Fundamental to the understanding of human history is the ability to make interpretations based on artefacts and other remains which are used to gather information about an ancient population. Sequestered in the organic matrices of these remains can be information, for example, concerning incidence of disease, genetic defects and diet. Stable isotopic compositions, especially those made on isolates of collagen from bones, have been used to help suggest principal dietary components. A signi¢cant problem in the use of collagen is its long-term stability, and the possibility of isotopic alteration during early diagenesis, or through contaminating condensation reactions. In this study, we suggest that a commonly overlooked material, human hair, may represent an ideal material to be used in addressing human diets of ancient civilizations.Through the analysis of the amino-acid composition of modern hair, as well as samples that were subjected to radiation (thus simulating ageing of the hair) and hair from humans that is up to 5200 years old, we have observed little in the way of chemical change. The principal amino acids observed in all of these samples are essentially identical in relative abundances and content. Dominating the compositions are serine, glutamic acid, threonine, glycine and leucine, respectively accounting for approximately 15%, 17%, 10%, 8% and 8% of the total hydrolysable amino acids. Even minor components (for example, alanine, valine, isoleucine) show similar constancy between the samples of di¡erent ages. This constancy clearly indicates minimal alteration of the amino-acid composition of the hair. Further, it would indicate that hair is well preserved and is amenable to isotopic analysis as a tool for distinguishing sources of nutrition.Based on this observation, we have isotopically characterized modern individuals for whom the diet has been documented. Both stable nitrogen and carbon isotope compositions were assessed, and together provide an indication of trophic status, and principal type (C 3 or C 4 ) of vegetation consumed. True vegans have nitrogen isotope compositions of about 7% whereas humans consuming larger amounts of meat, eggs, or milk are more enriched in the heavy nitrogen isotope. We have also analysed large cross-sections of modern humans from North America and Europe to provide an indication of the variability seen in a population (the supermarket diet). There is a wide diversity in both carbon and nitrogen isotope values based at least partially on the levels of seafood, corn-fed beef and grains in the diets. Following analysis of the ancient hair, we have observed similar trends in certain ancient populations. For example, the Coptics of Egypt (1000 BP) and Chinchorro of Chile (5000^800 BP) have diets of similar diversity to those observed in the modern group but were isotopically in£uenced by local nutritional sources. In other ancient hair (Egyptian Late Middle Kingdom mummies, ca. 4000 BP), we have observed a much more uniform isotopic signature, indicating a more constant...

The analysis of the stable nitrogen isotope compositions of individual amino acid stereoisomers through the use of gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) is presented. Nitrogen isotopic compositions of single amino acids or of their enantiomers is possible without the labor-intensive and time-consuming preparative-scale chromatographic procedures required for conventional stable isotope analysis. Following hydrolysis and derivatization, single-component isotope analysis is accomplished on nanomole quantities of each of the stereoisomers of an amino acid, utilizing the effluent stream of gas chromatographic separation. Nitrogen isotope fractionation is minimal during acylation of the amino acid, with no additional nitrogen being added stoichiometrically to the derivative. Thus, the isotopic composition of the nitrogen in the derivative is that of the original compound. Replicate stable nitrogen isotope analyses of 11 amino acids, and their trifluoroacetyl (TFA)/isopropyl (IP) ester derivatives, determined by both conventional isotope ratio mass spectrometry (IRMS) and GC/C/IRMS, indicate that the GC procedure is highly reproducible (standard deviations typically 0.3-0.4‰) and that isotopic differences between the amino acid and its TFA/IP derivative are, in general, less than 0.5‰.

Establishing the diets of ancient human populations is an integral component of most archaeological studies. Stable isotope analysis of well-preserved bone collagen is the most direct approach for a general assessment of paleodiet. However, this method has been limited by the scarcity of well-preserved skeletal materials for this type of destructive analysis. Hair is preserved in many burials, but is often overlooked as an alternative material for isotopic analysis. Here we report that the stable carbon and nitrogen isotope values for the hair of the 5200 year-old Ice Man indicates a primarily vegetarian diet, in agreement with his dental wear pattern. Whereas previous investigations have focused on bone collagen, the stable isotope composition of hair may prove to be a more reliable proxy for paleodiet reconstruction, particularly when skeletal remains are not well preserved and additional archaeological artifacts are unavailable.

Four new cyclic peptides, patellamide G (2) and ulithiacyclamides E-G (3-5), along with the known patellamides A-C (6-8) and ulithiacyclamide B (9), were isolated from the ascidian Lissoclinum patella collected in Pohnpei, Federated States of Micronesia. The planar structures of these peptides were determined from 1D and 2D 1H and 13C NMR spectra. The absolute stereochemistries of the amino acid units, except for cysteine, were assigned by chiral GC analysis of N(O)-trifluoroacetyl isopropyl ester derivatives of amino acids obtained by acid hydrolysis of the intact and ozonized peptides. The structures of ulithiacyclamides E-G (3-5) were confirmed by chemical conversion. Patellamides B (7) and C (8) exhibited in vitro modulation of multidrug resistance in CEM/VBL100 cells.

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