Hydrocarbons carcinogenic benzenoid

Balasubramanian, K., Kaufmann, J.J., Koski, W.S. and Balaban, A.T. (1980). Graph Theoretical Characterization and Computer Generation of Certain Carcinogenic Benzenoid Hydrocarbons and Identification of Bay Regions. J.Comput.Chem., 1,149-157. 

Graph theoretical characterization and computer generation of certain carcinogenic benzenoid hydrocarbons and identification of bay regions were reported by K. Balasubramanian, J. J. Kaufman, and W. S. Kosky in 1980, almost 35 years ago [28]. 

A tetracyclic benzenoid hydrocarbon suspected of being a carcinogen. 

Scheme 8. Mechanism of carcinogenic activity of benzenoid hydrocarbons...

Most of the more previous attempts to correlate carcinogenic potency with structural features of benzenoid hydrocarbons are related to the mechanism outlined above. The different quantitative models that have been developed can be distinguished with regard to the number of independent variables. One-variable theories (e.g. the so-called bay-region theory [94]) are normally inferior compared to two- [95] and three-variable theories which refer more explicitely to the different and partly competing metabolic reaction pathways. A particularely efficient model has been developed by v. Szentpaly [96]. In his so-called MCS model three important influences on carcinogenic potency are taken into account M, the initial epoxidation... 

Herndon, W.C. and Szentpaly, L.V. (1986) Theoretical model of activation of carcinogenic polycyclic benzenoid aromatic hydrocarbons. Possible new classes of carcinogenic aromatic hydrocarbons. 

Like benzene, all the larger polycyclic benzenoid hydrocarbons undergo electrophilic substitution reactions. Some of these compounds are well-known carcinogens. The chemical reactions responsible for causing cancer and how you can predict which compounds are carcinogenic were discussed in Section 12.8. 

Aromatic benzenoid hydrocarbons are important raw materials for the chemical industry, allowing the manufacture of plastics, fibers, strong textiles and a large variety of other products. However, aromatic benzenoid hydrocarbons as such do not have many uses, especially since some of them (benzene, benzanthracene, benzopyrene) are proved carcinogens. One of the few uses involves a mixture of meta- and / ara-terphenyl which has such a high thermal and radiolytical stability that it can be used as moderator and heat transfer fluid in organic-moderator ... 

Our book, being about solved and unsolved problans in structural chentistry, induced us to select carcinogenicity as a property of benzenoid hydrocarbons to illustrate considerable variations of some of the properties of this group of compounds because there are several issues that have not been clarified and understood concerning benzenoids and their carcinogenicity. Consider a question, which we consider to be unsolved ... 

What are, if any, the structural factors that may answer why some benzenoids do not follow the regularity that holds for most benzenoid hydrocarbons that associates the presence of the bay regions with carcinogenicity ... 

A topic closely related to enumeration and construction of benzenoid hydrocarbons is enumeration and construction constrained by specific structural requirements. An example is enumeration of benzenoid hydrocarbons having a bay region. According to Jerina and co-workers, " the presence of a bay region is critical for the carcinogenic activity of benzenoid hydrocarbons. Let us first define a bay region, following Balasubramanian et al. ... 

A large number and variety of demonstrated carcinogens, including haloalkanes, quinones, benzenoid, and polynuclear aromatic hydrocarbons, aromatic nitro compounds, aromatic amines, metals, as well as other organic and inorganic compounds have been shown to fit these criteriaJ31l... 

A large number of polycyclic benzenoid aromatic hydrocarbons are known. Many have been synthesized in the laboratory, and several of the others are products of combustion. Benzo[a]pyrene, for example, is present in tobacco smoke, contaminates food cooked on barbecue grills, and collects in the soot of chimneys. Benzo[a]pyrene is a carcinogen (a cancer-causing substance). It is converted in the liver to an epoxy diol that can induce mutations leading to the uncontrolled growth of certain cells. 

These ideas were applied for comparing aliphatic alcohols, carcinogenic polycyclic benzenoid aromatic hydrocarbons, and binding constants between human corticosteroid binding globulin and a set of 47 steroids. The last set of compounds was also investigated by comparative molecular field analysis (CoMFA) with comparable results. A similar approach was used by Klopman and Raychaudhury on the basis of the Wiswesser Line Notation system. 

Polynuclear aromatics are hydrocarbons containing more than one fused benzenoid ring. These substances primarily occur in coal, coal tar, heavy oil, diesel fnel and many petroleum products. They are also found in soils, sediments, solid wastes, many wastewaters, emission from indnstrial boilers and tobacco smoke at trace concentrations. In the PAH class, U.S. EPA has hsted 16 compounds as priority pollutants in potable water and wastewater and 22 componnds in soil and solid wastes. Except naphthalene most PAH compounds have little commercial applications. However, they may be generated from various sources or industrial operations the exposure to which may pose risk to human health. Many PAHs may cause cancers, affecting a variety of tissues. However, only benzo[a]pyrene is a potent human carcinogen, while naphthalene, benzo[a]anthracene. 

FIGURE 14.14 Benzenoid aromatic hydrocarbons. Some poiycyciic aromatic hydrocarbons (PAHs), such as dibenzo[a,/]pyrene, are carcinogenic. (See important, but hidden, epoxides at the end of Chapter 11.)... 

A large number of polycyclic benzenoid aromatic hydrocarbons are known. One of these, benz[tobacco smoke. From the literature, locate and then draw the structure of this hydrocarbon. Can you suggest other sources where this material might be expected to be present ... 

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