The present overview describes the formation of deoxyribonucleic acid (DNA) adducts from endogenous and exogenous aldehydes, such as acetaldehyde, acrolein, crotonaldehyde, malonaldehyde, 4-hydroxy-2-nonenal and 2,4-decadienal. Malonaldehyde reacts with 2’-deoxyguanosine, 2’-deoxyadenosine, and 2’-deoxycytidine, yielding cyclic pyrimidopurinone and acyclic adducts. The direct addition of ɑ,β-unsaturated aldehydes to DNA bases yields cyclic substituted propano adducts, such as 1,N2-propano-2’-deoxyguanosine. Alternatively, ɑ,β-unsaturated aldehydes can be oxidized to reactive epoxides, giving ethano or etheno derivatives upon reaction with DNA. In addition, information on highly sensitive techniques, employed for the in vivo detection and quantification of DNA-aldehyde adducts, is also provided. Some of these DNA-aldehyde lesions have been shown to be highly mutagenic. In fact, lipid peroxidation and exogenous aldehyde exposure could potentially account for the observed carcinogenicity of urban air pollution and cigarette smoke exposure.

The skin is a very complex organ, continuously exposed to physical, chemical and microbiological agents. Enzymes as well as low-molecular weight antioxidants are present in the cutaneous tissue to counterbalance the deleterious effect caused by an oxidative stress and thus maintain homeostasis. Antioxidants such as vitamins C and E, carotenoids, and extracts with these properties have been extensively used for treatment of pathologies and skin aging prevention. We review here different mechanisms that can interfere in the redox equilibrium of the skin, as well as the chemical reactions involved in these processes. Moreover, we discuss the importance of endogenous or exogenous antioxidants that can be acquired from the diet or from oral or topical administration, and methodologies that have been developed to evaluate their efficacy.

The oxidation of sulfite catalyzed by transition metal ions produces reactive oxysulfur species that can damage plasmid and isolated DNA in vitro. Among the four DNA bases, guanine is the most sensitive to one-electron oxidation promoted by the species formed in the autoxidation of sulfite (HSO5-, HO•, SO3•-, SO4•- and SO5•-) due to its low reduction potential and ability to bind transition metal ions capable to catalyze oxidative processes. Some oxidative DNA lesions are promutagenic and oxidative DNA damage is proposed to play a crucial role in certain human pathologies, including cancer.

A number of ring-extended DNA adducts resulting from reaction of alpha,beta-unsaturated aldehydes, or their epoxides, with DNA bases have been characterized in recent years. These adducts can lead to miscoding during DNA replication which, if not repaired, result in mutations that can contribute to cancer development. Recently, the use of ultrasensitive methods allowed the detection of background levels of etheno DNA adducts in tissues of untreated animals and humans suggesting the existence of endogenous sources of reactive intermediates. In this review, we briefly summarize the recent advances in the chemistry of these DNA lesions.

Molecular oxygen, in the first excited state (singlet oxygen, ¹O2), has a substantial reactivity towards electron-rich organic molecules, such as biological targets, including unsaturated fatty acids, proteins, RNA and DNA. Considering the complexity of biological systems and the great variety of reactive species generated by photochemistry, efforts have been devoted to develop suitable ¹O2 generators based on the thermolysis of water soluble naphthalene endoperoxides. These compounds are chemically inert and have been employed as versatile sources of ¹O2. The synthesis is based on structural modifications in position 1,4 of dimethylnaphtalene, grafting hydrophilic substituents. The correspondent endoperoxide can be generated using photochemical method, or molybdate-catalyzed disproportionation of hydrogen peroxide.