Branched chain fatty acids in phospholipids of guinea pig Harderian gland

Fatty acid compositions of phosphatidyl ethanolamine and phosphatidyl choline extracted from the guinea pig Harderian gland were examined by gas chromatography and gas chromatography-mass spectrometry. Oleic acid was the major component of both phospholipids, but a large amount of saturated branched chain fatty acids was found: 34.5% in phosphatidyl ethanolamine, and 42.9% in phosphatidyl choline. On the other hand, linolenic and arachidonic acids were not found in these phospholipids. At the 1-position of phosphatidyl choline and phosphatidyl ethanolamine, 54.3% and 40.9% of fatty acids, respectively, had methyl branches. These methyl branches were located at the even-numbered carbon atoms. Branched chain fatty acids were also found at the 2-position of both lipids: 36.2% in phosphatidyl choline and 31.2% in phosphatidyl ethanolamine. The fatty acids of phosphatidyl ethanolamine and phosphatidyl choline from liver, cerebrum, cerebellum, erythrocytes, and plasma of the same animal were also analyzed. Saturated and unsaturated fatty acids, including arachidonic acid, were the major components. Branched chain fatty acids were also found in these lipids, but in very small amounts.