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Scientific article
English

A new series of steryl chlorin esters: Pheophorbide a steryl esters in an oxic surface sediment

Published inOrganic geochemistry, vol. 31, no. 12, p. 1703-1712
Publication date2000
Abstract

Investigation of chlorins in the oxic surface sediment of a small eutrophic alpine lake (Motte lake) revealed the presence of a new series of steryl chlorin esters containing the pheophorbide a nucleus, together with their pyropheophorbide a steryl ester counterparts previously observed in the anoxic surface sediment of the same lake. Identification of the pheophorbide a steryl esters was based on comparison of spectroscopic, chromatographic and mass spectrometric characteristics of the compounds with those of a synthetic standard and of pyropheophorbide a steryl esters. Combined liquid chromatography-mass spectrometry analysis confirmed the absence of pheophorbide a steryl esters in the anoxic sediment but allowed their detection in traces in the water column, indicating that pheophorbide a steryl esters are, like their pyropheophorbide a analogs, formed in the water column. The distribution of sterols released by hydrolysis of the pheophorbide a steryl esters shows close similarities to that of the free sterols in the water column and of the sterols of the pyropheophorbide a steryl esters. It appears that, like their pyropheophorbide a counterparts, pheophorbide a steryl esters incorporate mainly sterols of phytoplanktonic origin. Their formation probably involves the same mechanism as for pyropheophorbide a steryl ester formation, i.e. metabolism by zooplankton grazing on phytoplankton. The presence of pheophorbide a steryl esters in the oxic sediment and their absence from the anoxic sediment is probably due to a lower stability of compounds containing a carbomethoxy substituent in the anoxic environment.

Keywords
  • Steryl chlorin esters
  • Sterols
  • Pheophorbide a
  • Pyropheophorbide a
  • Sediments
  • LC–MS
Research group
Citation (ISO format)
RIFFÉ-CHALARD, Catherine, VERZEGNASSI, Ludovica, GULACAR, Fazil. A new series of steryl chlorin esters: Pheophorbide a steryl esters in an oxic surface sediment. In: Organic geochemistry, 2000, vol. 31, n° 12, p. 1703–1712. doi: 10.1016/S0146-6380(00)00072-3

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