Photochemistry of phytoalexins containing phenalenone-like chromophores: photophysics and singlet oxygen photosensitizing properties of the plant oxoaporphine alkaloid oxoglaucine.
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 x 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.
Flors
Cristina
C
Grup d'Enginyeria Molecular, Institut Químic de Sarrià, Universitat Ramon Llull, 08017 Barcelona, Spain.
Prat
Chantal
C
Suau
Rafael
R
Nájera
Francisco
F
Nonell
Santi
S
D001058:Apomorphine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D043803:Phenalenes / Q000737:chemistry*; D010777:Photochemistry; D017319:Photosensitizing Agents / Q000494:pharmacology*; D026082:Singlet Oxygen / Q000737:chemistry*
D043803:Phenalenes; D017319:Photosensitizing Agents; D026082:Singlet Oxygen; C038036:phenalen-1-one; C111587:oxoglaucine; D001058:Apomorphine