Photochemical oxidation and autoxidation of chlorophyll phytyl side chain in senescent phytoplanktonic cells: potential sources of several acyclic isoprenoid compounds in the marine environment.
Visible light-induced degradation of the chlorophyll phytyl side chain was studied in senescent cells of two phytoplanktonic strains (Skeletonema costatum and Thalassiosira weissflogii). Particular attention was paid to the induction of autoxidation processes on the phytyl chain and its photoproducts by photochemically produced hydroperoxides. The combination of photochemical oxidation and autoxidation reactions resulted in the production of several acyclic isoprenoid compounds that have been unambiguously identified by comparison of their retention times and mass spectra with those of appropriate standards. Various mechanisms are proposed to explain the formation of these oxidation products. These processes appear to be potential sources of numerous oxidized acyclic isoprenoids that previously have been detected in lacustrine and marine environments. Some oxidation products newly described or whose presence in natural samples was never reported in the literature were then sought in particulate matter, sediment, and microbial mat samples. The results obtained supported the significance of photochemical oxidation and autoxidation of phytoplanktonic chlorophyll phytyl side chain in the marine environment.
Rontani
Jean-François
JF
Laboratoire d'Océanographie et de Biogéochimie (UMR 6535), Centre d'Océanologie de Marseille, 13288 Marseille, France. rontani@com.univ-mrs.fr
Rabourdin
Adélaïde
A
Marchand
Daphné
D
Aubert
Claude
C
D016922:Cellular Senescence; D002734:Chlorophyll / Q000737:chemistry / Q000378:metabolism*; D017377:Diatoms; D019015:Geologic Sediments; D019563:Mechanics; D010084:Oxidation-Reduction; D010777:Photochemistry; D010839:Phytoplankton / Q000166:cytology / Q000378:metabolism*; D013729:Terpenes / Q000378:metabolism
D013729:Terpenes; D002734:Chlorophyll