Heterocyclic compounds toxicity

The importance of the penicillins as a class of heterocyclic compounds derives primarily from their effectiveness in the treatment of bacterial infections in mammals (especially humans). It has been estimated that, in 1980, the worldwide production of antibiotics was 25 000 tons and, of this, approximately 17 000 tons were penicillins (81MI51103). The Food and Drug Administration has estimated that, in 1979 in the U.S.A., 30.1 x 10 prescriptions of penicillin V and 44.3 x 10 prescriptions of ampicillin/amoxicillin were dispensed. This level of usage indicates that, compared to other methods of dealing with bacterial infection, the cost-benefit properties of penicillin therapy are particularly favorable. Stated differently, penicillin treatment leads to the elimination of the pathogen in a relatively high percentage of cases of bacterial infection at a relatively low cost to the patient in terms of toxic reactions and financial resources. 

Quaternary ammonium compounds biocidal activity mechanism, 1, 401 toxicity, 1, 124 Quaternization heterocyclic compounds reviews, 1, 73 ( )-Quebrach amine synthesis, 1, 490 Queen substance synthesis, 1, 439 4, 777 Quercetin occurrence, 3, 878 pentamethyl ether photolysis, 3, 696 photooxidation, 3, 695 Quercetrin hydrolysis, 3, 878 Quinacetol sulfate as fungicide, 2, 514 Quinacridone, 2,9-dimethyl-, 1, 336 Quinacridone pigments, 1, 335-336 Quinacrine... 

The special topics discussed are (i) the biological aspects of heterocyclic compounds, i.e. their biosynthesis, toxicity, metabolism, role in biochemical pathways, and their uses as pharmaceuticals, agrochemicals and veterinary products (ii) the use of heterocyclic compounds in polymers, dyestuffs and pigments, photographic chemicals, semiconductors and additives of various kinds and (iii) the use of heterocyclic compounds as intermediates in the synthesis of non-heterocyclic compounds. 

Benzoxazines are heterocyclic compounds obtained from reaction of phenols, primary amines, and formaldehyde.98,99 As described previously, they are key reaction intermediates in the HMTA-novolac cure reaction.40,43 Crosslinking benzoxazine monomers at high temperatures gives rise to void-free networks with high Tgs, excellent heat resistance, good flame retardance, and low smoke toxicity.100 As in HMTA-cured novolac networks, further structural rearrangement may occur at higher temperatures. 

Licht D, BK Ahring, E Arvin (1996) Effects of electron acceptors, reducing agents, and toxic metabolites on anaerobic degradation of heterocyclic compounds. Biodegradation 1 83-90. 

Unsaturated aliphatic compounds and heterocyclic compounds may also be metabolized via epoxide intermediates as shown in Figure 4.6 and chapter 5, Figure 14. Note that when the epoxide ring opens, the chlorine atom shifts to the adjacent carbon atom (Fig. 4.6). In the case of the furan ipomeanol and vinyl chloride, the epoxide intermediate is thought to be responsible for the toxicity (see below and chap. 7). Other examples of unsaturated aliphatic compounds, which may be toxic and are metabolized via epoxides, are diethylstilboestrol, allylisopropyl acetamide, which destroys cytochrome P-450, sedormid, and secobarbital. 

This section is devoted to brief notes on a structurally disparate range of heterocyclic toxins (Table 6). In most cases only the compound named has been evaluated for toxicity. The general concepts discussed earlier apply to this section, i.e. toxicity has not been distinguished from therapeutic activity, and biological activities should not be assumed to be compound-specific unless appropriate studies have been carried out. The data shown in Table 6 illustrate the range of biological activities shown by at least some heterocyclic compounds and confirm that the possibility of biological activity should not be dismissed for a new heterocycle until appropriate experiments have been conducted. 

Although the toxicity of the vast majority of heterocyclic compounds remains unknown, a few have been studied in detail, usually because a mechanistically interesting or useful toxicity is involved. It would obviously have been inappropriate to devote the whole of this chapter to these agents simply because they have been studied, but consideration at this point of some of them will illustrate many of the general principles discussed earlier — in particular, that toxicity is usually apparent within a family of nominally related chemicals and that the relative activity of individual members may provide information on the physiological or molecular basis of the toxic effect. Sections 1.05.3.6.3-1.05.3.6.5 below are particularly concerned with heterocycles that affect enzyme function. We have selected these firstly because many toxins require enzyme-mediated conversion to an active species, and secondly because many detailed structure-activity studies are available for such agents. 

It is concluded that the study of the toxicity of heterocyclic compounds presents an almost virgin field of scientific endeavor. 

Heterocyclic Compounds with Indole and Carbazole Systems , Interscience, NY(1954), 70-109 17)P.Tavernier M.Lamouroux, MP 39, 355(1957)(Thermochem values) 18)Sax(1957), 435(Toxicity) 19)CondChemDict(l96l), 215 20)... 

Rotenone is the toxic principle of several tropical and subtropical plants, the chief of which is derris. It is a complex organic heterocyclic compound and rotenone derivatives are stomach and contact poisons. 

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