Preservation and post-mortem transformations of lipids in samples from a 4000-year-old nubian mummy

Samples of the skin and concretions from inside the thorax and the skull from an ancient Kerma burial were analysed for' extractable carboxylic acids, bile acids and sterols by gas chromatography-mass spectrometry. The results indicate an important reworking of the original biological material by bacteria. The monocarboxylic acids show a bimodal distribution with maxima at C 16/C 18 and C 22/C 24 with significant contributions of odd carbon numbered homologues and iso- and anteiso- acids in the C 15–C 18 range. Unsaturated acids are almost absent. The polar acid fractions are dominated either by the α,ω-dicarboxylic acids in the C 7–C 8 range or by the 9,10dihydroxyalkanoic acids C 18 and C 16. The carbon number distributions of these compounds suggest that they were mainly produced by transformation of unsaturated monocarboxylic acids. In one of the intrathoric samples and in the sample from inside the skull, a homologous series of 4-oxoacides in the C 14–C 15 range, 9- and 10-oxooctadecanoic acids, and a number of positional isomers of monohydroxyhexadecaand octadecanoic acids have also been found as major components for the first time in a natural environment. The carbon number distributions suggest a precursor-product relationship between the oxo- and hydroxyacids and the relative abundances of the positional isomers of the monohydroxyacids designate their source as saturated monocarboxylic acids. Skin and skull samples contained cholesterol as the only sterol while the intrathoracic samples were characterized by the presence of coprostanol with smaller amounts of C 28 and C 29 homologues and lithocholic and deoxycholic acids, indicating a displacement of the intestinal contents toward the thorax.