Abstract
A series of novel C
32C
36 polymethylhentriacontenes has been identified in near-surface sediments of the Black Sea. Hydrogenation of these components indicated that they possess the 5,8,14,24,27-pentamethyl-, 8,14,24,27-tetramethyl-, 8,14,24-trimethyl-, 8,14-dimethyl-, and 14- and 15-methylhentriacontane C skeletons, which was confirmed by synthesis of an authentic standard of the C
34 member. The dominant C
36 member of this series contains eight double bonds. The
13C content of these polymethylhentricontenes indicated that they are probably biosynthesized by photoautotrophs and that blooming or bicarbonate pumping affected the
13C content of the fixed C. Their structures suggest that they were biosynthesized by methylation of an unsaturated
n-C
31 precursor at specific positions in a well-defined sequence. This biosynthetic pathway represents an alternative for the biosynthesis of isoprenoid-like components.