DELTA-2-TRITERPENES - EARLY INTERMEDIATES IN THE DIAGENESIS OF TERRIGENOUS TRITERPENOIDS

A series of DELTA-2-triterpenoids (oleana-2,12-diene, oleana-2,13(18)-diene, oleana-2,18-diene, ursa-2,12-diene, and taraxera-2,14-diene) has been identified in Holocene buried mangrove sediments (Florida, USA) by comparison of the mass spectra of and by co-injections with authentic standards. In the Oligocene Brandon lignite (Vermont, USA) oleana-2,12-diene and oleana-2,13(18)diene were also identified, along with two A-ring contracted amyrin derivatives. By comparison with the sedimentary occurrence of related analogues of oxyallobetulin and betulin and the demonstrated diagenetic formation of lup-2-ene from lupan-3-one, these novel terrigenous biological markers are considered diagenetic products formed by dehydration of precursor molecules, such as alpha and beta-amyrin, and taraxerol. The identification of these early intermediates brings us one step closer to the full understanding of the diagenetic fate of terrigenous triterpenoids.