PubMed · 14913522
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I KAITO, S TUDA, T NUMASAWA, T NAKAZIMA. 1951-10-25. A new dye (bromphenol-blue) for liver function test.. https://doi.org/10.1620/tjem.54.399
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A simple, rapid, accurate, precise and sensitive colorimetric method for the determination of finasteride in tablets is described. The proposed methods are based on the formation of ion-pair complexes between the examined drug with bromophenol blue (BPB), bromocresol green (BCG) and bromothymol blue (BTB), which can be measured at the optimum lambda(max). Beer's law is obeyed in the concentration ranges 3.0-15.0, 3.0-15.0 and 5.0-20 microg/mL with BPB, BCG and BTB, respectively. The detection limits of FIN was found to be 1.16 microg/mL for BPB, 1.17 for BCG, 1.76 microg/mL for BTB. All the methods gave similar results and were validated for selectivity, linearity, precision and sensitivity. The proposed methods were directly and easily applied to the pharmaceutical preparation with accuracy, resulting from recovery experiments between 100.11 and 100.33% for BPB, 100.17 and 100.67% for BCG and 100.33 and 100.60% for BTB methods. The low relative standard deviation values indicate good precision and high recovery values indicate accuracy of the proposed methods. The proposed methods have been applied to the determination of drug in commercial tablets. Results obtained from the analysis of commercial preparations with the proposed methods are in good agreement with those obtained with the official HPLC method.
Protein chip technology provides a new and useful tool for high-throughput screening of drugs because of its high performance and low sample consumption. In order to screen elastase inhibitors on a large scale, we designed a composite microarray integrating enzyme chip containing chemical arrays on glass slides to screen for enzymatic inhibitors. The composite microarray includes an active proteinase film, screened chemical arrays distributed on the film, and substrate microarrays to demonstrate change of color. The detection principle is that elastase hydrolyzes synthetic colorless substrates and turns them into yellow products. Because yellow is difficult to detect, bromochlorophenol blue (BPB) was added into substrate solutions to facilitate the detection process. After the enzyme had catalyzed reactions for 2 h, effects of samples on enzymatic activity could be determined by detecting color change of the spots. When chemical samples inhibited enzymatic activity, substrates were blue instead of yellow products. If the enzyme retained its activity, the yellow color of the products combined with blue of BPB to make the spots green. Chromogenic differences demonstrated whether chemicals inhibited enzymatic activity or not. In this assay, 11,680 compounds were screened, and two valuable chemical hits were identified, which demonstrates that this assay is effective, sensitive and applicable for high-throughput screening (HTS).
In this study, we have examined the acid-base characteristics of various citrate buffer systems alone and in the presence of the pH indicator dye, bromophenol blue, in aqueous solution, and after lyophilization to produce amorphous material. Fourier transform Raman and solid-state nuclear magnetic resonance spectroscopy have been used to monitor the ratio of ionized to un-ionized citric acid under various conditions, as a function of initial pH in the range of 2.65-4.28. Ultraviolet-visible spectrophotometry was used to probe the extent of proton transfer of bromophenol blue in the citrate buffer systems in solution and the amorphous state. Spectroscopic studies indicated greater ionization of citric acid and bromophenol blue in solution and the solid state with increasing initial solution pH, as expected. Fourier transform Raman measurements indicated the same ratio of ionized to un-ionized citrate species in solution, frozen solution, and the amorphous state. It is shown that the ratio of species at any particular initial pH is primarily determined by the amount of sodium ion present so as to maintain electroneutrality and not necessarily to the fact that pH and pK(a) remain unchanged during freezing and freeze drying. Indeed, for bromophenol blue, the relative ultraviolet-visible intensities for ionized and un-ionized species in the amorphous sample were different from those in solution indicating that the extent of protonation of bromophenol blue was significantly lower in the solid samples. It is concluded that under certain conditions there can be significant differences in the apparent hydrogen activity of molecules in amorphous systems.