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Photochemistry of Phytoalexins Containing Phenalenone‐like Chromophores: Photophysics and Singlet Oxygen Photosensitizing Properties of the Plant Oxoaporphine Alkaloid Oxoglaucine ¶
Author(s) -
Flors Cristina,
Prat Chantal,
Suau Rafael,
Nájera Francisco,
ll Santi
Publication year - 2005
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.2005.tb01530.x
Subject(s) - singlet oxygen , chemistry , chromophore , photosensitizer , photochemistry , singlet state , alkaloid , oxygen , stereochemistry , organic chemistry , excited state , physics , nuclear physics
Oxoglaucine (OG) is an oxoaporphine alkaloid, which has been linked to plant defense mechanisms. It contains a phenalenone (PN)–like chromophore, which suggests a role as singlet oxygen ( 1 O 2 ) photosensitizer. Indeed, OG is able to photosensitize 1 O 2 with 100% efficiency in nonpolar environments, similar to PN. However, this efficiency decreases in polar and protic media, although 1 O 2 is formed in all environments ranging from benzene to water. OG is a rather inefficient 1 O 2 quencher ( k q = 8 × 10 5 M −1 s −1 ) unlike the related alkaloids boldine and glaucine, for which an antioxidant role has been suggested. The results of this study contribute to the view that plant defense mediated by PN‐like secondary metabolites may have a photochemical component.