Natural Aromatic Steroids as Potential Molecular Fossils from the Fruiting Bodies of the Ascomycete Daldinia concentrica

The identification of aromatic steroid hydrocarbons bearing a methyl group at positions 1, 2, 3, 4, or 6 in sediments and petroleum has been puzzling since possible steroidal precursors have not yet been reported in living organisms. Two new aromatic steroids, (17β,20R,22E,24R)-19-norergosta-1,3,5,7,9,14,22-heptaene (1) and (17β,20R,22E,24R)-1-methyl-19-norergosta-1,3,5,7,9,14,22-heptaene (2), were isolated from the ascomycete Daldinia concentrica, of which compound 2 bears an unusual methyl group at position 1. We propose that the origin of these compounds is derived from the transformation undergone by their precursor due to microbial action. Compounds 1 and 2 could be the long-sought, biological precursor steroids for organic matter in Earth's subsurface.