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Dunford CL, Smith GJ, Swinny EE, et al. The fluorescence and photostabilities of naturally occurring isoflavones. Photochem Photobiol Sci. 2003;2(5):611-5doi: 10.1039/b300078h.
Dunford, C. L., Smith, G. J., Swinny, E. E., & Markham, K. R. (2003). The fluorescence and photostabilities of naturally occurring isoflavones. Photochemical & photobiological sciences : Official journal of the European Photochemistry Association and the European Society for Photobiology, 2(5), 611-5. https://doi.org/10.1039/b300078h
Dunford, Cara L, et al. "The fluorescence and photostabilities of naturally occurring isoflavones." Photochemical & photobiological sciences : Official journal of the European Photochemistry Association and the European Society for Photobiology vol. 2,5 (2003): 611-5. doi: https://doi.org/10.1039/b300078h
Dunford CL, Smith GJ, Swinny EE, Markham KR. The fluorescence and photostabilities of naturally occurring isoflavones. Photochem Photobiol Sci. 2003 May;2(5):611-5. doi: 10.1039/b300078h. PMID: 12803086.
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Photochem Photobiol Sci. 2003 May;2(5):611-5. doi: 10.1039/b300078h.

The fluorescence and photostabilities of naturally occurring isoflavones.

Photochemical & photobiological sciences : Official journal of the European Photochemistry Association and the European Society for Photobiology

Cara L Dunford, Gerald J Smith, Ewald E Swinny, Kenneth R Markham

Affiliations

  1. New Zealand Institute for Industrial Research, P.O. Box 31310, Lower Hutt, New Zealand.

PMID: 12803086 DOI: 10.1039/b300078h

Abstract

The 5,7-dihydroxyisoflavones do not emit detectable fluorescence and are significantly more photostable than the two 7-hydroxy-5-deoxyisoflavones, daidzein and formononetin. The latter isoflavones emit fluorescence that depends on the basicity of the solution and the polarity of the solvent. Comparison of the spectral distributions of the emission in methanol in the presence and absence of base indicates that it originates from the conjugate anion excited singlet states. The fluorescence of daidzein and formononetin exhibit large Stokes shifts to longer wavelengths in methanol, ethanol, hexanol and acetonitrile and the magnitudes of these shifts increase with solvent polarity. This indicates that the emission originates from excited singlet states with much larger dipole moments than those of the corresponding ground states. Values of 8.3 D and 6.5 D were determined for daidzein and formononetin respectively. The photostabilities of formononetin and daidzein both increase with increasing solvent polarity and in corresponding solvents, the photostability of daidzein is higher than that of formononetin, behaviour which is attributed to the greater antioxidant activity of daidzein.

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