Journal of Lipid Research, Vol. 8, 342-349, July 1967
Copyright © 1967 by Lipid Research, Inc.

Properties and metabolism of 2-alkylalkanoates. III: Absorption of methyl and ethyl 2-methylpalmitate

Thomas A. Saladin and Edward A. Napier Jr.

Gastroenterology Research Laboratories, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan

The recovery from rat and rabbit tissues of fed methyl-¹⁴C and ethyl-2-¹⁴C 2-methylpalmitate with unaltered specific activity has demonstrated the existence of mechanisms for the absorption and deposition of both methyl and ethyl esters of fatty acids, at least for 2-methylpalmitate. In thoracic duct-cannulated rats, approximately 9% of the fed compounds was recovered from the lymph during the first 24 hr, the rate of recovery reaching a maximum between 6 and 8 hr. In the rabbit, the fed, unaltered esters in plasma were transported principally by means of the low density lipoproteins.

Only trace amounts of the unaltered esters were subsequently detected in the blood and tissue lipids after feeding, however, even during the period of maximal absorption; moreover, in contrast to at least one report by others, further analyses for methyl or ethyl esters of other fatty acids has shown that such esters of short-chain alcohols constitute no more than a trace amount (0.004-1.03%) of the lipids extracted from a wide variety of mammalian tissues. The possibility remains that even these trace amounts of esters arose as artifacts of autolysis, extraction, or assay.

Supplementary key words methyl • ethyl • esters • 2-methylpalmitate • absorption • occurrence • transport • lipoproteins • gas-liquid chromatography

Submitted on August 9, 1966
Accepted on March 9, 1967

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