Determination of epristeride by its quenching effect on the fluorescence of L -tryptophan

Gong, Aiqin; Zhu, Xiashi

doi:10.1016/j.jpha.2013.05.001

Cited by 13 publications

(7 citation statements)

References 10 publications

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“…Absorption spectroscopy can be used to distinguish between two quenching mechanisms. The changes observed in the absorption spectra (Figure ) are in a good agreement with the static quenching hypothesis. ,− For the dynamic quenching, the absorption spectra of the fluorophore are not changed and only the excited state of the fluorophore is influenced by the quencher, while for the static quenching a conjugate is formed between the ground-state of the fluorophore and the quencher, which would influence the absorption spectra of the fluorophore. As can be seen from Figure , as the concentration of Au NPs increases, the intensity of the Pir absorption bands enhances with a blue shift in the wavelength maxima.…”

Section: Resultssupporting

confidence: 77%

Combined Experimental and Computational Study of the In Situ Adsorption of Piroxicam Anions on the Laser-Generated Gold Nanoparticles

et al. 2017

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Gold nanoparticle–piroxicam anion conjugates (Au NP–Pir) were synthesized in a green method using laser ablation of a gold foil in an aqueous solution of anionic piroxicam (NaPir). The produced Au NP–Pir conjugates were characterized by different spectroscopic techniques and transmission electron microscopy. The fluorescence and absorption spectra of Au NP–Pir colloidal solution were recorded at different concentrations of the Au NPs to investigate the effect of conjugation on the spectral properties of both the free Pir anion and Au NPs. Comparing the FT-IR spectrum of the colloidal solution of Au NP–Pir with that of the solution of the free Pir anion indicates that this anion binds to the surface of Au NPs through its different binding sites, viz., the pyridyl nitrogen atom, the SO2 group, and the amide oxygen atom. To support the experimental observations, theoretical calculations were also performed to evaluate the interaction of different binding sites of Pir with one Au atom and the effect of this interaction on the IR spectrum of Pir. In a more realistic theoretical study, the optimized geometry of Pir on the Au(111) surface was calculated, and its orientation toward the surface of Au was obtained. The calculations show that the pyridyl ring of Pir prefers to orient perpendicular to the surface of Au, and the O atoms of the SO2 and amide groups are responsible for the interaction with the surface. The cytotoxic effect of the free Pir anion and Au NP–Pir conjugates against the Jurkat T-cells was studied using an MTT assay. The results show that only the Au NP–Pir conjugates have significant anticancer activity against the Jurkat T-cells with an IC50 value of 33.8 ± 2 μg/mL. In comparison with the pure Au NPs and free Pir, the Au NP–Pir conjugates show a significant antimicrobial activity against two pathogens including Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus).

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Section: Resultssupporting

confidence: 77%

Combined Experimental and Computational Study of the In Situ Adsorption of Piroxicam Anions on the Laser-Generated Gold Nanoparticles

et al. 2017

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“…K sv values were evaluated from the slope of the plot (Geethanjali et al, 2015). Linearity of the plots was tested by calculation of the correlation coefficient (Gong & Zhu, 2013;Wahba, El-Enany & Belal, 2015).…”

Section: Fluorescence Spectroscopic Measurementsmentioning

confidence: 99%

Spectroscopic and electrochemical study of interactions between DNA and different salts of 1,4-dihydropyridine AV-153

Ļeonova

Shvirksts

Borisovs

et al. 2020

PeerJ

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1,4-dihydropyridines (1,4-DHP) possess important biochemical and pharmacological properties, including antimutagenic and DNA-binding activity. The latter activity was first described for water-soluble 1,4-DHP with carboxylic group in position 4, the sodium salt of the 1,4-DHP derivative AV-153 among others. Some data show the modification of physicochemical properties and biological activities of organic compounds by metal ions that form the salts. We demonstrated the different affinity to DNA and DNA-protecting capacity of AV-153 salts, depending on the salt-forming ion (Na, K, Li, Rb, Ca, Mg). This study aimed to use different approaches to collate data on the DNA-binding mode of AV-153-Na and five other AV-153 salts. All the AV-153 salts in this study quenched the ethidium bromide and DNA complex fluorescence, which points to an intercalation binding mode. For some of them, the intercalation binding was confirmed using cyclic voltammetry and circular dichroism spectroscopy. It was shown that in vitro all AV-153 salts can interact with four DNA bases. The FTIR spectroscopy data showed the interaction of AV-153 salts with both DNA bases and phosphate groups. A preference for base interaction was observed as the AV-153 salts interacted mostly with G and C bases. However, the highest differences were detected in the spectral region assigned to phosphate groups, which might indicate either conformational changes of DNA molecule (B form to A or H form) or partial denaturation of the molecule. According to the UV/VIS spectroscopy data, the salts also interact with the human telomere repeat, both in guanine quadruplex (G4) and single-stranded form; Na and K salts manifested higher affinity to G4, Li and Rb –to single-stranded DNA.

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“…8b). For the dynamic mode, there were no observed changes to the UV spectra of basic fuchsin dye with or without valsartan at pH 6 (Gong and Zhu, 2013).…”

Section: The Type Of Fluorescence Quenching and Effect Of Temperaturementioning

confidence: 87%

“…The solutions so obtained were filtrated by Whatman ® quantitative filter paper, ashless, Grade 41 (Merck, Darmstadt, Germany), before washing and diluting to 50 mL using ethanol. (Gong and Zhu, 2013) Initially, the drug-free serum and urine samples were obtained from Rizgary Hospital (Erbil-K. R. of Iraq) and kept at −20°C until analysis and thawed to lab temperature before use. The serum and urine samples were individually diluted by 1000-and 500-fold using deionized water.…”

Section: Sample Preparationmentioning

confidence: 99%

New Fluorescence Quenching Approach for Determination of Valsartan in Certain Tablets and Spiked Biological Fluids

Ali

2020

ARO

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A new, simple, selective, sensitive, fast, economical, and reliable fluorescence quenching method for the quantitation of valsartan was investigated using basic fuchsin act as a fluorometric dye. The method was depended on the detection quenching influence of valsartan on the fluorescence intensity of basic fuchsin and the reaction between valsartan and basic fuchsin in a McIlvaine buffer medium at pH = 6 to yield a new basic fuchsin–valsartan non-fluorescent complex. The excitation and emission of basic fuchsin fluorescence signal were identified at 535 and 728 nm, respectively. A fluorescence quenching value (ΔF) displayed a very good linear relationship (R2 = 0.9992) with valsartan concentration ranging from 0.003 to 3 μg/mL, a detection limit as low as 0.0009 μg/mL with a high precision and accuracy (RSD% <3). Significantly, no interference effect was found due to the presence of other ingredients commonly found in medical formulations. The acquired data were statistically compared with those acquired from reported chromatographic method and were observed to be in excellent agreement at a 95% confidence level; the planned fluorescence quenching procedure was subsequently utilized to detected the concentration of valsartan in spiked biological fluids and commercial medical tablets.

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Determination of epristeride by its quenching effect on the fluorescence of L -tryptophan

Cited by 13 publications

References 10 publications

Combined Experimental and Computational Study of the In Situ Adsorption of Piroxicam Anions on the Laser-Generated Gold Nanoparticles

Combined Experimental and Computational Study of the In Situ Adsorption of Piroxicam Anions on the Laser-Generated Gold Nanoparticles

Spectroscopic and electrochemical study of interactions between DNA and different salts of 1,4-dihydropyridine AV-153

New Fluorescence Quenching Approach for Determination of Valsartan in Certain Tablets and Spiked Biological Fluids

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