PubMed · 16512046
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Furosemide.. https://pubmed.ncbi.nlm.nih.gov/16512046/
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Front-face fluorescence spectroscopy was used for the first time to study the interactions between bovine beta-lactoglobulin variant A (beta-Lg A) and various beta-Lg-derived bioactive peptides. Fluorescence spectra were recorded for beta-Lg A-peptide mixtures at 25 degrees C and pH 6.8 with an excitation wavelength of 290 nm to characterize the molecular environment of tryptophan (Trp) residues present in the protein but absent in the peptides. Spectra remained unchanged following addition of peptides beta-Lg f92-100 and beta-Lg f125-135, while Phe-Phe interaction between beta-Lg f69-83 molecules interfered with analysis. Addition of beta-Lg f102-105 produced a blue shift (3 nm) and a significant increase in fluorescence intensity, while addition of beta-Lg f142-148 also caused a significant increase in fluorescence intensity but accompanied by a red shift (3 nm). These results indicate that the polarity of the Trp environment in the beta-Lg A structure may be modified differently depending on the peptide added.
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Pharmaceuticals enter aquatic environments in unchanged form or as metabolites. Little is known about their potential hormonal activity, which is of particular interest due to potential long-term effects on fertility and reproduction in aquatic organisms. Moreover, there is a need to assess the combined activity of pharmaceutical mixtures. In this study, 37 pharmaceuticals have been analysed in vitro for estrogenic activity using a recombinant yeast system expressing the human estrogen receptor alpha. Six pharmaceuticals belonging to different therapeutic classes, cimetidine, fenofibrate, furosemide, paracetamol, phenazone and tamoxifen, exhibited weak estrogenic activity. Furosemide showed an almost full concentration-response curve, whereas the other compounds showed low efficacy. The half-maximal activities of the pharmaceuticals were in the range of 0.66-25.53 mM. Furthermore, binary mixtures of furosemide and 17beta-estradiol (E2), and furosemide and phenazone, and mixtures of up to five active pharmaceuticals were assessed for their combinatory activity at different equipotent concentrations. The estrogenic activity of binary mixtures of furosemide with E2 and phenazone, respectively, followed the model of concentration addition (CA). Mixtures of other pharmaceuticals often deviated from the CA model, because extrapolations become inaccurate with only partial and non-parallel concentration-response curves having low efficacy. This demonstrates that full and parallel concentration-response curves are a prerequisite for accurate predictions of mixture activity. Our study demonstrates for the first time weak estrogenic activity in vitro of some common pharmaceuticals and their mixtures.