Remarkable preservation of biomolecules in ancient radish seeds

Desiccated seeds from a 6th century AD storage vessel recovered from Qasr Ibrim, Egypt, were examined for the presence of lipids and nucleic acids. A remarkable degree of lipid preservation was discovered, the fatty acid and sterol profiles being very similar to those of modern radish seeds. The only significant differences were hydrolysis of triacylglycerols and depletion of the polyunsaturated fatty acids (C-18:2 and C-18:3). The delta(13)C values of the principal fatty acids were in the range -25.4 to -29.2 parts per thousand, which is congruent with modern radish (C-3 seeds) taking account of isotopic shifts caused by recent changes in atmospheric CO2. Deoxyribonucleosides and nucleic acid bases were detected by direct chemical analysis, and polymerase chain reactions gave products with sequences comparable to those from modern radish. The degree of lipid preservation, which was much greater than that reported for other archaeological remains, suggests that the microenvironment within desiccated seeds retards biomolecular decay. The results illustrate the utility of combined lipid-nucleic acid analysis in chemotaxonomic and genotypic studies of archaeobotanical remains.