Genistein and daidzein are two plant-derived estrogenic compounds. This research explores their environmental fate, focusing on direct and indirect photolysis. We took UV-visible spectra for both compounds at varying pH values, measured the pKa values for both compounds, and determined UV-visible spectra for each protonation state. We observed the loss of both compounds in deionized water exposed to natural sunlight, and determined the quantum yields for each protonation state. In Mississippi River water, direct photolysis does not completely account for the loss of genistein and daidzein. We probed the mechanism of indirect photolysis using quenchers and sensitizers, and suggest that daidzein is transformed mainly via direct photolysis and singlet oxygenation, and genistein is transformed mainly via reaction with triplet-state NOM. The parameters determined in this study will allow estimation of the concentration of genistein and daidzein in sunlit surface waters, and assessment of any risks posed to aquatic wildlife.

Direct and indirect photolysis of the phytoestrogens genistein and daidzein

244th National Meeting (2012)

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