BACCHARANE (18,19-SECOLUPANE) - A RARE TRITERPENOID SKELETON WIDESPREAD IN TRIASSIC SEDIMENTS AND PETROLEUM FROM THE ADRIATIC BASIN

Baccharane (18,19-secolupane) 1, a triterpenoid skeleton seldom encoun tered in living organisms, has been characterized together with 17beta H-des-E-lupane 2, one of its minor degradation products, in Italian Tr iassic sediment and crude oil samples from the Adriatic Basin by synth esis of standards. Reports of baccharane-derived triterpenoids in the field of natural products are scant and up to now restricted to terres trial plants (angiosperms and ferns). In this regard, sedimentary bacc harane derivatives may indicate a continental contribution (ferns?) to fossil organic matter; but they may also represent a contribution of as yet undetermined marine microorganisms, as has been proposed for da mmarenes and dammaranes. Alternatively, they could be the bio/geochemi cal transformation products of biosynthetically closely related precur sors such as lupane- or dammarane-type triterpenoids. The apparently r estricted occurrence of baccharane derivatives in geological samples ( up to now detected only in Triassic sediments of the Adriatic Basin) c onfers upon these compounds great value as correlation parameters and possibly as source indicators.