High-throughput screening methodologies to estimate lipid content in oleaginous yeasts use Nile red fluorescence in a given solvent and optimized excitation/emission wavelengths. However, Nile red fluorescence stabilization has been poorly analyzed, and high variability occurs when relative fluorescence is measured immediately or a few minutes after dye addition. The aim of this work was to analyze the fluorescence of Nile red at different incubation times using a variety of solvents and oleaginous/non-oleaginous yeast strains.
View Article and Find Full Text PDFBiofilms provide an ideal environment for protecting the microbial cells from damage caused by humoral and cellular immune system components, promoting resistance, infections and increasing mortality and morbidity of patients in health facilities. In an attempt to provide an innovative solution for preventing contamination in hospital environments, this study evaluated nine structural complementary fluorescent benzimidazo[1,2-α]quinolines as bifunctional agents that both detect and have biocidal activity against yeast biofilms on stainless steel surfaces. The benzimidazoles' staining capability was determined by a fluorescence microscopy study and spraying the substance on yeast biofilm contaminated stainless steel surfaces.
View Article and Find Full Text PDFThis study presents a new method for visualization of Oxyuris equi eggs collected by means of a clear adhesive tape applied to the perianal region of horses. The obtained results indicate that this protocol permits a quick, easy, clear and selective visualization of Oxyuris equi eggs even in the presence of feces and other material. Another advantage of this method is that it can be used with fluorescent dyes solubilized in water, which will stain biologic material without dissolving or altering the adhesive tape and is also environmentally safe.
View Article and Find Full Text PDFThree novel fluorescent dyes were evaluated for the detection of latent fingermarks on different types and colors of adhesive tapes. Compared with the conventional reagents used to reveal latent fingermarks on these surfaces, these new fluorescent dyes have many advantages. They are highly selective to fingermarks, require only a simple procedure, do not need pre- or post-treatment, have high thermal and photochemical stability, are low in cost and use only water as a solvent.
View Article and Find Full Text PDFIntroduction: Sporothrix schenckii is a thermal dimorphic pathogenic fungus causing a subcutaneous mycosis, sporotrichosis. Nitrocoumarin represents a fluorogenic substrate class where the microbial nitroreductase activity produces several derivatives, already used in several other enzyme assays. The objective of this study was the analysis of 6-nitrocoumarin (6-NC) as a substrate to study the nitroreductase activity in Sporothrix schenckii.
View Article and Find Full Text PDFTwo Schiff bases were synthesized by reaction of 2-(4'-aminophenyl)benzoxazole derivatives with 4-N,N-diethylaminobenzaldehyde. UV-visible (UV-vis) and steady-state fluorescence in solution were applied in order to characterize its photophysical behavior. The Schiff bases present absorption in the UV region with fluorescence emission in the blue-green region, with a large Stokes' shift.
View Article and Find Full Text PDFThe microscopic morphology of Fonsecaea pedrosoi ATCC46428 was observed using two benzazole derivatives, 2-(2'-hydroxyphenyl)benzoxazole and 2-(5'-amino-2'-hydroxyphenyl)benzoxazole, which emit intense fluorescence by a proton transfer mechanism in the electronically excited state (ESIPT). The cell surface could be successfully stained with fluorescent dye solutions of 10 microM-10 mM using two different fast and cost-effective procedures. At these concentrations, any structure or dye crystallization could be observed.
View Article and Find Full Text PDFThe aim of this work was to investigate if the indomethacin ethyl ester (IndOEt) released from lipid-core nanocapsules (NC) is converted into indomethacin (IndOH) in the intestine lumen, intestine wall or after the particles reach the blood stream. NC-IndOEt had monomodal size distribution (242 nm; PDI 0.2) and zeta potential of -11 mV.
View Article and Find Full Text PDFThe development of azole antifungals has allowed for the treatment of several fungal infections. However, the use of these compounds is restricted because of their hepatotoxicity or because they need to be administered together with other drugs in order to prevent resistance to monotherapy. Benzoxazole derivatives are among the most thriving molecular prototypes for the development of antifungal agents.
View Article and Find Full Text PDFThere are few studies on the biological activity of aminohydroxy derivates of 1,4-naphthoquinone (1,4-NQ) on prokaryotic and eukaryotic cells. We determined the mutagenic activity of 5-amino-8-hydroxy-1,4-naphthoquinone (ANQ) and 5-amino-2,8-dihydroxy-1,4-naphthoquinone (ANQ-OH) as compared to the unsubstituted 1,4-NQ in Salmonella/microsome assay. Potential mutagenic and recombinogenic effects and cytotoxicity were analyzed in haploid and diploid cultures of the yeast Saccharomyces cerevisiae.
View Article and Find Full Text PDFFluorescent polymers were used to prepare innovative formulations with the objective of verifying the chemical composition of the particle/water interface of nanocapsules at a molecular level. The benzazole dyes distinguish between apolar and polar/protic environments. Comparing the fluorescent behavior of benzoxazole-loaded nanocapsules (entrapped dye) with that of fluorescent-polymeric nanocapsules (chemically bound dye), the results indicated that the latter was exposed to a different environment than that to which the entrapped dye was exposed.
View Article and Find Full Text PDFThe 2-(4'-isothiocyanate-2'-hydroxyphenyl)benzoxazole dye was successfully applied as label of rice proteins during the alkaline extraction of starch. Direct fluorescence measurements were used to observe the presence of proteins labelled in different steps of rice starch extraction. The results were compared to those obtained with the well-known biuret colorimetric test.
View Article and Find Full Text PDFThree new benzazole isothiocyanate fluorescent dyes, 2-(4'-isothiocyanate-2'-hydroxyphenyl)benzoxazole, 2-(4'-isothiocyanate-2'-hydroxyphenyl)benzothiazole and 2-(4'-isothiocyanate-2'-hydroxyphenyl)benzimidazole were synthesised, purified until optical purity grade and characterised by spectroscopic techniques. UV/VIS and steady-state fluorescence were also applied to characterise the photophysical behaviour of the dyes. These dyes exhibit an intense fluorescence emission with a large Stokes shift, inherent to the class of benzazoles which relax by the excited state intramolecular proton transfer (ESIPT) mechanism.
View Article and Find Full Text PDFThe antimicrobial effect of 5 naphthoquinones was tested against the phytopathogenic bacteria Erwinia carotovora. Disk diffusion tests and determination of minimal inhibitory concentrations (MIC) indicate that the compound naphthazarin (NTZ) has the best antibacterial activity among the naphthoquinones tested. Studies on the mode of action indicate the effect of NTZ was bactericidal at 10 microg/mL.
View Article and Find Full Text PDFThe Sonogashira coupling of 2-bromopyridine with 8-quinolinyl-acetylene affords 2-pyridinyl-8-quinolinyl-acetylene (1) in high yields. The chloropalladation of 1 with Li(2)PdCl(4) in methanol at room temperature affords the pincer palladacycle (C(5)H(4)N-2-C=C(Cl)-8-C(9)H(6)kappaN,kappaC,kappaN)PdCl (2) in 63% yield. The X-ray molecular structure of (2) shows that it is totally flat and that it is associated in pairs though pi-stacking between alternate pyridine-quinoline moieties (3.
View Article and Find Full Text PDFDiels-Alder reactions of (S)-2-(p-tolylsulfinyl)-1,4-benzoquinone (1a) with cyclic (cyclopentadiene and cyclohexadiene) and acyclic dienes (1-[(trimethylsilyl)oxy]-1,3-butadiene and trans-piperylene) under different thermal and Lewis acid conditions are reported. Chemoselectivity (reactions on C(2)-C(3) versus C(5)-C(6) double bonds) is mainly related to the cyclic (on C(5)-C(6)) or acyclic (on C(2)-C(3)) structure of the diene. The high pi-facial selectivity observed could be controlled by choosing adequate experimental conditions.
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