Metabolites origin

Although technical chlordane is a mixture of compounds, two metabolites — heptachlor epoxide and oxychlordane — can kill birds when administered through the diet (Blus et al. 1983). These two metabolites originate from biological and physical breakdown of chlordanes in the environment, or from metabolism after ingestion. Heptachlor can result from breakdown of cis- and trans-chlordane, eventually oxidizing to heptachlor epoxide oxychlordane can result from the breakdown of heptachlor, m-chlordane, tra .s-chlordane, or fram-nonachlor (Blus et al. 1983). Heptachlor epoxide has been identified in soil, crops, and aquatic biota, but its presence is usually associated with the use of heptachlor, not technical chlordane — which also contains some heptachlor (NRCC 1975). Various components in technical chlordane may inhibit the formation of heptachlor epoxide or accelerate the decomposition of the epoxide, but the actual mechanisms are unclear (NRCC 1975). 

The principal anabolic pathways for secondary metabolites originate from just a few intermediates of primary metabolic pathways, such as acetyl CoA, shikimic acid, and melvonic acid.86 Among the important cofactors are ATP, NADPH, and S-adenosylmethionine, which need to be continuously regenerated via primary metabolic pathways of respiration or photosynthesis. The fact that secondary metabolism shares chemical precursors with primary metabolism means that secondary and primary metabolic pathways may compete for substrates and cofactors, strongly suggesting that trade-offs occur at the biochemical level. 

The presence of secondary metabolites in organisms has been proposed as an adaptation against predation [56, 57, 58, 59, 60, 61]. Secondary metabolites, toxic or inhibitory to a range of predators, have been isolated from a whole host of different organisms. Secondary metabolites originating from such diverse organisms as dytiscid beetles, (62], tropical seaweeds [63], gorgonians [64. 65] and sea hares [66] have been shown to exhibit anti-predatory properties. 

Indenes and Indenones Indenestrol was identified [69] as a metabolite originating from the use of the very potent estrogen diethylstilbesterol (DES). Fligh transcriptional activity and 10-fold ERp selectivity were observed for the R-enantiomer 39. 

It has been proposed that antibiotics and other secondary metabolites, originally produced by chemical (non-enzymatic) reactions, played important evolutionary roles in effecting and modulating prehistoric reactions (e.g., primitive transcription and translation) by reacting with receptor sites in primi-... 

The residues of the active substances have been investigated with K -labelled active substance. In barley grains a total of 0.05 mg/kg of metabolites originating from ethirimol was detected at harvest, but the ethirimol content was only about... 

A large body of evidence fits well into the present theory. However, on closer inspection many of these examples are evidently of a more complex nature. The phenomena referred to are those where a trait may well have originated in response to external stimuli but where the expression has become of a permanent character independent of the original elicitor. It is conceivable that many of the permanent metabolites originated in this way but proved of such value to the organism that eventually evolutionary selection circumvented the need for a specific environmental elicitor replacing it with some internal cellular transcriptional regulatory system. Some became dependent on some form of internal clock. Such systems often express... 

Appreciation of capillary columns is shown in the most recent papers. As noted by Fitzpatrick [472], many different metabolites originating from arachidonic acid may occur in various samples. Thus, sample complexity appears to be a major deterrent to clarification of the metabolism of prostaglandins and thromboxanes. Impressive chromatograms were shown in glass capillary colunms connected to both the electron capture detector [458,464] and a mass spectrometer [459,469]. Fig. 3.24 seems representative of the recent advances in this area. Moreover, it has been noted [469] that capillary columns may also provide superior quantitation. 

The ochratoxins are a small family of toxic fungal metabolites originally isolated from Aspergillus ochraceus Wilhelm (ref.82). They have subsequently been reported from other Aspergillus species including A. melleus (ref.83,84) and several species of Penicillium (ref. 85-89). Ochratoxins are Icnown to be nephrotoxic and hepatotoxic whilst ochratoxin A is a teratogen (ref.90). Because... 

Tab. 1 Origin, target, and application of commercially important secondary metabolites originating from Actinomycetes [7, 18]...

CJH6N2O2, Mr 138.13, mp. 243-245 °C. A naturally occurring metabolite originating from the degradation of histidine by histidine ammonia lyase (EC 4.3.1.3). It is formed by fermentation, e. g., of Bacillus spp. or by fungi, it is produeed technically by biotransforma-... 

The pyrrole-imidazole alkaloids family comprises hundreds of secondary metabolites originating from marine sponges exclusively. 

Hallucinogenic agents - Several investigators reported the identification and synthesis of active metabolites of (A )-tetrahydrocannabinol (THC). Incubation of the latter with preparations of rat or rabbit liver, yielded 7(ll)-hydroxy-A (A )-THC. Another report described the synthesis of 7-hydroxy-A W THC, an active metabolite, originally isolated from the urine of rabbits . 

Many are the metabolites originated by the PAHs biotransformation. As already exposed, some of these metabolites can be excreted by the organism or even not be reactive to the organisms not conferring, therefore, hazard to the exposed organism. However, many of them, when transformed can cause several alterations in the biological system and put in danger individuals, populations or even entire ecosystems exposed to their action. 

Fig. 10.22 Metabolite origins in 3-hydroxy-3-methylglutaryl-CoA lyase deficiency.

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