Aerobic and anaerobic abiotic oxidation of squalene in the presence of hydroperoxides

Abiotic oxidation of squalene in the presence of hydroperoxysterols was studied in seawater under aerobic and anaerobic conditions. This ubiquitous isoprenoid alkene is quickly degraded in the presence of oxygen and its oxidation results mainly in the production of tertiary alcohols and to a lesser extent of epoxides and secondary alcohols. Although the degradation of squalene logically slows down under anaerobic conditions, a significant oxidation affording similar products than in the case of aerobic degradation has been observed. These results show that hydroperoxysterols, which seem to be well preserved in Recent sediments, could contribute to the oxidation of unsaturated lipids (such as squalene) in sedimentary environments under oxic and anoxic conditions.