Nucleoside

A nucleoside is a molecule composed of a nitrogenous base (purine or pyrimidine) linked to a five-carbon sugar (ribose or deoxyribose)[1][5][7]. Nucleobases, sometimes called nitrogenous bases or nucleotide bases, are the pure base moieties—adenine, guanine, cytosine, thymine, and uracil[3][9]. Nucleosides are precursors for nucleotides, which are essential for the synthesis of DNA and RNA and serve critical roles in cell signaling, energy metabolism, and as molecular drugs. Nucleoside and nucleotide analogues are clinically significant as antiviral and anticancer agents, working through incorporation into nucleic acids or inhibition of polymerase enzymes[7]. The entry "Nucleosides and nucleobases" is too broad for a meaningful target definition as a drug target; individual nucleosides or nucleotide-processing enzymes (e.g., thymidine kinase, ribonucleotide reductase) are the proper entities for therapeutic targeting. Key note: - "Nucleosides and nucleobases" is not a single drug target; it refers to broad molecular classes and should not be classified as a discrete therapeutic target or receptor[7][2]. Specific analogues/drugs act on or mimic individual nucleosides/nucleotides[7]. - For structured drug target databases, specify individual nucleosides (e.g., adenosine), nucleobases (e.g., cytosine), or relevant enzymes (e.g., thymidine kinase) instead.

Other names

NucleosidesNucleobaseNucleobasesNitrogenous baseNucleotide baseNucleosides and nucleobases

Inhibition of DNA/RNA synthesis (chain termination or faulty incorporation); Inhibition of viral DNA polymerase or reverse transcriptase; Interference with nucleotide metabolism