Metabolite analogues water

Steroid hormones form a group of pollutants that includes natural hormones such as estradiol, testosterone, and their metabolites as well as several synthetic analogues. Steroid hormones used as growth promoters have already been found in water and sediments (Lai et al. 2000 Thorpe et al. 2003), and their adsorption properties on earth materials have been considered. Lee et al. (2003) report batch experiments where simultaneous sorption of three hormones (17- 3-estradiol, 17-a-ethyl estradiol, and testosterone) on four midwestem U.S. soils and a freshwater sediment were performed. Apparent sorption equilibria were reached within a few hours. Sorption isotherms generally were linear for the chemicals studied on one of these soils (Drummer soil), ranged from 23.4 to 83.2 L kg and log ranged... 

Recently, a CIO carba analogue (TDR 40292) 70 has been compared with artemether . This compound cannot form DHA as a metabolite and contains a side-chain that can be formulated as a water-soluble salt. In addition, this compound has superior activity to artemether and artesunate, both in vitro and in vivo. From initial pharmacokinetic data, 70 has a higher volume of distribution than artemether and is considerably more orally bioavailable (16% versus 1.5% for artemether) . 

Ishida et al. (1995) hrst described a new water-soluble polyether BTX analogue (Bl) isolated from New Zealand cockles (Austrovenus stuchburyi). BTX-Bl is the taurine conjugate of PbTx-2 and was the predominant BTX metabolite produced within the cockle. BTX-Bl was not ichthyo-toxic. It was only found in low levels in Greenshell mussels (Perna canaliculus) and not at all in Pacihc oysters (Crassostrea gigas). PbTx-3 was found in all three species (Nozawa et al., 2003) and parent PbTx-2 in Cr. gigas (Ishida et al., 1996). 

Now we come to consider the most remarkable relationship ever encountered between a metabolite and its antagonistic analogue. The position occupied on the enzyme by methotrexate, as described above, is the reverse of that occupied by dihydrofolate, of which the Californian workers supply the following details (Bolin et al., 1982). N-1 is unbound, 2-NH2 is bound only to water, as is 0-4. N-3 is bound by a hydrogen bond to Asp-26, N-5 is unbound, and N-8 has a van der Waals bond to Leu-4. Thus, compared to methotrexate, the normal substrate is very loosely bound, at least as regards the pteridine ring. The/ -aminobenzoic and glutamic portions, however, are identically bound in both metabolite and... 

Commonly used drugs, dietary constituents and food additives may be electroactive and consequently are potential sources of interference when biological samples are analysed. Quinine may originate from tonic water, for example, caffeine from coffee and cafifeinated soft drinks and some proprietary stimulants, nicotine and cotinine from tobacco smoke, chloroquine and related compounds from malaria prophylaxis, and pholcodine and other opiate analogues from cold cures. Many such compounds and their metabolites will show an EC response at carbon electrodes under appropriate conditions and can be sources of confusion if unrecognised. 

Anfossi, L. et al, Development of a non-competitive immunoassay for monitoring DDT, its metabolites and analogues in water samples. Anal. Chim. Acta, 506, 87,2004. 

Another SPR-based immunosensor for DDT, its metabolites, and analogues in real water samples was developed by Mauriz et al. Low limits of detection (LODs), in the sub-nanogram per liter range, were attained for DDT-selective (15 ng 1 ) and DDT group-selective immunoassays (31 ng 1 ). The SPR analysis of DDT proved to be three times more sensitive than colorimetric ELlSAs without the need of labeling combined with a much shorter time of respmise. This SPR biosensor portable platform (P-SPR) is also commercialized by the SENSIA company. 

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