Nucléosides

β-Nicotinamide adenine dinucleotide reduced form, most commonly known as NADH, is a cofactor involved in the electron transport chain, in the metabolism of amino acids and many other cellular processes such as the synthesis of ATP. It is also a substrate for glutathione peroxidase and superoxide dismutase. The reduced form of NADH can be used as an indicator for glutathione peroxidase activity. In addition, it has been shown to have antioxidant properties by reducing reactive oxygen species (ROS) and inhibiting lipid peroxidation. This product has been used in formulations of synthetic drugs for the treatment of women with long-term effects of menopause, such as osteoporosis and cardiovascular disease. It has also been used in the production of alginate gel, which can be used to create scaffolds for tissue engineering applications. More recently, in bioorganic chemistry, NADH has been used as a source of hydride species for reduction reactions.

The nucleophilic opening of 2,2'-Anhydrouridine represents a novel synthetic approach for elaborating the ring of nucleosides. For example, compounds such as 2-amino-, 2-fluoro- and 2-phenylseleno-2-deoxyuridines are prepared from the nucleophilic opening of 2,2'-Anhydrouridine.Â2,2'-Anhydrouridine inhibits uridine phosphorylase, a key enzyme targeted by some antitumor drugs.

5-Methylcytidine is a nucleoside that is found in DNA and RNA. It is used in structural biology to probe the structure of DNA. 5-Methylcytidine binds to the enzyme methyl transferase, which catalyzes the transfer of a methyl group from S-adenosylmethionine to produce 5-methyluridine. This reaction occurs in long-term toxicity studies using primary cells, such as lymphocytes and fibroblasts. 5-Methylcytidine has been shown to inhibit tumour growth in mice by binding to nuclear dna polymerase and blocking transcription. The binding site for this drug on the polymerase is located at the same site as that for nucleoside analogues like azidothymidine (AZT) and zidovudine (AZT).