Structural determination of purpurin-18 (as methyl ester) from sedimentary organic matter

We report the isolation and structural determination (RP-18 HPLC, UV–VIS, MS, 1H NMR and two-dimensional 1H NMR (COSY and ROESY)) of purpurin-18 (as methyl ester) from geological samples. Existing data suggest that purpurins-18 are derived from chlorophyll or its transformation products by postdepositional, microbially mediated processes in sediments. Diagenetic transformations of purpurins-18 can lead through fossilization to pyrroporphyrins and some ETIO porphyrins isolated from sediments.