Photoprotection and the Photophysics of Acylated Anthocyanins


Autoria(s): Silva, Palmira Ferreira da; Paulo, Luisa; Barbafina, Adrianna; Eisei, Fausto; Quina, Frank Herbert; Macanita, Antonio L.
Contribuinte(s)

UNIVERSIDADE DE SÃO PAULO

Data(s)

07/11/2013

07/11/2013

2012

Resumo

The proposed role of anthocyanins in protecting plants against excess solar radiation is consistent with the occurrence of ultrafast (525 ps) excited-state proton transfer as the major de-excitation pathway of these molecules. However, because natural anthocyanins absorb mainly in the visible region of the spectra, with only a narrow absorption band in the UV-B region, this highly efficient deactivation mechanism would essentially only protect the plant from visible light. On the other hand, ground-state charge-transfer complexes of anthocyanins with naturally occurring electron-donor co-pigments, such as hydroxylated flavones, flavonoids, and hydroxycinnamic or benzoic acids, do exhibit high UV-B absorptivities that complement that of the anthocyanins. In this work, we report a comparative study of the photophysics of the naturally occurring anthocyanin cyanin, intermolecular cyanincoumaric acid complexes, and an acylated anthocyanin, that is, cyanin with a pendant coumaric ester co-pigment. Both inter- and intramolecular anthocyaninco-pigment complexes are shown to have ultrafast energy dissipation pathways comparable to those of model flavylium cationco-pigment complexes. However, from the standpoint of photoprotection, the results indicate that the covalent attachment of co-pigment molecules to the anthocyanin represents a much more efficient strategy by providing the plant with significant UV-B absorption capacity and at the same time coupling this absorption to efficient energy dissipation pathways (ultrafast internal conversion of the complexed form and fast energy transfer from the excited co-pigment to the anthocyanin followed by adiabatic proton transfer) that avoid net photochemical damage.

Fundacao para a Ciencia e Tecnologia (FCT), Portugal

Fundacao para a Ciencia e Tecnologia (FCT), Portugal [YPTDC/QUI/65728/2006]

Ministero per lUniversita e la Ricerca Scientifica e Tecnologica of Rome, Italy

Ministero per l'Universita e la Ricerca Scientifica e Tecnologica of Rome, Italy

University of Perugia [20088NTBKR]

University of Perugia

Fondazione Cassa di Risparmio di Perugia

Fondazione Cassa di Risparmio di Perugia

Identificador

CHEMISTRY-A EUROPEAN JOURNAL, WEINHEIM, v. 18, n. 12, p. 3736-3744, MAR, 2012

0947-6539

http://www.producao.usp.br/handle/BDPI/42990

10.1002/chem.201102247

http://dx.doi.org/10.1002/chem.201102247

Idioma(s)

eng

Publicador

WILEY-V C H VERLAG GMBH

WEINHEIM

Relação

CHEMISTRY-A EUROPEAN JOURNAL

Direitos

closedAccess

Copyright WILEY-V C H VERLAG GMBH

Palavras-Chave #PHOTOCHEMISTRY #PHOTOPHYSICS #PLANT CHEMISTRY #REACTION MECHANISMS #UV #VIS SPECTROSCOPY #STATE PROTON-TRANSFER #FLUORESCENCE LIFETIMES #MALVIDIN 3-GLUCOSIDE #VEGETATIVE TISSUES #FLAVYLIUM SALTS #BIOLOGICAL ROLE #GROUND-STATE #LEAVES #PROTECTION #HYDRATION #CHEMISTRY, MULTIDISCIPLINARY
Tipo

article

original article

publishedVersion