Classification Term: 170072

Cytosine deoxyribonucleoside

C9H13N3O4 (227.0906)

1-[4-hydroxy-5-(hydroxymethyl)oxolan-2-yl]-4-imino-1,4-dihydropyrimidin-2-ol belongs to the class of organic compounds known as pyrimidine 2'-deoxyribonucleosides. Pyrimidine 2'-deoxyribonucleosides are compounds consisting of a pyrimidine linked to a ribose which lacks a hydroxyl group at position 2. 1-[4-hydroxy-5-(hydroxymethyl)oxolan-2-yl]-4-imino-1,4-dihydropyrimidin-2-ol is an extremely weak basic (essentially neutral) compound (based on its pKa). This compound has been identified in human blood as reported by (PMID: 31557052 ). Cytosine deoxyribonucleoside is not a naturally occurring metabolite and is only found in those individuals exposed to this compound or its derivatives. Technically Cytosine deoxyribonucleoside is part of the human exposome. The exposome can be defined as the collection of all the exposures of an individual in a lifetime and how those exposures relate to health. An individual's exposure begins before birth and includes insults from environmental and occupational sources. Cytosine deoxyribonucleoside, commonly referred to as deoxycytidine, is a nucleoside consisting of deoxyribose (a sugar) and cytosine (a nitrogenous base). It is an essential component of DNA and plays several critical roles in biological systems. Here is a detailed description of its biological functions: DNA Synthesis: Deoxycytidine is a key building block for the synthesis of DNA. During DNA replication, deoxycytidine is incorporated into the growing DNA strand as deoxycytidine monophosphate (dCMP), which is then converted to deoxycytidine triphosphate (dCTP) by cellular kinases. dCTP serves as a substrate for DNA polymerase, which adds deoxycytidine to the nascent DNA strand according to the base-pairing rule (cytosine pairs with guanine). DNA Repair: Deoxycytidine is involved in the DNA repair process. When DNA is damaged by environmental factors or errors during replication, repair mechanisms such as base excision repair, nucleotide excision repair, and mismatch repair utilize deoxycytidine to correct the lesions and restore the DNA to its original sequence. Genetic Coding: As part of the DNA molecule, deoxycytidine contributes to the genetic code. The sequence of nucleotides, including deoxycytidine, in DNA determines the sequence of amino acids in proteins, which ultimately dictates the structure and function of proteins and, consequently, the phenotype of the organism. Gene Expression: Deoxycytidine is also involved in gene expression. The presence of cytosine in specific sequences can lead to the formation of methyl groups (DNA methylation), which can regulate gene expression by either promoting or repressing the transcription of genes. Antiviral and Anticancer Therapy: Deoxycytidine analogs, such as cytarabine (ara-C) and zidovudine (AZT), are used in antiviral and anticancer therapies. These analogs can be incorporated into the viral or cancer cell DNA, leading to chain termination or other disruptions in DNA synthesis and function. Cellular Metabolism: Deoxycytidine can be phosphorylated to form deoxycytidine monophosphate (dCMP), deoxycytidine diphosphate (dCDP), and deoxycytidine triphosphate (dCTP). These phosphorylated forms are intermediates in the metabolic pathways of nucleotide synthesis and can be used for energy transfer within the cell. Nucleotide Pool Homeostasis: Deoxycytidine is part of the deoxynucleotide pool within the cell. Maintaining a balance of deoxynucleotides is crucial for various cellular processes, including DNA synthesis, repair, and regulation of gene expression. Enzymes such as nucleotide kinases, nucleotide phosphatases, and nucleoside transporters help regulate the levels of deoxycytidine and its phosphorylated forms.