13²,17³-Cyclopheophorbide b enol as a catabolite of chlorophyll b in phycophagy by protists

Abstract

Both 13(2),17(3)-cyclopheophorbide a and b enols were produced along with ingestion of green microalgae containing chlorophylls a and b by a centrohelid protist (phycophagy). The results suggest that chlorophyll b as well as chlorophyll a were directly degraded to colored yet non-phototoxic catabolites in the protistan phycophagic process. Such a simple process by the predators makes a contrast to the much sophisticated chlorophyll degradation process of land plants and some algae, where phototoxicity of chlorophylls was cancelled through the multiple enzymatic steps resulting in colorless and non-phototoxic catabolites.

Keywords: (13(2)R)- and (13(2)S)-hydroxychlorophyllones; (R/S)-hCPLs; 13(2),17(3)-cyclopheophorbide a enol; 13(2),17(3)-cyclopheophorbide b enol; APCI; Aquatic ecosystem; Chl; Chlorophyll catabolism; Cyclopheophorbide enol; Microalga; PAO; PDA; PPB; Phe; Phycophagy; Protist; TOF; atmospheric pressure chemical ionization; cPPB-aE; cPPB-bE; chlorophyll; pPPB; pPhe; pheophorbide; pheophorbide a oxygenase; pheophytin; photodiode array; pyropheophorbide; pyropheophytin; time-of-flight.