Polymethylsqualanes from Botryococcus braunii in lacustrine sediments and crude oils

A novel hydrocarbon 3,7,18,22-tetramethylsqualane has been identified in extracts from the Maniguin-2 well on Maniguin Island, Philippines, the Duri oil from Sumatra, Indonesia and the Maoming Oil Shale from China. A related hydrocarbon, tentatively assigned the structure 3,7,11,14-tetramethylsqualane, occurs in the Maniguin samples. Like C34 botryococcane, the tetramethylsqualanes are unusually enriched in 13C compared to co-occuring n-alkanes and C16–20 acyclic isoprenoids. Polymethylsqualanes extend the range of distinctive hydrocarbons produced by Botryococcus braunii and its fossil counterparts.