Synthesis and mutagenicity of some cyclopenta[c]phenanthrenes and indeno[c]phenanthrenes

Cyclopenta[c]phenanthrenes--chemistry and biological activity

Despite cyclopenta-fused polycyclic aromatic hydrocarbons (CP-PAHs) having been detected in the environment, the ability of these compounds to induce cellular and tissue responses remains poorly characterized. In this review, we look at the chemistry and biological activity of the cyclopenta[c]phenanthrenes (CP[c]Phs) as potential chemicals of concern in the process of risk assessment. The first part of the review deals with the environmental occurrence and chemistry of CP-PAHs, focusing on available methods of CP[c]Ph chemical synthesis. The most interesting structural feature of the CP[c]Ph is the presence of a pseudo fjord-region constructed by the cyclopentane ring. This compound can be treated either as a structurally similar one to B[c]Ph, or as a phenanthrene skeleton with an electrodonating alkyl substituent in the bay-region of the molecule. The second thread, providing available data on the adverse effects of CP[c]Ph compounds on cells and tissues of living organisms, mainly fish, improves our understanding of these possible environmental hazards. The data show that CP[c]Ph is less potent at inducing CYP1A gene expression in rainbow trout than benzo[a]pyrene (B[a]P), a well-known Ah-receptor agonist. Interestingly, the CP[c]Ph dependent up-regulation of CYP1A mRNA is positively correlated with the incidences of clastogenic changes in rainbow trout erythrocytes. CP[c]Ph has, comparably to B[a]P, a potential to repress expression of tumor suppressor p53, in the head kidney of rainbow trout. Furthermore, estrogen responsive genes in fish liver, ERα and VTG, are not induced by CP[c]Ph, suggesting that the compound has no endocrine disrupting potential. However, some CP[c]Phs show mutagenic activity when investigated in the Ames test, and exhibit genotoxic properties in in vitro micronucleus assay. The above characteristics suggest that CP-PAHs are chemicals of concern for which potential pathways of exposure should be further identified.

Influence of structural and functional modifications of selected genotoxic carcinogens on metabolism and mutagenicity - a review

Alterations in molecular structure are responsible for the differential biological response(s) of a chemical inside a biosystem. Structural and functional parameters that govern a chemical's metabolic course and determine its ultimate outcome in terms of mutagenic/carcinogenic potential are extensively reviewed here. A large number of environmentally-significant organic chemicals are addressed under one or more broadly classified groups each representing one or more characteristic structural feature. Numerous examples are cited to illustrate the influence of key structural and functional parameters on the metabolism and DNA adduction properties of different chemicals. It is hoped that, in the event of limited experimental data on a chemical's bioactivity, such knowledge of the likely roles played by key molecular features should provide preliminary information regarding its bioactivation, detoxification and/or mutagenic potential and aid the process of screening and prioritising chemicals for further testing.

Quantitative structure-activity relationship modeling of polycyclic aromatic hydrocarbon mutagenicity by classification methods based on holistic theoretical molecular descriptors

Various polycyclic aromatic hydrocarbons (PAHs), ubiquitous environmental pollutants, are recognized mutagens and carcinogens. A homogeneous set of mutagenicity data (TA98 and TA100,+S9) for 32 benzocyclopentaphenanthrenes/chrysenes was modeled by the quantitative structure-activity relationship classification methods k-nearest neighbor and classification and regression tree, using theoretical holistic molecular descriptors. Genetic algorithm provided the selection of the best subset of variables for modeling mutagenicity. The models were validated by leave-one-out and leave-50%-out approaches and have good performance, with sensitivity and specificity ranges of 90-100%. Mutagenicity assessment for these PAHs requires only a few theoretical descriptors of their molecular structure.

Synthesis and structure--mutagenicity relationship of benzo-annulated cyclopentaphenanthrenes

The synthesis of 2,3-dihydro-1H-indeno[5,4-a]anthracene (2), the fluoreno[a]anthracenes 3 and 4, 2,3-dihydro-1H-cyclopenta[a]chrysene (6), 3,4-dihydro-2-vinylphenanthrene (10) and cyclopenta[c]chrysenes 11, 12 has been described. Structure analysis of the new products by (1)H and (13)C NMR spectroscopy is presented. Estimates of the mutagenic activity of compounds 2--4, 6 and 11--14 in Salmonella typhimurium determined by Ames' test indicate that all products are inactive for both TA 98 and TA 100 strains except 4,5-dihydro-3H-cyclopenta[c]chrysene (12). The mutagenic properties of these compounds have been compared with those shown by previously studied benzo[g]cyclopenta[a]phenanthrenes and cyclopenta[c]phenanthrenes and discussed. Some conclusions have been drawn about the effects of benzoannulation and of the carbonyl function on the mutagenicity of this class of compounds.