Biological action toxic

On the basis of biological action, toxic substances may, for example, act as ... 

Technology Description Hydrolysis is the process of breaking a bond in a molecule (which is ordinarily not water-soluble) so that it will go into ionic solution with water. Hydrolysis can be achieved by the addition of chemicals (e.g., acid hydrolysis), by irradiation (e.g., photolysis) or by biological action (e.g., enzymatic bond cleavage). The cloven molecule can then be further treated by other means to reduce toxicity. 

Bioavailability is defined as the portion or fraction of a chemical that is available for biological action and is influenced by several factors including the molecular size and charge of a molecule, structural features of membranes, first pass metabolism, and therefore, bio availability can be influenced by the molecular structure of a chemical. This situation presents an opportunity for molecular designers to manipulate a chemical s structure to decrease bioavailability and consequently hazard. If the availability of a molecule can be decreased, the amount of chemical at the site of action is decreased which leads to decreased toxicity. 

Where a substance causes concern as a result of some specific aspects of its biological action (e.g. a therapeutic class of which several members have produced positive oncogenic results), its pattern of toxicity or long-term retention (of drug or metabolites) detected in previous studies positive findings in genotoxicity studies. 

Some chemicals, such as strong aids and bases, exert their toxic action in a nonspecific way simply by denaturing protein and dissolving the tissue. Such lesions are referred to as chemical bums. In most cases, however, toxins act by interacting with specific components of the tissue, thus perturbing normal metabolism. Early in the twentieth century Paul Ehrlich proposed the concept of specific receptors (Ehrlich, 1913). He postulated that a chemical, in order to exert biological action, must reach a specific target area and fit into a receptor site. 

If the combination of a high-resolution separation system with a physicochemical detection principle is specific to properties of many harmful (toxic) chemicals, then a straightforward approach may be possible (27). Electron capture detection (ECD) registers electronegative compounds. Since the early 1960s, Lovelock (28) has pointed at the possible link between the ability of a substance to capture electrons and its biological action. 

The 2-hydroxybenzoic acid, normally called salicylic acid, is well known due to its medical applications, namely as an antipyretic and in the treatment of certain types of rheumatism. The biological action of this compound is connected4,5 with its ability to bind metal ions. Not only is the efficacy of the treatment increased, but toxicity problems related to the injection of salicylic acid are diminished by administering salicylate metal complexes. 

Data on the biological actions of dipyridothiophenes are scarce. Information is lacking in the review (1987KFZ536), where considerable attention was given to the pharmacological aspect of the use of thienopyridine derivatives. The anticonvulsive activity of substituted pyrido[3,2, 4,5]thieno[3,2-6]pyridine, which has low toxicity, was documented (1996RFP1417446). 

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