RESUMO
Snakebite is a neglected disease with a high impact in tropical and subtropical countries. Therapy based on antivenom has limited efficacy in local tissue damage caused by venoms. Phospholipases A2 (PLA2) are enzymes that abundantly occur in snake venoms and induce several systemic and local effects. Furthermore, sulfur compounds such as thioesters have an inhibitory capacity against a snake venom PLA2. Hence, the objective of this work was to obtain a carbodithioate from a thioester with known activity against PLA2 and test its ability to inhibit the same enzyme. Benzyl 4-nitrobenzenecarbodithioate (I) was synthesized, purified, and characterized using as precursor 4-nitrothiobenzoic acid S-benzyl ester (II). Compound I showed inhibition of the enzymatic activity a PLA2 isolated from the venom of the Colombian rattlesnake Crotalus durissus cumanensis with an IC50 of 55.58 µM. This result is comparable with the reported inhibition obtained for II. Computational calculations were performed to support the study, and molecular docking results suggested that compounds I and II interact with the active site residues of the enzyme, impeding the normal catalysis cycle and attachment of the substrate to the active site of the PLA2.
Assuntos
Venenos de Crotalídeos/química , Crotalus , Simulação de Acoplamento Molecular , Inibidores de Fosfolipase A2/química , Fosfolipases A2/química , Proteínas de Répteis , Compostos de Enxofre/química , Animais , Proteínas de Répteis/antagonistas & inibidores , Proteínas de Répteis/químicaRESUMO
OBJECTIVE: To investigate the associations among salivary bacteria, oral emanations of volatile sulfur compounds, and academic-related chronic stress in healthy male subjects. MATERIALS AND METHODS: Seventy-eight healthy male undergraduate dental students were classified as stressed or not by evaluation of burnout, a syndrome attributed to academic-related chronic stress. This evaluation was carried out using the Maslach Burnout Inventory-Student Survey questionnaire. Oral emanations of hydrogen sulfide, methyl mercaptan, and dimethyl sulfide were measured using an Oral Chroma™ portable gas chromatograph. The amounts in saliva of total bacteria and seven bacteria associated with halitosis were quantified by qPCR. The in vitro production of H2S by S. moorei and/or F. nucleatum was also measured with the Oral Chroma™ instrument. RESULTS: The stressed students group showed increased oral emanations of hydrogen sulfide and dimethyl sulfide, together with higher salivary Solobacterium moorei levels (p < 0.05, Mann Whitney test). There were moderate positive correlations between the following pairs of variables: Fusobacterium nucleatum and S. moorei; F. nucleatum and hydrogen sulfide; Tannerella forsythia and F. nucleatum; T. forsythia and S. moorei. These correlations only occurred for the stressed group (p < 0.05, Spearman correlation). The in vitro experiment demonstrated that S. moorei increased H2S production by F. nucleatum (p < 0.05, ANOVA and Tukey's test). CONCLUSION: The increased amount of S. moorei in saliva, and its coexistence with F. nucleatum and T. forsythia, seemed to be responsible for increased oral hydrogen sulfide in the healthy male stressed subjects.
Assuntos
Voluntários Saudáveis , Saliva/microbiologia , Estresse Psicológico/microbiologia , Estudantes/psicologia , Compostos de Enxofre/química , Compostos de Enxofre/metabolismo , Adolescente , Bactérias/metabolismo , Halitose/microbiologia , Humanos , Masculino , Volatilização , Adulto JovemRESUMO
Diesel and naphtha samples were analyzed using ionic liquid (IL) columns to evaluate the best column set for the investigation of organic sulfur compounds (OSC) and nitrogen(N)-containing compounds analyses with comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry detector (GC×GC/TOFMS). Employing a series of stationary phase sets, namely DB-5MS/DB-17, DB-17/DB-5MS, DB-5MS/IL-59, and IL-59/DB-5MS, the following parameters were systematically evaluated: number of tentatively identified OSC, 2D chromatographic space occupation, number of polyaromatic hydrocarbons (PAH) and OSC co-elutions, and percentage of asymmetric peaks. DB-5MS/IL-59 was chosen for OSC analysis, while IL59/DB-5MS was chosen for nitrogen compounds, as each stationary phase set provided the best chromatographic efficiency for these two classes of compounds, respectively. Most compounds were tentatively identified by Lee and Van den Dool and Kratz retention indexes, and spectra-matching to library. Whenever available, compounds were also positively identified via injection of authentic standards.
Assuntos
Cromatografia Gasosa-Espectrometria de Massas/métodos , Líquidos Iônicos/química , Compostos de Nitrogênio/análise , Petróleo , Compostos de Enxofre/análise , Brasil , Cromatografia Gasosa-Espectrometria de Massas/normas , Hidrocarbonetos Aromáticos/análise , Hidrocarbonetos Aromáticos/química , Compostos de Nitrogênio/química , Padrões de Referência , Compostos de Enxofre/químicaRESUMO
Copper complexes with N3S donors mimic the CuM site of copper monooxygenases and react with O2 affording side-on cupric-superoxo complexes capable of H-abstraction from dihydroanthracene and THF. Spectroscopic and DFT data of the Cu-superoxos support a spin triplet ground state for the side-on complexes, as well as a hemilabile thioether.
Assuntos
Cobre/metabolismo , Oxigenases de Função Mista/metabolismo , Complexos Multienzimáticos/metabolismo , Compostos Organometálicos/metabolismo , Superóxidos/metabolismo , Benzimidazóis/química , Benzimidazóis/metabolismo , Domínio Catalítico , Cobre/química , Ligantes , Oxigenases de Função Mista/química , Estrutura Molecular , Complexos Multienzimáticos/química , Compostos de Nitrogênio/química , Compostos de Nitrogênio/metabolismo , Compostos Organometálicos/química , Compostos de Enxofre/química , Compostos de Enxofre/metabolismo , Superóxidos/químicaRESUMO
The structural, conformational, and configurational properties of 1,1,1-Trifluoro-N-(1,1,2,2,2-pentafluoroethyl) methanesulfinimidoyl chloride, CF3CF2NS(Cl)CF3 have been studied by vibrational spectroscopy [IR (vapor) and Raman (liquid)] and quantum chemical calculations [B3LYP, MP2 and B3PW91 levels of theory using the 6-311+G(d), 6-311+G(df) and 6-311+G(2df) basis sets]. According to these theoretical approximations, CF3CF2-N=S(Cl)CF3 exists in the gas phase as a mixture of a favored anticlinal form (CN bond anticlinal with respect to the CSCl bisector) with C1 symmetry and a less abundant syn conformer showing C1 symmetry as well (ΔG° ≈ 1.20 kcal mol(-1)). Due to the small contribution only a few corresponding vibrational modes of the syn conformer could be assigned confidently in the experimental spectra. Compared to CF3CF2-N=S(F)CF3, the replacement of F by Cl produces a clear change in NS bond length and the corresponding stretching frequency, without affecting the conformational properties.
Assuntos
Etilaminas/química , Conformação Molecular , Compostos de Enxofre/química , Vibração , Imidas/química , Modelos Moleculares , Enxofre/química , TermodinâmicaRESUMO
Density functional calculations indicate that protonation of a µ3-S atom in cubanoid clusters [Fe4S4X4](2-) leads to a large extension of one Fe-S(H) bond such that the SH ligand is doubly-bridging, µ-SH. Triply-bridging SH in these clusters is unstable, relative to µ-SH. The theory for the geometric and electronic structures of the protonated [Fe4S4X4](2-) clusters (X = Cl, SEt, SMe, SPh, OMe, OPh) is presented in this paper. The principal results are (1) the unique Fe atom in [Fe4S3(SH)X4](-) is three-coordinate, with planar or approximately planar stereochemistry, (2) approximately equi-energetic endo and exo isomers occur for pyramidal µ-SH, (3) the structural changes caused by protonation reverse without barrier on deprotonation, (4) the most stable electronic states have S = 0 and oppositely signed spin densities on the Fe atoms bearing the µ-SH bridge, (5) interconversions between endo and exo isomers, and between ground and excited states, occur through concerted lengthenings and shortenings of Fe-S(H) interactions, on relatively flat energy surfaces, (6) protonation of an X ligand does not change the characteristics of protonation of µ3-S. Experimental tests of this theory are suggested, and applications discussed.
Assuntos
Compostos de Ferro/química , Compostos de Enxofre/química , Enxofre/química , Elétrons , Isomerismo , Modelos Moleculares , PrótonsRESUMO
This study aims at modifying dual-cure composite cements by adding thio-urethane oligomers to improve mechanical properties, especially fracture toughness, and reduce polymerization stress. Thiol-functionalized oligomers were synthesized by combining 1,3-bis(1-isocyanato-1-methylethyl)benzene with trimethylol-tris-3-mercaptopropionate, at 1:2 isocyanate:thiol. Oligomer was added at 0, 10 or 20 wt% to BisGMA-UDMA-TEGDMA (5:3:2, with 25 wt% silanated inorganic fillers) or to one commercial composite cement (Relyx Ultimate, 3M Espe). Near-IR was used to measure methacrylate conversion after photoactivation (700 mW/cm(2) × 60s) and after 72 h. Flexural strength and modulus, toughness, and fracture toughness were evaluated in three-point bending. Polymerization stress was measured with the Bioman. The microtensile bond strength of an indirect composite and a glass ceramic to dentin was also evaluated. Results were analyzed with analysis of variance and Tukey's test (α = 0.05). For BisGMA-UDMA-TEGDMA cements, conversion values were not affected by the addition of thio-urethanes. Flexural strength/modulus increased significantly for both oligomer concentrations, with a 3-fold increase in toughness at 20 wt%. Fracture toughness increased over 2-fold for the thio-urethane modified groups. Contraction stress was reduced by 40% to 50% with the addition of thio-urethanes. The addition of thio-urethane to the commercial cement led to similar flexural strength, toughness, and conversion at 72h compared to the control. Flexural modulus decreased for the 20 wt% group, due to the dilution of the overall filler volume, which also led to decreased stress. However, fracture toughness increased by up to 50%. The microtensile bond strength increased for the experimental composite cement with 20 wt% thio-urethane bonding for both an indirect composite and a glass ceramic. Novel dual-cured composite cements containing thio-urethanes showed increased toughness, fracture toughness and bond strength to dentin while demonstrating reduced contraction stress. All of these benefits are derived without compromising the methacrylate conversion of the resin component. The modification does not require changing the operatory technique.
Assuntos
Resinas Compostas/química , Cimentos de Resina/química , Compostos de Enxofre/química , Uretana/química , Ácido 3-Mercaptopropiônico/química , Peróxido de Benzoíla/química , Bis-Fenol A-Glicidil Metacrilato/química , Cerâmica/química , Colagem Dentária , Dentina/ultraestrutura , Módulo de Elasticidade , Humanos , Isocianatos/química , Cura Luminosa de Adesivos Dentários/métodos , Teste de Materiais , Metacrilatos/química , Maleabilidade , Polietilenoglicóis/química , Polimerização , Ácidos Polimetacrílicos/química , Poliuretanos/química , Autocura de Resinas Dentárias/métodos , Silanos/química , Estresse Mecânico , Propriedades de Superfície , Resistência à Tração , para-Aminobenzoatos/químicaRESUMO
Volatile sulphur compounds (VSC) are the gases mainly responsible for halitosis (bad breath). The aim of this research was to evaluate the effects of medicinal plants on halitosis control. Two commonly used plants were tested: Curcuma zedoaria and Camellia sinensis (green tea). These plants were prepared as an aqueous solution and used as mouthwashes, compared with a standard mouthwash of 0.12% chlorhexidine gluconate and a placebo (water). The experiment was conducted with 30 volunteers from the School of Dentistry of São Jose dos Campos, Univ. Estadual Paulista - UNESP, SP, Brazil. Each volunteer tested the four mouthwashes. The Cysteine Challenge Method, modified for this study, was used for initial breath standardization. Four breath assessments were conducted after volunteers rinsed orally with acetylcysteine: one before the test mouthwash was used; the second, one minute after its use; a third 90 minutes later; and the last 180 minutes later. The results showed that chlorhexidine gluconate lowered VSC production immediately, and that this effect lasted up to 3 hours, while the tested plants had immediate inhibitory effects but no residual inhibitory effects on VSC. We concluded that Curcuma zedoaria and Camellia sinensis, prepared as infusions and used as mouthwashes, did not have a residual neutralizing effect on VSC.
Assuntos
Adulto , Feminino , Humanos , Masculino , Camellia sinensis/química , Curcuma/química , Halitose/prevenção & controle , Antissépticos Bucais/uso terapêutico , Análise de Variância , Brasil , Clorexidina/análogos & derivados , Clorexidina/uso terapêutico , Compostos de Enxofre/química , Fatores de Tempo , Resultado do TratamentoRESUMO
Sequential activation of different reversible exchange reactions in a dynamic combinatorial library allows directed exploration of the chemical space: initially a macrocyclic scaffold is selected by the template and finally side chain and conformational constrains are introduced into such a scaffold.
Assuntos
Hidrazonas/química , Compostos Macrocíclicos/química , Compostos de Enxofre/química , Técnicas de Química Combinatória , Conformação Molecular , Estrutura MolecularRESUMO
Volatile sulphur compounds (VSC) are the gases mainly responsible for halitosis (bad breath). The aim of this research was to evaluate the effects of medicinal plants on halitosis control. Two commonly used plants were tested: Curcuma zedoaria and Camellia sinensis (green tea). These plants were prepared as an aqueous solution and used as mouthwashes, compared with a standard mouthwash of 0.12% chlorhexidine gluconate and a placebo (water). The experiment was conducted with 30 volunteers from the School of Dentistry of São Jose dos Campos, Univ. Estadual Paulista - UNESP, SP, Brazil. Each volunteer tested the four mouthwashes. The Cysteine Challenge Method, modified for this study, was used for initial breath standardization. Four breath assessments were conducted after volunteers rinsed orally with acetylcysteine: one before the test mouthwash was used; the second, one minute after its use; a third 90 minutes later; and the last 180 minutes later. The results showed that chlorhexidine gluconate lowered VSC production immediately, and that this effect lasted up to 3 hours, while the tested plants had immediate inhibitory effects but no residual inhibitory effects on VSC. We concluded that Curcuma zedoaria and Camellia sinensis, prepared as infusions and used as mouthwashes, did not have a residual neutralizing effect on VSC.