Browsing by Subject "estrogenic activity"

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  • Le, Thanh Ngoc Uyen (Helsingin yliopisto, 2017)
    The aims of this study were to use the heterologously expressed laccase in Pichia pastoris as oxidative biocatalysts for the degradation of BPA and to find out natural mediators that could assist this laccase to degrade BPA efficiently and environmental friendly. In addition, removal of the estrogenic activity of BPA by the white rot fungus Physisporinus rivulosus cultures and the role of its laccase 2 in the BPA disapperance was also focused. Firstly, the removal of BPA’s estrogenic activity by the white rot fungus Physisporinus rivulosus was confirmed in cultures both with and without the fungal mycelium. Next, the recombinant laccase 2 (rLac2) played a role in the BPA disapperance. At the similar laccase activity level, removal of BPA’s estrogenic activity was done more efficiently in the fungal cultures than in the cell-free enzymatic treatments. Metabolites present in the fungal cultures could possibly act as natural mediators that enhance the removal of BPA. In addition, combination of nine laccases present in the fungal cultures could possibibly enhance the degradation of BPA. Finally, none of the ten mediatiors used was found to act as an efficient rLac2 enhancer in degrading BPA. Degradation of BPA was followed using a bioreporter system. The yeast Saccharomyces cerevisiae has been genetically modified in order to express the estrogen receptor alpha and produce a bioluminescent signal upon contact with estrogenic substances such as BPA. This bioreporter system has been further developed to specifically detect the estrogenic activity of bisphenol A and to be used in a high-throughput manner.
  • Omoruyi, Iyekhoetin Matthew; Ahamioje, Derek; Pohjanvirta, Raimo (2014)
  • Omoruyi, I.M.; Pohjanvirta, R. (2018)
    Mounting evidence of the effects of endocrine-disrupting chemicals (EDCs) in humans has led to assaying a vast array of food items (processed or packaged) as possible sources of human exposure to estrogens. In this study, we investigated the current situation in this respect of different food supplements and beer brands. Eleven food supplements and 24 beer brands were obtained from Helsinki, Finland. Sample preparation was carried out by established methods while estrogenic activities were assessed by a yeast bioluminescent assay, using two recombinant yeast strains (Saccharomyces cerevisiae BMAEREluc/ERα and S. cerevisiae BMA64/luc). All the food supplements as well as 81% of the beer samples tested were found to be estrogenic, with estradiol equivalent concentrations of food supplements and beer brands ranging from 7.5 to 11.5 µg/ml and from below detection limits to 43.6 ng/ml, respectively. The estrogenic activities detected in beer samples were not dependent on the beer's alcoholic content, the country of production, or the size of the production brewery. The results of our study imply that both food supplements and beers can be a significant source of human exposure to estrogens. Therefore, further studies and regular surveillance are warranted. © 2018, © 2018 Taylor & Francis Group, LLC.