Metabolite , generally characterization

Most often chiral metabolites are characterized by optical activity because of their origin in enzyme mediated reaction sequences. In fact, this rule is of such generality that the first example of a marine secondary metabolite of low enantiomeric purity (8-9) appeared as recently as in 1984. 

Organochlorine pesticides have been detected in samples of fat tissues. However, endrin was not found in adipose tissue samples of the general population (Stanley 1986 Williams et al. 1988). In pesticide manufacturing workers, endrin was found in the adipose tissue only after very high exposures. Endrin has been detected in the milk of lactating women (0.02-6.24 mg/kg milk fat) (Alawi et al. 1992 Bordet et al. 1993). In conclusion, the quantitation of endrin exposure, via parent compound or metabolite, remains difficult at best. Further studies characterizing the pharmacokinetics of endrin are needed. 

The National Institutes of Health (NIH) has characterized "[t]he general aim of metabolomics. .. to identify, measure and interpret the complex, time-related concentration, activity and flux of endogenous metabolites in cells, tissues and other biosamples such as blood, urine and saliva."3 Taken together, the three "omics" disciplines represent a systemic and powerful approach to mapping cellular networks, allowing for faster and more predictive biology in terms of risk assessment, potential therapeutic benefit, as well as diagnosis. 

Antibiotics are generally defined as low molecular mass microbial secondary metabolites which, at low concentrations, inhibit the growth of other microorganisms. To date, well in excess of 10 000 antibiotic substances have been isolated and characterized. Overall, antibiotics are a chemically heterogeneous group of molecules, although (as described later) many can be classified into different families based upon similarity of chemical structure. 

Phytochemical studies of these species led to the isolation and structural characterization, by NMR and MS analysis, of many secondary metabolites, mainly flavonoids, and expecially flavonol glycosides, clerodane diterpenes, and triterpenes having the lupane, ursane, and oleanane skeletons. Particularly flavonoids and their glycosides have a chemotaxonomic interest in the genus and in general in the Chrysobalanaceae family. 

In a general sense, the kinetics and metabolism of toluene in humans, rats and mice are very similar the hippurate is in all cases by far the major metabolite, while in all species the ortho- and / ora-cresols are minor metabolites. To what extent formation of a potentially reactive sulfate conjugate of benzyl alcohol occurs (van Doom et al., 1980 Chidgley et al., 1986) is uncertain, mainly because mercapturates formed from toluene have not been characterized. Similarly, whether the covalent binding observed in rat liver microsomes has any toxicological relevance is uncertain. 

---