Hydrogenation and Deuterationof Fatty Acid and Phosphatidylcholine

Abstract

A balloon technique was used to hydrogenate a 9-octadecenoic acid (oleic acid) and to deuterate dipalmitoleoylphosphatidylcholine (unsaturated 16:1 DPPC). The hydrogenation of the oleic acid was performed to verify the effectiveness of the balloon technique where deuterium gas was generated in situ in a specially designed twin flask apparatus. Deuteration of unsaturated DPPC was carried out. Deuterium gas is expected to deuterate at the 9, 10 positions of unsaturated DPPC, a 16-carbon acyl chain phospholipid with unsaturation at the 9, 10 positions, converting it into dipalmitoylphosphatidylcholoine with four deuterons (DPPC-d4). Different reaction times were used to find the best reaction time for ideal deuteration. The best reaction time was found to be between 30 - 40 minutes. When the reaction was allowed to run for longer than 40 minutes, overdeuteration occurred at different locations on the molecule. However, with the addition of some H2O, the deuterons exchanged readily with hydrogens to yield DPPC-d4. When the reaction was allowed to run for 15 minutes, deuteration was incomplete. The results were analyzed by proton NMR and deuterium NMR. Thin layer chromatography was used to confirm the findings.