Identification of a "pool" of lipid photoproducts in senescent phytoplanktonic cells

The photodegradation of different lipid compounds was studied in killed cel ls of Phaeodactylum tricornutum and Dunaliella sp. Chlorophyll phytyl chain was photodegraded to 6,10,14-trimethyl-pentadecan-2-one and 3-methylidene- 7,11,15-trimethylhexadecan-1,2-diol, sterols to 5 alpha- and 6 alpha/6 beta -hydroxysterols, carotenoids to loliolide and iso-loliolide, and unsaturate d fatty acids to C-7-C-11 omega-oxocarboxylic and alpha,omega-dicarboxylic acids. After elimination of the insufficiently specific photoproducts. 3-me thylidene-7,11,15-trimethyihexadecan-1,2-diol, 5 alpha- and 6 alpha/6 beta- hydroxysterols, C-7-C-11 omega-oxocarboxylic and alpha,omega-dicarboxylic a cids (with C-9 as the most abundant species) were selected to constitute a "pool" of useful indicators of photooxidative alterations of phytoplankton. (C) 1998 Elsevier Science Ltd. All rights reserved.