Toxicity homologous series

Two points were tentatively put forward at the time1 to account for this similarity of toxicity. (1) As the homologous series of w-fluoro esters is ascended, the proportion of fluoro-... 

Scala RA, Burtis EG Acute toxicity of a homologous series of branch-chain primary alcohols. Am Ind Hyg Assoc J 34 493 99, 1973... 

The higher alcohols are much more toxic and distasteful. They are very useful as solvents for organic compounds, and as starting points for making compounds in other homologous series. They are certainly not drinkable and many are poisonous. 

In a homologous series of OP compounds, increasing potency for AChE inhibition and cholinergic toxicity correlates with decreasing potency for NTE inhibition and OPIDN. The relative inhibitory potency (RIP) of an OP compound or its active metabolite for NTE versus AChE in vitro can be used as a convenient index of the probable neuropathic potential of the compound. A commonly used measure of inhibitory potency is the IC50, the concentration required to inhibit 50% of the enzyme activity under a standardized set of reaction conditions and time of incubation of the inhibitor with the enzyme preparation. A better measure of inhibitory potency is the bimolecular rate constant of inhibition, ki. When... 

Acute and subchronic toxicity, teratogenicity, and biochemical mechanism studies of a series of structurally similar aliphatic nitriles indicated that although the toxicological profiles were generally the same for most of the compounds, there were unique differences, too (Johannsen and Levinska, 1986). In this respect, acetonitrile was different from the other nitriles within the homologous series. Nitriles liberated cyanide both in vivo and in vitro. Tanii and Hashimoto (1984a,b, 1985) observed a dose-cyanide liberation relationship in liver and hepatic microsomal enzyme system in mice pretreated with carbon tetrachloride. For most nitriles, the toxicity was greatly reduced by carbon tetrachloride pretreatment. By contrast, certain nitriles, exhibited an increase of toxicity as a result of such pretreatment. 

The CoMFA methodology was also used to describe nonlinear lipophilicity-activity relationships, c.g. the inhibitory activities of quaternary alkylbenzyl-dimethylammonium compounds vs. Clostridium welchii (eqs. 206—208) [1025], other antibacterial and hemolytic activities [1026, 1027], and toxic activities of alkanes in mice (eqs. 209-211) [1026] the results of classical QSAR studies (eqs. 206, 207, 209, and 210) [23, 440] were compared with the corresponding CoMFA results (eqs. 208 and 211) [1025-1027] only homologous series of compounds were investigated. 

The degree to which normally nontoxic structures attached to a toxic sulfur atom may influence the molecular toxicity has been studied more systematically (Maxted and Evans, 36) by measuring the relative toxici-ties of a homologous series of alkyl thiols and sulfides in which simple hydrocarbon chains of varying lengths are linked to sulphur, a single chain of this nature being present in the thiols, and two in the sulfide. 

Ethanol, CH3CH2OH, is commonly known as alcohol . It is the second member of the homologous series of primary alcohols highly toxic methanol (CH3OH) is the first. The general formula for the primary alcohols is C H2. 0H. The characteristic part, or functional group, of the alcohols is -OH, called the hydroxyl group. 

QSAR models describing the effects of specific toxicants by mode of action are currently not available for algae. However, for several chemical classes confined models have been derived using substituent constants to rank the effects within homologous series of compounds (Table 5.9). Extrapolation to other substances of the same mode of toxic action is not feasible. 

The relationship of observed toxicity and exposure time is highly dependant on the chemical nature of the compound tested, in agreement with previous observations. For example, studies of the toxicity of aquatic contaminants with the Microtox test showed that the toxicity of some chlorophenols increased with time, while for other compounds of the same homologous series, the opposite trend was found (Ribo and Kaiser 1983). 

Higher molecular weight polyethylene usually shows a low toxicity [2]. The degradation of the molecules results in formation of low molecular weight fragments and even of monomers. The reciprocal dependence of the toxicity of polymers of a certain homologous series on their molecular weight has been reported [2]. 

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