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Characterizing some photophysical, photochemical and photobiological properties of photosensitizing anthraquinones

Paper ID Volume ID Publish Year Pages File Format Full-Text
28395 44074 2007 7 PDF Available
Title
Characterizing some photophysical, photochemical and photobiological properties of photosensitizing anthraquinones
Abstract

Some photophysical, photochemical and photobiological properties of nine anthraquinones (AQs) isolated from a phototoxic plant, Heterophyllaea pustulata, were studied. The photosensitized generation of superoxide anion radical (O2−) and singlet molecular oxygen (1O2) by three of the nine AQs, namely heterophylline, pustuline and 5,5′-bisoranjidiol was evaluated. Whereas the O2− production (Type I photosensitization mechanism) was examined in vitro using human leukocyte suspensions and measuring the reduction of NBT, the 1O2 generation (Type II photosensitization mechanism) was studied in an organic solvent through the measurement of the quantum yield of 1O2 (ϕΔ). It was established that these three AQs possess photosensitizing properties as do the other AQ derivatives present in this vegetable species, soranjidiol, soranjidiol 1-methyl ether, rubiadin, rubiadin 1-methyl ether, damnacanthal and damnacanthol, acting both by Type I and Type II mechanisms. Furthermore, nordamnacanthal, a species synthesized in the laboratory from one of the natural AQs, showed the highest production of 1O2.The ability of natural AQs to deactivate the 1O2 generated during the photosensitization process as well as their fluorescence (as competitive mechanisms to the generation of ROS) was studied.

Keywords
AQs, anthraquinones; 3O2, molecular oxygen; 1O2, singlet molecular oxygen; O2−, superoxide anion radical; NBT, nitroblue tetrazolium; UV, ultraviolet; UVR, UV radiation; kr, reactive rate constant for 1O2 quenching; kq, physical rate constant for 1O2 quen
First Page Preview
Characterizing some photophysical, photochemical and photobiological properties of photosensitizing anthraquinones
Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 188, Issues 2–3, 20 May 2007, Pages 185–191
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering