Susceptibility to peroxidation of the major mycelial lipids of Cunninghamella echinulata

Abstract

AbstractThe distribution of hydroperoxides among lipid fractions (namely neutral lipids, glycolipids, sphingolipids, and phospholipids) of the oleaginous fungus Cunninghamella echinulata was studied during the growth cycle. The lipid hydroperoxide content of total lipids increased during growth. Neutral lipids contained a small amount of hydroperoxides (0.78×10–4–5×10–4 µmol/mg), glycolipids plus sphingolipids contained large amounts of hydroperoxides (14×10–4–17.6×10–4 µmol/mg), while the hydroperoxide content of phospholipids increased greatly during growth (from 4.6×10–4 to 38×10–4 µmol/mg). In addition, the distribution of lipid hydroperoxides among the major phospholipid classes indicated that the neutral phospholipids, namely phosphatidylcholine and phosphatidylethanolamine, were more susceptible to peroxidation than the anionic ones (i.e. phosphatidylinositol and phosphatidylserine). A novel parameter, namely “specific lipid peroxidizability”, which is able to evaluate the susceptibility to peroxidation (peroxidizability) of each lipid fraction/class due to the nature of the lipid itself, was introduced. By using this parameter it was found that peroxidizability depended on the nature of the individual lipid rather than on its polyunsaturated fatty acid content.