Inevitable generation of primary alcohols during reduction of oxidized lipids with sodium borohydride.

This report deals with the fluorometric determination of fatty alcohols generated by the reduction of the ester linkage of lipids with NaBH4, and with the limitations of the reduction method for assaying oxidized lipids. Optimum conditions for the fluorometric analysis of primary and secondary alcohols using 1-anthroyl nitrile were obtained. After reduction with NaBH4 in MeOH or in MeOH/benzene (8∶2, v/v), the formation of 1-hexadecanol from a variety of palmitic acid esters was measured fluorometrically by reverse-phase high-performance liquid chromatography (HPLC): From glycerides and methyl palmitate, 1-3% (w/w) 1-hexadecanol was produced and a trace was produced from cholesteryl palmitate (10 min, 21°C). 1-Hexadecanol was never generated from palmitic acid. Although considerable improvement occurred with the choice of the solvent for the NaBH4 reduction, the generation of primary alcohols from ester lipids usually seems inevitable.