Comparison between E-test and CLSI broth microdilution method for antifungal susceptibility testing of Candida albicans oral isolates

Trinta Candida albicans isoladas de pacientes portadores de candidose oral e 30 Candida albicans isoladas de indivíduos controle foram estudadas. Testes de susceptibilidade in vitro foram realizados com anfotericina B, fluconazol, 5-flucitosina e itraconazol pelo método do Clinical and Laboratorial Standars Institute (CLSI) e por E-test. Os resultados obtidos foram analisados e comparados. Os valores de CIM foram semelhantes para amostras isoladas de pacientes portadores de candidose oral e indivíduos controle. A concordância entre os dois métodos foi de 66,7% para a anfotericina B, 53,33% para o fluconazol, 65% para a flucitosina e 45% para o itraconazol. De acordo com estes resultados, o método do E-test poderia ser uma alternativa para a triagem de casos de rotina pela sua simplicidade. Entretanto, este método não pode ser considerado como um substituto para o método de referência do CLSI.Thirty Candida albicans isolated from oral candidosis patients and 30 C. albicans isolated from control individuals were studied. In vitro susceptibility tests were performed for amphotericin B, fluconazole, 5-flucytosine and itraconazole through the Clinical and Laboratorial Standards Institute (CLSI) reference method and E test system. The results obtained were analyzed and compared. MIC values were similar for the strains isolated from oral candidosis patients and control individuals. The agreement rate for the two methods was 66.67% for amphotericin B, 53.33% for fluconazole, 65% for flucytosine and 45% for itraconazole. According to our data, E test method could be an alternative to trial routine susceptibility testing due to its simplicity. However, it can not be considered a substitute for the CLSI reference method

Comparação entre E-test e o método da microdiluição do CLSI para teste de susceptibilidade a antifúngicos de isolados orais de Candida albicans

Thirty Candida albicans isolated from oral candidosis patients and 30 C. albicans isolated from control individuals were studied. In vitro susceptibility tests were performed for amphotericin B, fluconazole, 5-flucytosine and itraconazole through the Clinical and Laboratorial Standards Institute (CLSI) reference method and E test system. The results obtained were analyzed and compared. MIC values were similar for the strains isolated from oral candidosis patients and control individuals. The agreement rate for the two methods was 66.67% for amphotericin B, 53.33% for fluconazole, 65% for flucytosine and 45% for itraconazole. According to our data, E test method could be an alternative to trial routine susceptibility testing due to its simplicity. However, it can not be considered a substitute for the CLSI reference method.Trinta Candida albicans isoladas de pacientes portadores de candidose oral e 30 Candida albicans isoladas de indivíduos controle foram estudadas. Testes de susceptibilidade in vitro foram realizados com anfotericina B, fluconazol, 5-flucitosina e itraconazol pelo método do Clinical and Laboratorial Standars Institute (CLSI) e por E-test. Os resultados obtidos foram analisados e comparados. Os valores de CIM foram semelhantes para amostras isoladas de pacientes portadores de candidose oral e indivíduos controle. A concordância entre os dois métodos foi de 66,7% para a anfotericina B, 53,33% para o fluconazol, 65% para a flucitosina e 45% para o itraconazol. De acordo com estes resultados, o método do E-test poderia ser uma alternativa para a triagem de casos de rotina pela sua simplicidade. Entretanto, este método não pode ser considerado como um substituto para o método de referência do CLSI

pH effect on the synthesis of different size silver nanoparticles evaluated by DLS and their size-dependent antimicrobial activity

This paper reports citrate-stabilized silver nanoparticles (AgNPs) synthesized by nitrate ion chemical reduction with sodium borohydride, at different pHs (2–9). The AgNPs synthesized by this method exhibited size distribution from 5 to 249 nm, depending on pH, as determined by dynamic light scattering, and morphology spherical, as determined by transmission electron microscopy. In pH range 3–7 occurred aggregation of the nanoparticles. The size distribution depending on pH was determined by dynamic light scattering. The zeta potential was determined, and the colloidal stability was correlated with nanoparticles aggregation at different pHs. The size-dependent antimicrobial activity was evaluated for two solutions, wherein both samples exhibited antimicrobial activity, although the smallest AgNPs without agglomeration have enhanced antimicrobial properties.Keywords: Silver Nanoparticles, Zeta Potential, Dynamic Light Scattering, Size Distribution, Antimicrobial Activity

Giant extracellular hemoglobin of Glossoscolex paulistus: an extraordinary supramolecular hemoprotein system

Giant extracellular hemoglobins are considered the summit of complexity in systems that carry oxygen, constituting an extraordinary model system to the study of hemoproteins. This class includes the hemoglobin of the annelid Glossoscolex paulistus that presents high cooperativity, great oligomeric and redox stabilities and ability of oligomeric reassociation. These properties have motivated evaluations about its utilization as prototype of artificial blood and biosensor. Kinetic studies involving autoxidation and detailed spectroscopic characterizations of its ferrous and ferric species have propitiated information about the structure-activity relationship of this macromolecule. The present review analyzes several biochemical issues, evaluating the state-of-art of this subject.CNP

Ferric species of the giant extracellular hemoglobin of Glossoscolex paulistus as function of pH: an EPR study on the irreversibility of the heme transitions

The present article is focused on the transitions of ferric heme species of the giant extracellular hemoglobin of Glossoscolex paulistus (HbGp) induced by successive alterations in pH, involving alkaline and acid mediums. Electron paramagnetic resonance (EPR) is the spectroscopy used to evaluate the transitions that occur in the first coordination sphere of ferric ion as a consequence of ligand changes in a wide range of pH, since this tool is very sensitive to slight changes that occur in the heme pocket of paramagnetic species. This approach is adequate to obtain information regarding the reversibility/irreversibility that involves the heme transitions induced by pH, since the degree of reversibility is associated to the intensity of the changes that occur in the spatial configuration of the polypeptide chains, which is clearly associated to the first coordination sphere. The results demonstrate a significant degree of irreversibility of heme transitions, since the final species, which do not present any change after 6 h of its respective formations, are quite different of the initial species. The results denote that the more stable species are the bis-histidine (hemichrome) and pentacoordinate species, due to the properties of their ligands and to the mechanical influence of the respective subunits. EPR spectra allow to distinguish the types of hemichrome species, depending on the reciprocal orientation between the histidine axial ligands, in agreement with Walker's Classification [Walker, F.A., 1999. Magnetic spectroscopic (EPR, ESEEM, Mössbauer, MCD and NMR) studies of low-spin ferriheme centers and their corresponding heme proteins. Coord. Chem. Rev. 185–186, 471–534]. However, these transitions are not completed, i.e., the appearance of a determined species does not mean the total consumption of its precursor species, implying the coexistence of several types of species, depending on pH. Furthermore, it is possible to conclude that a “pure” EPR spectrum of aquomet ferric species is an important indicator of a high level of conservation referent to the “native” configuration of whole hemoglobin, which is only encountered at pH 7.0. The results allow to infer important physico-chemical properties as well as to evaluate aspects of the structure–activity relationship of this hemoprotein, furnishing information with respect to the denaturation mechanism induced by drastic changes in pH. These data are very useful since HbGp has been proposed as prototype of substitute of blood, thus requiring wide knowledge about its structural and chemical properties.CNPqPRONEX/FAPESP/CNPq (03/09859-2

Ligand changes in ferric species of the giant extracellular hemoglobin of Glossoscolex paulistus as function of pH: correlations between redox, spectroscopic and oligomeric properties and general implications with different hemoproteins

The present review is focused on the relationship between oligomeric and heme properties of HbGp, emphasizing the characteristics that can be generalized to other hemoproteins. This study represents the state-of-the-art with respect to the approaches for investigating giant extracellular hemoglobins as well as the correlation between oligomeric assembly alterations and their consequent changes in the first coordination sphere. A wide introduction focused on the properties of this hemoglobin is developed. Indeed, this hemoprotein is considered an interesting prototype of blood substitute and biosensor due to its peculiar properties, such as resistance to autoxidation and oligomeric stability. Previous studies by our group employing UV-vis, EPR and CD spectroscopies have been revised in a complete approach, in agreement with recent and relevant data from the literature. In fact, a consistent and inter-related spectroscopic study is described propitiating a wide assignment of "fingerprint" peaks found in the techniques evaluated in this paper. This review furnishes physicochemical information regarding the identification of ferric heme species of hemoproteins and metallic complexes through their spectroscopic bands. This effort at the attribution of UV-vis, EPR and CD peaks is not restricted to HbGp, and includes a comparative analysis of several hemoproteins involving relevant implications regarding several types of iron-porphyrin systems

The Methylene Blue Self-aggregation in Water/Organic Solvent Mixtures: Relationship Between Solvatochromic Properties and Singlet Oxygen Production

In this work is presented a spectrophotometric investigation focused on the solvatochromic effects upon Methylene Blue (MB). Measurements were carried out in four different water/organic solvent mixtures: low polarity protic solvent (ethanol), polar non-protic solvent (acetonitrile), highly polar protic solvent (glycerol), and non-polar solvent (dioxane). The results showed that the photophysical behavior of MB is highly affected by self-aggregates formation at 80% of water/organic solvent blends. Besides polarity, the protic character and the coordinating properties of the solvent molecules are the key parameters for its photophysical behavior, since the sulfur atom of the cationic structure can act as a coordination center due to its Lewis acid character. In fact, water and acetonitrile coordinating properties have proved to be important to determine MB interactions intensity and its spectroscopic properties as singlet oxygen emission. It was observed that an increase of the amount of the organic solvent resulted in an enhancement of the singlet oxygen emission intensity. The presence of the water increases the dielectric constant of the medium and favors the self-aggregation process. Besides, the water molecules can act as a quencher and it decreases the quantum yield of the fluorescence of MB.FAPESPCNPqFarma Service BioExtract LtdaUniv Fed Sao Joao del Rei, Dept Zootecnia DEZOO, Campus Dom Bosco, BR-36301160 Sao Joao Del Rei, MG, BrazilUniv Vale Paraiba, Ave Shishima Hifumi 2911, BR-12244000 Sao Paulo, BrazilUniv Fed Sao Paulo, Dept Quim, Rua Prof Arthur Riedel 275, BR-09972270 Sao Paulo, BrazilUniv Sao Paulo, Dept Bioquim, Inst Quim, Ave Prof Lineu Prestes 748, BR-05508900 Sao Paulo, SP, BrazilUniv Tecnol Fed Parana, Campus Apucarana,Rua Marcilio Dias 635, BR-86812460 Apucarana, Parana, BrazilUniv Fed Santa Catarina, BR-88040900 Florianopolis, SC, BrazilUniv Estadual Maringa, Dept Quim, Av Colombo 5790,Zona 07, BR-87020900 Maringa, Parana, BrazilUniv Fed Rio de Janeiro, Campus Macae,Rua Aloisio da Silva Gomes 50, BR-27930560 Rio De Janeiro, BrazilUniv Estadual Campinas, Inst Quim, BR-13083970 Sao Paulo, BrazilUniv Fed Rio Grande, Escola Quim & Alimentos, Campus Carreiros Pavilhao Quim, BR-96201900 Rio Grande, RS, BrazilUniv Fed ABC, Ctr Engn Modelagem & Ciencias Sociais Aplicadas, Ave Estados 5001, BR-09210580 Sao Paulo, BrazilUniv Fed ABC, Ctr Ciencias Nat & Humanas, Ave Estados 5001, BR-09210580 Sao Paulo, BrazilUniv Fed Sao Paulo, Dept Quim, Rua Prof Arthur Riedel 275, BR-09972270 Sao Paulo, BrazilFAPESP: JP 04/02193-1FAPESP: 02/00272-6FAPESP: 06/56701-3FAPESP: 2005/51597-8CNPq: 474019/2012-8]CNPqFarma Service BioExtract LtdaWeb of Scienc

Composição química e avaliação das atividades antioxidante e antimicrobiana do óleo essencial das folhas de Hyptidendron canum (Pohl ex Benth.) R.Harley

Hyptidendron canum (Pohl ex Benth) R. Harley, commonly known as “catinga-de-bode-do-cerrado” is a species popularly used as antifungal and anti-inflammatory. Knowing that essential oils (OE) stand out for these and other bioactivities (analgesic, microbial, among others), the objective was to evaluate the content and characterize the OE of the leaves of H. canum, as well as to evaluate their antimicrobial and antioxidant activities. The OE was extracted by hydrodistillation and used by gas chromatography. Antimicrobial activity was evaluated under the microorganisms Staphylococcus aureus, Escherischia coli, Candida albicans, C. glabrata and C. krusei and an antioxidant activity by the DPPH method. The major constituents were: β-macrocarpene, γ-muurolene, (E) -cariophylene. The results showed that this OE has fungicidal activity (44.68 μg / mL) and antioxidant. Thus, this OE is a promising natural source as an antioxidant and antifungal.Hyptidendron canum (Pohl ex Benth) R.Harley, comumente conhecida como “catinga-de-bode-do-cerrado” é uma espécie utilizada popularmente como antifúngico e anti-inflamatório. Sabendo que os óleos essenciais (OE) se destacam por estas e outras bioatividades (analgésicas, microbianas, dentre outras), objetivou-se avaliar o teor e caracterizar o OE das folhas de H. canum, bem como avaliar suas potenciais atividades antimicrobiana e antioxidante. O OE foi extraído por hidrodestilação e caracterizado por cromatografia gasosa. A atividade antimicrobiana foi avaliada sob os microrganismos Staphylococcus aureus, Escherischia coli, Candida albicans, C. glabrata e C. krusei e a atividade antioxidante pelo método DPPH. Os constituintes majoritários foram: β-macrocarpeno, γ-muuroleno, (E)-cariofileno. Os resultados demonstraram que este OE possui atividade fungicida (44,68 μg/mL) e antioxidante. Assim, este OE é uma promissora fonte natural como antioxidante e antifúngico