Novel carotenol chlorin esters in marine sediments and water column particulate matter

Novel esters of carotenols and chlorins (carotenol chlorin esters, CCEs) we re found in recent sediments from the California Borderlands, Monterey Bay, and the Peru and Oman margins. The chlorins associated with CCEs were pheo phorbide a and pyropheophorbide a, degradation products of chlorophyll a. I sofucoxanthin-dehydrate and isofucoxanthinol-dehydrate and possibly their i somers, degradation products of fucoxanthin, were the only carotenols assoc iated with CCEs. This result is surprising, considering that at least 8 maj or degradation products of fucoxanthin are present in organic-rich marine s ediments. The carotenols of CCEs are likely derived from diatoms as these a re the primary source for fucoxanthin in the marine environment. In sedimen ts studied by us, CCEs contributed approximately 10% to total solvent extra ctable chlorins. The high relative concentrations of CCEs in these sediment s suggest that CCEs are an important degradation product of chlorophyll a i n some marine environments; a pathway hitherto unrecognized. Off Oman and S outhern California we found CCEs in water column suspended particulate matt er when diatoms dominated the phytoplankton community. By analogy with ster ol chlorin esters, we suggest that CCEs are primarily produced by enzymatic ally mediated transesterifications in crustaceans grazing on diatoms. We ar e currently studying if CCEs are biomarkers for the grazing of crustaceans on diatoms, an important pathway of carbon remineralization in the marine e nvironment. (C) 1999 Elsevier Science Ltd.