Properties and metabolism of 2alkylalkanoates. 3. absorption of methyl and ethyl 2-methylpalmitate.

The recovery from rat and rabbit tissues of fed methyl-(14)C and ethyl-2-(14)C 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.