GC–MS and PCA analyses of diterpenoids degradation state in 21 human mummies of Ancient Egypt dating from New Kingdom to Graeco-Roman Period

Abstract

GC–MS analyses were performed on 25 samples of balms from 21 human mummies, kept in the “musée des Confluences” of Lyon. This study was focused on the diterpenic molecules detected in the organic residues constituting the balms. This chemical family was studied because diterpenoids of Pinaceae resins could be altered due to a number of different chemical reactions, and so they could provide precious information about ageing and/or anthropogenic factors. To obtain greater detail from the results and to illustrate the significance of them, statistical processing and analysis on chromatographic data was applied and has permitted the clear definition of different steps and/or processes of degradation of the abietane type diterpenoid compounds. The statistical results showed that there was a clustering of the samples that correlate with 7-oxo-dehydroabietic and hydroxy-dehydroabietic acids, and another group in correlation with abietic acid. The PC1/PC3 plan gave more information on the state of the samples. Through this plan, 7-oxo-dehydroabietic acid molecules and hydroxy-dehydroabietic acids were positively linked, according to their formation path, contrary to the PC1/PC2 plan. Finally, using PCA, 5 samples were not degraded and they were well conserved in contrast to the 20 other balms. Among these latter balms, 15 of them have been naturally altered by aging and 5 of them have undergone thermal anthropogenic degradation.