Lipophilicity metabolites

Ahel M, McEvoy J, Giger W (1993) Bioaccumulation of the lipophilic metabolites of nonionic surfactants in fresh-water organisms. Environ Pollut 79 243-248... 

Ahel M, Giger W, Molnar E, Ibric S (2000) Determination of nonylphenol polyethoxylates and their lipophilic metabolites in sewage effluents by normal-phase high-performance liquid chromatography and fluorescence detection. Croat Chem Acta 73 209-227... 

Both hexachloroethane and its lipophilic metabolites can distribute to body fat. Only hexachloroethane can be used to confirm compound exposure by way of a fat biopsy, since some of its metabolites are also produced from other chlorinated hydrocarbons or are present as contaminants in the environment. Based on one worker occupationally exposed to hexachloroethane, Selden et al. (1993) estimated that the plasma half-life in humans was several days, but less than one week. A clearance half-life in rats of 2.5 days was reported for hexachloroethane absorbed from the diet (Gorzinski et al. 1985). Therefore, similar to measurement of hexachloroethane in blood, urine, and feces, hexachloroethane in body fat is representative of current exposures rather than exposures that occurred weeks or months before testing. 

Are Tropical Herbivores More Tolerant of Lipophilic Metabolites Than Are Temperate Herbivores ... 

Is Host Breadth Mediated by Tolerance of Lipophilic Metabolites ... 

Alkylphenol derivatives in the Mediterranean Sea The behaviour of lipophilic metabolites of AgPEO in the Venice lagoon, Italy, was studied in detail by Marcomini et al. [2,3]. Salinity in this estuary is in the range of 25-35%o, and both industrial and domestic wastewater is discharged into the lagoon. Water samples were analysed by high performance liquid chromatography with fluorescence detection (HPLC-FL) [2]. 

The concentrations of both parent surfactant and lipophilic metabolites decreased sharply with increasing distance from the sewage outlet. At a distance of 100 m, the concentrations had all dropped to below 0.5 and 0.1 pg L-1 for A9PEOn and metabolites, respectively. The decrease was mainly explained by an efficient dilution. The concentrations were significantly higher near the water surface, as a consequence of the wastewater plume spreading primarily into the upper freshwater layer, while leaving the saline layer less affected. 

A compound will not necessarily pass all three phases. As will be demonstrated below, a compound may well be transformed into an even more lipophilic metabolite (in contrast to the primary goal of biotransformation). 

The major breakdown products of DDT are DDE and DDD. These products can be further degraded to more hydrophilic compounds like dichlorodiphenylacetic acid (DDA). Stable lipophilic metabolites of p,p -DDE have also been found, such as the phenolic metabolites77 and the ortho- and meta-methylsulfonyl-DDEs. In particular, the latter have been detected in many wildlife species since the 1970s.61 Major breakdown pathways of DDT are depicted in Scheme 4. 

Because it is obvious that primarily the parent drug and lipophilic metabolites are found in hair, some lA are rather specific for single substances of a drug class, e.g., RIA for cocaine (Table 2) or 6-MAM. In both cases, the substance with the highest cross reactivity to the antibody is identical with the main compound excreted into hair after drug consumption. Quantitative immunological results correlate with GC/MS. In the case of the DPC-Kit for free morphine (Table 3), there are good correlations with sensitivity and results of GC/MS and/or HPLC-ECD confirmation. ... 

Although drug metabolism can occur in various body organs including the lungs, GI tract, liver, and kidneys as well as in the blood, the liver is the primary organ for metabolism. Most drugs are metabolized from lipid-soluble parent compounds to more polar, less lipophilic metabolites that are more readily eliminated renally. ... 

Incorporation of xenobiotic acids into lipids forms highly lipophilic metabolites that may burden the body as long retained residues. In the majority of cases, triacylglycerol... 

The synthesis of lipophilic metabolites has been demonstrated in a number of studies of the transformation of xenobiotics, and the following are given as illustration. 

A very different type of reaction is represented by the conjugation of xenobiotic alcohols with fatty acids, yielding highly lipophilic metabolites accumulating in tissues. Thus, ethanol and haloethanols form esters with palmitic acid, oleic acid, linoleic acid, and lin-olenic acid enzymes catalyzing such reactions are cholesteryl ester synthase (EC 3.1.1.13) and fatty-acyl-ethyl-ester synthase (EC 3.1.1.67) (71). Larger xenobiotics such as tet-rahydrocannabinols and codeine are also acy-... 

Lipophilic metabolites tend to accumulate within the production host. If in addition the metabolite is colored or fluorescing, a carotenoid for instance, flow cytometry-based cell sorting protocols are suited to isolate individuals with improved production traits out of a mutagenized population, even if they are present at very low frequency. Value compounds typically produced with B. subtilis production hosts, such as water-soluble vitamins, purine nucleosides, ribose, or proteins, are secreted and accumulate in the culture medium. Screening of improved production strains for such metabolites requires clonal cultivation of the members of the mutagenized population in compartmentalized reactors and individual analyses of the culture supernatants in each of the reactors. 

---