Photo- and Free Radical-Mediated Oxidation of Lipid Components During the Senescence of Phototrophic Organisms

In a first part, visible and UV light-induced photooxidation of the main lipid cell components (chlorophylls, carotenoids, sterols, unsaturated fatty acids, highly branched isoprenoid and linear alkenes, alkenones, cuticular waxes ...) in senescent phototrophic organisms (phytoplankton, cyanobacteria, higher plants, purple sulfur bacteria and aerobic anoxygenic phototrophic bacteria) is examined. Probably due to its long lifetime in hydrophobic micro-environments and thus in senescent cells, singlet oxygen plays a key role in the photodegradation of most of the lipid components.