Identification of a novel 7-desmethyl-7-acetonyl bacteriophaeophorbide c series in a recent sediment

We report the identification of three members of a novel 7-desmethyl-7-acetonyl bacteriopheophorbide c series isolated from a coastal salt pond sediment (Salt Pond, MA, USA), as well as the full structure determination (1H NMR) of one of the members. The compounds have the same carbon framework as bacteriopheophorbides c but bear an acetonyl group at C-7. They may be fossils of an unknown photosynthetic pigment series and could be intermediates in the formation of some porphyrins isolated previously from ancient sediments.