Conversion of Alcohol to Ethyl Esters of Fatty Acids by the Lactating Goat

Abstract

FRESHLY secreted milk contains a lipogenic principle that will incorporate fatty acids into the ester lipids of the milk¹. While investigating this principle with the aid of palmitic-l-¹⁴C acid and thin-layer chromatographic analysis of the resulting labelled lipids, we noted a prominent spot on autoradiograms between the solvent front and the position of the triglycerides (Fig. 1). The position of this unknown substance was very close (following) to that of the cholesterol esters. It occurred to us that this spot might result from ethyl palmitate-l-¹⁴C, since the labelled compound was dissolved in ethanol (usually 250 µl.) to facilitate dispersion in the milk. Further investigation confirmed this contention. The radioactive unknown substance exhibited R_F values similar to authentic ethyl palmitate with three different thin-layer chromatographic solvent systems. When the area of a plate containing the unknown was extracted and this extract injected on to an appropriate gas chromatographic column, 45 per cent of the activity measured in the unknown spot was trapped during the time ethyl palmitate would have emerged from the column. Since this recovery value results, in part, from losses in the syringe, in the column, by detector leaks, etc., the major activity is concluded to have moved in correspondence with ethyl palmitate.