Biomarkers lipids

Pathways of carbon flow in natural environments have also been reconstracted using bulk stable carbon and nitrogen isotopes as well as compound-specific isotopic analysis of individual biomarker lipid component (Hayes et al, 1990) based on the fractionations involved during primary (photosynthetic) and secondary (heterotrophic) processes. Recently, compound-specific radiocarbon analysis of individual biomarker hpid has been shown to be a valuable technique to determine the source of marine organic matter (Eglinton et al., 1997). 

LUCAS E A, WILD R D, HAMMOND L J, KHALIL D A, JUMA S, DAGGY B P, STOECKER B J and ARJMANDI B H (2002) Flaxseed improves lipid profile without altering biomarkers of bone metabolism in postmenopausal women. J Clin Endocrinol Metab. 87 (4) 1527-32. 

Recent findings from the ATBC stndy even showed that P-carotene snpple-mentation increased the post-trial risk of a hrst-ever non-fatal MI. Two secondary prevention trials, the Heart Protection Stndy and the ATBC presented similar resnlts. The former showed no association between P-carotene and fatal or non-fatal vascular events and the latter reported signihcantly increased risks of fatal coronary events in the P-carotene-snpplemented gronp. Resnlts of clinical trials focused on the effects of carotenoids on CVD biomarkers are controversial. Although carotenoid supplementation increased sernm levels,only lycopene was shown to be inversely associated with lipid, protein, DNA and LDL oxidation, and plasma cholesterol levels. - - ... 

Results obtained in in vivo and ex vivo experiments are of various types. Some studies have found positive effects of the consumption of carotenoids or foods containing carotenoids on the markers of in vivo oxidative stress, even in smokers. Other studies demonstrated no effects of carotenoid ingestion on oxidative stress biomarkers of lipid peroxidation. " It should be noted that for studies using food, the activity observed may also be partly due to other antioxidant molecules in the food (phenols, antioxidant vitamins) or to the combination of actions of all the antioxidants in the food. 

Microbes of differing physiologic types, acting in consortia, appear to be more destructive than monocultures. Methods for examining consortia are based on the detection of lipid biomarkers that are characteristic for different classes of microbes. These can be analyzed by gas chromatography coupled with mass spectrometry [512]. 

Quinones, lipid-soluble substances involved in electron transport, can also be used as biomarkers. Lipski et al. (155) u.sed quinone analyses, physiological tests, and fatty acid profiles to differentiate Gram-negative non-fermentative bacteria isolated from biofilters. Quinone type was found to be an efficient method to group isolates prior to the analysis of results from the physiological tests. The detection of quinones appears to be restricted to the discrimination of isolated colonies and has limited potential to the analysis of mixed populations. 

The introduction of fast-atom bombardment (FAB) half a decade later extended the analyst s biomarker repertoire to intact polar lipids, desorbed... 

A number of polypeptide biomarkers have also been identified in the mass range below 4000,28-31 which are cyclic secondary metabolites bonded to lipids or sugars. These peptide sequences are not directly translated from DNA,32... 

Nevertheless, there are some vegetable oils that have a very specific composition. For example, castor oil consists of large amounts (83 89%) of 12-hydroxy-(Z)-9-octadecenoic acid (ricinoleic acid) which is not found in other natural lipids [21]. Ricinoleic acid produces a very characteristic oxidation product, 9,12-dihydroxyoctadecanoic acid [43], and both of these compounds can be considered as specific biomarkers for castor oil and have been used to assess its presence in ceramic lamps [43] and mummification balms [23]. 

In the present chapter, we first provide some general information concerning the chemistry of waxes and lipids currently encountered in various items from our cultural heritage and we detail the main protocols based on direct mass spectrometry that have been developed so far. We then discuss the mass spectra obtained by EI-MS on a range of reference substances and materials sampled from museum and archaeological artefacts. We then focus on the recent possibilities supplied by electrospray ionisation for the elucidation of the structure of biomarkers of beeswax and animal fats. 

Hence, direct mass spectrometry techniques, either using El or ESI, appear to be powerful and innovative analytical tools for elucidating the structure of the main biomarkers present in a wide range of waxes and lipids that may be preserved in archaeological objects and in museum works of art. In most cases, they have nevertheless to be cautiously exploited in combination with other complementary analytical techniques. 

Only a few specific kinds of lipids can be identified on the basis of the characteristic features of the FA profile and the presence of specific biomarkers. For example, oils obtained from the seeds of Brassicaceae, such as rapeseed oil, are characterized by abundant amounts of uncommon FA such as gondoic (Z-11 -eicosenoic) acid and erucic (Z-13-docosenoic) acid and, after ageing their oxidation products. Other examples are reported in Table 7.2 and in Chapter 1. 

Table 7.2 Some examples of lipid chemical features and molecular biomarkers that have been used to highlight lipid sources in archaeological organic residues...

Simpson LA., van Bergen P.F., Perret V., Elhmmali M.M., Roberts D.J., Evershed R.P., Lipid biomarkers of manuring practice in relict anthropogenic soils, The Holocene, 1999, 9, 223 229. 

Corr, L. T., Richards, M. P., Jim, S., Ambrose, S. H., Mackie, A., Beattie, O. and Evershed, R. P. (2008) Probing dietary change of the Kwad y Dan Ts inchj individual, an ancient glacier body from British Columbia I. Complementary use of marine lipid biomarker and carbon... 

Sauer, P. E., Eglinton, T. I., Hayes, J. M., Schimmelmann, A. and Sessions, A. L. (2001) Compound specific D/H ratios of lipid biomarkers from sediments as a proxy for environmental and climatic conditions. Geochimica et Cosmochimica Acta 65, 213 222. 

---