacity of BNC was also inversely proportional to the molecular weight of the antiseptics. The release test for octenidine showed a sustained and prolonged delivery into a solid matrix, whereas povidone-iodine was released faster. Both antiseptic solutions combined with BNC showed a good dose-dependent efficacy against S. aureus. CONCLUSION: Results obtained from the mobility of FITC-dextran molecules in the BNC matrix could open possible applications for the combination of BNC with other molecules for medical applications. Combination of both tested antiseptics with BNC showed to be an efficient approach to control bacterial infections.
Assuntos
Anti-Infecciosos Locais/metabolismo , Bandagens , Queimaduras/terapia , Celulose/metabolismo , Povidona-Iodo/metabolismo , Piridinas/metabolismo , Infecção dos Ferimentos/prevenção & controle , Anti-Infecciosos Locais/administração & dosagem , Dextranos/metabolismo , Portadores de Fármacos/metabolismo , Fluoresceína-5-Isotiocianato/análogos & derivados , Fluoresceína-5-Isotiocianato/metabolismo , Humanos , Iminas , Peso Molecular , Nanoestruturas , Povidona-Iodo/administração & dosagem , Piridinas/administração & dosagem , Ferimentos e Lesões/terapiaRESUMO
BACKGROUND: Streptococcus suis is a prominent pathogen causing septicemia and meningitis in swine and humans. Bacitracin is used widely as a growth promoter in animal feed and to control the spread of necrotic enteritis in most developing countries. This study aimed to characterize a novel membrane transporter module Sst comprising SstE, SstF, and SstG for bacitracin resistance. RESULTS: Comparative genomics and protein homology analysis found a potential efflux pump SstFEG encoded upstream of well-known bacitracin-resistance genes bceAB and bceRS. A four-fold decrease in bacitracin susceptibility was observed in sstFEG deletion mutant comparing with S. suis wildtype strain CZ130302. Further studies indicated that the bacitracin tolerance mediated by SstFEG is not only independent of the BceAB transporter, but also regulated by the two-component system BceSR. Given that SstFEG are harbored by almost all virulent strains, but not in the avirulent strains, we managed to explore its potential role in bacterial pathogencity. Indeed, our results showed that SstFEG is involved in S. suis colonization and virulence in animal infection model by its potential competitive survival advantage against host bactericidal effect. CONCLUSION: To our knowledge, this is the first study to functionally characterize the bacitracin efflux pump in S. suis to provide evidence regarding the important roles of the novel ABC transporter system SstFEG with respect to drug resistance and virulence.
Assuntos
Antibacterianos/farmacologia , Bacitracina/farmacologia , Proteínas de Bactérias/metabolismo , Farmacorresistência Bacteriana , Proteínas de Membrana Transportadoras/metabolismo , Streptococcus suis/efeitos dos fármacos , Animais , Antibacterianos/metabolismo , Anti-Infecciosos Locais/metabolismo , Anti-Infecciosos Locais/farmacologia , Bacitracina/metabolismo , Proteínas de Bactérias/genética , Feminino , Deleção de Genes , Regulação Bacteriana da Expressão Gênica , Proteínas de Membrana Transportadoras/genética , Camundongos , Camundongos Endogâmicos BALB C , Testes de Sensibilidade Microbiana , Infecções Estreptocócicas/microbiologia , Streptococcus suis/metabolismo , Streptococcus suis/patogenicidade , VirulênciaRESUMO
Bacitracin is a cyclic dodecyl peptide antibiotic that is an effective bacteriocide against Gram-positive and some Gram-negative bacteria. Bacitracin has been widely used as an antibacterial feed additive for livestock since it is not absorbed easily by the intestine and is easily excreted. Precursor availability has been proven to be one of the core factors for bacitracin production by many previous studies. In this study, we focused on enhancing the supply of the precursor amino acid L-ornithine to enhance bacitracin production by Bacillus licheniformis DW2 through systematic metabolic pathway modification. Several genes encoding rate-limiting enzymes for L-ornithine biosynthesis were episomally overexpressed, including argB, rocF, ppnk1, and ppnk2. The results showed that the overexpression of ppnK1 was the most effective for both L-ornithine and bacitracin biosynthesis. Secondly, the competitive branch pathways for L-ornithine biosynthesis were blocked, and the repressor was also deleted to boost L-ornithine biosynthesis. The results suggested that the deletion of genes proB and proJ to prevent proline biosynthesis and the disruption of the gene encoding the arginine repressor ArgR could enhance the intracellular concentration of L-ornithine by 49% and 2.1 times respectively, and the bacitracin production also increased accordingly by 6.6% and 11.9% respectively. Finally, several most effective efforts were combined to construct the optimal strain DW2ΔproBΔproJΔargR::ppnk1. In the optimal strain, the NADPH availability was improved and the expression levels of several essential genes for L-ornithine biosynthesis were upregulated, resulting in the enhancement of both L-ornithine and bacitracin production by 71.4% and 16.5% respectively. The final bacitracin production titer was 950 U/mL, which reached the level for industrial production.
Assuntos
Anti-Infecciosos Locais/metabolismo , Bacillus licheniformis/metabolismo , Bacitracina/metabolismo , Vias Biossintéticas/genética , Engenharia Metabólica/métodos , Ornitina/metabolismo , Bacillus licheniformis/genética , Deleção de Genes , Expressão GênicaRESUMO
Triclosan (TCS) is chemically designated as 5-chloro-2-(2,4-dichlorophenoxy) phenol and is considered as endocrine-disrupting chemical (EDC). The various diseases found due to exposure of TCS, have been linked with modulation of the human enoyl-acyl carrier protein-reductase (hER). However, the new protein targets for TCS other than hER, which are responsible for various diseases, are still unknown. In the present study, a bioinformatics approach was used to identify new possible targets for TCS. A text mining study was initially performed to understand the association of TCS in various biochemical processes. Discovery studio software 4.1 was used to carry out inverse virtual screening for 226 numbers of pathway proteins by docking study using CHARMm based docking tool, and twenty proteins were screened. CDOCKER energy values lower than -12.65â¯kcal/mol was considered for the screening of selected proteins. Three new proteins; Receptor-interacting protein 1 (RIP1), Apoptosis signal-regulating kinase 1 (ASK1) and B-cell lymphoma 2 (Bcl-2) from Apoptosis Signaling Pathway revealed best CDOCKER energy with triclosan which was -26.88, -23.34 and -22.96â¯kcal/mol respectively. The interaction of TCS with RIP1 and ASK1 were mostly hydrophobic; however, hydrogen bond type interaction was found in TCS/Bcl2 complex. Therefore, docking-based inverse virtual screening study suggests that TCS has other targets rather than hER, which can modulate various biochemical processes. The docking protocol was validated through evaluation of root-mean-square deviation (RMSD), key interaction score system (KISS) and the relationship between the docking energy and toxicity data available in ToxCast database. Low RMSD value (0.55 ËA) and high KISS score (0.66) along with higher correlation (R2â¯=â¯0.9798) between docking affinity and toxicity indicated that docking protocol can be used to optimize the binding energetics.
Assuntos
Anti-Infecciosos Locais/farmacologia , Disruptores Endócrinos/farmacologia , Simulação de Acoplamento Molecular/métodos , Proteínas/metabolismo , Software , Triclosan/farmacologia , Anti-Infecciosos Locais/metabolismo , Disruptores Endócrinos/metabolismo , Humanos , Interações Hidrofóbicas e Hidrofílicas , Ligantes , Modelos Moleculares , Ligação Proteica , Conformação Proteica , Proteínas/química , Proteínas/efeitos dos fármacos , Triclosan/metabolismoRESUMO
Biodegradability studies for the cationic surfactant cetylpyridinium chloride (CPC) are hampered by inhibitory effects on inoculum at prescribed test concentrations (10-20â¯mgâ¯organic carbon/L). In this study, we used 14C labeled CPC in the 28â¯d Headspace Test (OECD 310) and demonstrated that CPC was readily biodegradable (10->60% mineralization within a 10 day window) at test concentrations 0.006-0.3â¯mg/L with CPC as single substrate. Biodegradation efficiency was comparable over this concentration range. CPC inhibited degradation at 1â¯mg/L and completely suppressed inoculum activity at 3â¯mg/L. In an extensive sorbent modified biodegradation study we evaluated the balance between CPC bioaccessibility and toxicity. A non-inhibitory concentration of 0.1â¯mg/L CPC was readily biodegradable with 83% sorbed to SiO2, while biodegradation was slower when 96% was sorbed. SiO2 mitigated inhibitory effects of 1â¯mg/L CPC, reaching >60% biodegradation within 28â¯d; inhibitory effects were also mitigated by addition of commercial clay powder (illite) but this was primarily reflected by a reduced lag phase. At 10â¯mg/L CPC SiO2 was still able to mitigate inhibitory effects, but bioaccessibility seemed limited as only 20% biodegradation was reached. Illite limited bioaccessibility more strongly and was not able to sustain biodegradation at 10â¯mg/L CPC.
Assuntos
Anti-Infecciosos Locais/metabolismo , Biodegradação Ambiental , Cetilpiridínio/metabolismo , Minerais , Dióxido de Silício , TensoativosRESUMO
Hepatitis B virus (HBV) infection is a major risk factor for chronic liver disease, cirrhosis, and hepatocellular carcinoma (HCC) worldwide. While multiple hepatitis B drugs have been developed, build up of drug resistance during treatment or weak efficacies observed in some cases have limited their application. Therefore, there is an urgent need to develop substitutional pharmacological agents for HBV-infected individuals. Here, we identified cetylpyridinium chloride (CPC) as a novel inhibitor of HBV. Using computational docking of CPC to core protein, microscale thermophoresis analysis of CPC binding to viral nucleocapsids, and in vitro nucleocapsid formation assays, we found that CPC interacts with dimeric viral nucleocapsid protein (known as core protein or HBcAg) specifically. Compared with other HBV inhibitors, such as benzenesulfonamide (BS) and sulfanilamide (SA), CPC achieved significantly better reduction of HBV particle number in HepG2.2.15 cell line, a derivative of human HCC cells that stably expresses HBV. CPC also inhibited HBV replication in mouse hydrodynamic model system. Taken together, our results show that CPC inhibits capsid assembly and leads to reduced HBV biogenesis. Thus, CPC is an effective pharmacological agent that can reduce HBV particles.
Assuntos
Anti-Infecciosos Locais/metabolismo , Cetilpiridínio/metabolismo , Antígenos do Núcleo do Vírus da Hepatite B/metabolismo , Vírus da Hepatite B/efeitos dos fármacos , Vírus da Hepatite B/fisiologia , Montagem de Vírus/efeitos dos fármacos , Animais , Linhagem Celular , DNA Viral/sangue , Hepatócitos/virologia , Humanos , Camundongos Endogâmicos C57BL , Simulação de Acoplamento Molecular , Ligação ProteicaRESUMO
Triclocarban (TCC), as a broad spectrum antibacterial agent widely used in personal care products, has recently been recognized as environmental pollutant with the potential of adversely affecting wildlife and human health. However, the behavior of TCC in blood circulatory system and the potential toxicity of TCC at the molecular level have been poorly investigated. In this study, the effect of TCC on human serum albumin (HSA) and the binding mechanism of TCC to HSA were examined using spectroscopic techniques and molecular modeling methods. The fluorescence results suggested that the fluorescence of HSA was quenched by TCC through a static quenching mechanism and nonradiation energy transfer, and TCC was bound to HSA with moderately strong binding affinity via hydrophobic interaction based on the analysis of the thermodynamic parameters. The site marker competitive experiments revealed that TCC bound into subdomain IIA (site I) of HSA. In addition, the results obtained from the circular dichroism, Fourier transform infrared (FT-IR), 8-anilino-1-naphthalenesulfonic acid fluorescence, synchronous fluorescence, three-dimensional fluorescence spectra and dynamic light scattering suggested the change in the microenvironment and conformation of HSA during the binding reaction. Finally, the best binding mode of TCC and specific interaction of TCC with amino acid residues were determined using molecular docking and molecular dynamics simulations. In a word, the present studies can provide a way to help us well understand the transport, distribution and toxicity effect of TCC when it diffused in the human body. Communicated by Ramaswamy H. Sarma.
Assuntos
Carbanilidas/química , Carbanilidas/metabolismo , Modelos Moleculares , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Albumina Sérica Humana/química , Albumina Sérica Humana/metabolismo , Anti-Infecciosos Locais/química , Anti-Infecciosos Locais/metabolismo , Dicroísmo Circular , Humanos , Interações Hidrofóbicas e Hidrofílicas , Ligação Proteica , Conformação Proteica , Espectrometria de Fluorescência , Espectroscopia de Infravermelho com Transformada de Fourier , TermodinâmicaRESUMO
Acinetobacter baumannii is a Gram-negative opportunistic pathogen that causes diverse infections, including pneumonia, bacteremia, and wound infections. Due to multiple intrinsic and acquired antimicrobial-resistance mechanisms, A. baumannii isolates are commonly multidrug resistant, and infections are notoriously difficult to treat. The World Health Organization recently highlighted carbapenem-resistant A. baumannii as a "critical priority" for the development of new antimicrobials because of the risk to human health posed by this organism. Therefore, it is important to discover the mechanisms used by A. baumannii to survive stresses encountered during infection in order to identify new drug targets. In this study, by use of in vivo imaging, we identified hydrogen peroxide (H2O2) as a stressor produced in the lung during A. baumannii infection and defined OxyR as a transcriptional regulator of the H2O2 stress response. Upon exposure to H2O2, A. baumannii differentially transcribes several hundred genes. However, the transcriptional upregulation of genes predicted to detoxify hydrogen peroxide is abolished in an A. baumannii strain in which the transcriptional regulator oxyR is genetically inactivated. Moreover, inactivation of oxyR in both antimicrobial-susceptible and multidrug-resistant A. baumannii strains impairs growth in the presence of H2O2 OxyR is a direct regulator of katE and ahpF1, which encode the major H2O2-degrading enzymes in A. baumannii, as confirmed through measurement of promoter binding by recombinant OxyR in electromobility shift assays. Finally, an oxyR mutant is less fit than wild-type A. baumannii during infection of the murine lung. This work reveals a mechanism used by this important human pathogen to survive H2O2 stress encountered during infection.