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•Fluorescence quenching process has been introduced for the determination of Mirabegron by quenching tyrosine and L-tryptophan fluorophores.•The developed methods were validated as ...per ICH guidelines and the obtained results were statistically analyzed.•Stern-Volmer relationship was studied at different temperatures for the quenching mechanism recognition which is static or dynamic.•The double log plots were constructed to evaluate binding sites and binding constants.•Greenness of the proposed methods has been assessed to clarify the extent of environmental safety.
Green spectrofluorimetric methods have been adopted for the determination of Mirabegron (MG) in pure drug and pharmaceutical dosage form. The developed methods based on fluorescence quenching of tyrosine and L-tryptophan amino acids fluorophores by the effect of Mirabegron as a quencher. Experimental conditions of the reaction were studied and optimized. The Fluorescence quenching (ΔF) values were proportional to the concentration range of MG 2–20 μg/ml for the tyrosine-MG system in buffered media pH 2 and 1–30 μg/ml for L-tryptophan-MG system pH 6. Good correlation coefficients with low detection limits of 0.163 and 0.234 μg/ml for the two systems respectively. Method validation was applied according to ICH guidelines. The cited methods were successively applied for MG determination in tablet formulation. No statistically significant difference between the results of the cited and the reference methods regarding t and F tests. The proposed spectrofluorimetric methods are simple, rapid, eco-friendly and can contribute to MG’s methodologies in quality control labs. Stern-Volmer relationship, the effect of temperature, quenching constant (Kq), and UV spectra were studied to identify the mechanism by which the quenching might occur. The results demonstrated that fluorescence quenching of tyrosine was a dynamic quenching process and L-tryptophan was static. The double log plots were constructed to determine the binding constants and binding sites. The greenness profile of the developed methods has been assessed by Green Analytical procedure index (GAPI) and Analytical Greenness Metric Approach (AGREE).
Apixaban and Tirofiban Hydrochloride are low molecular weight anticoagulants. The two drugs exhibit native fluorescence that allow the development of simple and valid spectrofluorimetric methods for ...the determination of Apixaban at λ ex/λ em=284/450nm and tirofiban HCl at λ ex/λ em=227/300nm in aqueous media. Different experimental parameters affecting fluorescence intensities were carefully studied and optimized. The fluorescence intensity-concentration plots were linear over the ranges of 0.2–6μgml−1 for apixaban and 0.2–5μgml−1 for tirofiban HCl. The limits of detection were 0.017 and 0.019μgml−1 and quantification limits were 0.057 and 0.066μgml−1 for apixaban and tirofiban HCl, respectively. The fluorescence quantum yield of apixaban and tirofiban were calculated with values of 0.43 and 0.49. Method validation was evaluated for linearity, specificity, accuracy, precision and robustness as per ICH guidelines. The proposed spectrofluorimetric methods were successfully applied for the determination of apixaban in Eliquis tablets and tirofiban HCl in Aggrastat intravenous infusion. Tolerance ratio was tested to study the effect of foreign interferences from dosage forms excipients. Using Student's t and F tests, revealed no statistically difference between the developed spectrofluorimetric methods and the comparison methods regarding the accuracy and precision, so can be contributed to the analysis of apixaban and tirofiban HCl in QC laboratories as an alternative method.
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•New validated spectrofluorimetric methods for the analysis of selected anticoagulants.•The developed methods are successfully applied for the analysis of selected drugs in drug substances and drug products.•The methods are based on the measurements of the native fluorescence of selected drugs.•The proposed methods can be used as alternative methods in quality control laboratories.
ABSTRACT Tirofiban hydrochloride was subjected to the degradation under conditions of hydrolysis (acidic and alkaline degradation), oxidative, thermal and photolytic degradation as prescribed by ICH. ...A simple and precise liquid chromatographic method has been developed and validated for the simultaneous determination of tirofiban hydrochloride monohydrate (TIR) and its synthetic starting material; tyrosine (TRS). All the chromatographic separations were achieved on Zorbax SB C18, 250 mm×4.6 mm i.d., 5μm column at a flow rate of 1 mL min–1. Isocratic elution based on 0.1 M phosphate buffer (pH 3) - acetonitrile (70:30, v/v) with UV detection at 227 nm was applied. For the stability study separation of TIR from its degradation products was achieved using 0.1 M phosphate buffer (pH 3) - acetonitrile (72:28, v/v) with UV detection at 210 nm. Method validation parameters namely, linearity, accuracy and precision were found to be acceptable over the concentration ranges of 10-250 μg mL–1 for TIR and 1-70 μg mL–1 for TRS. The minimum detection limits were 1.76 μg mL–1 for TIR and 0.13 μg mL–1 for TRS. The optimized method was validated and proved to be specific, robust and accurate for the quality control of the cited drug in drug substance and drug product.
Deregulation of stem cells is associated with the generation and progression of malignant tumors. In addition, genes that are associated with early embryogenesis are frequently expressed in cancer. ...Cripto-1 (CR-1), a glycosylphosphatidylinositol-linked glycoprotein, is expressed during early embryogenesis and in various human carcinomas. We demonstrated that human embryonal carcinoma (EC) cells are heterogeneous for CR-1 expression and consist of two distinct subpopulations: a CR-1(High) and a CR-1(Low) population. By segregating CR-1(High) and CR-1(Low) populations of NTERA2/D1 EC cells by fluorescence-activated cell sorting, we demonstrated that CR-1(High) cells were more tumorigenic than CR-1(Low) cells by an in vitro tumor sphere assay and by in vivo xenograft formation. The CR-1(High) population was enriched in mRNA expression for the pluripotent embryonic stem (ES) cell genes Oct4, Sox2, and Nanog. CR-1 expression in NTERA2/D1 cells was regulated by a Smad2/3-dependent autocrine loop, by the ES cell-related transcription factors Oct4/Nanog, and partially by the DNA methylation status of the promoter region. These results demonstrate that CR-1 expression is enriched in an undifferentiated, tumorigenic subpopulation and is regulated by key regulators of pluripotent stem cells.
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