Uridine (Urd)

Uridine is a fundamental pyrimidine nucleoside consisting of a uracil molecule attached to a ribose sugar (PubChem CID 6029). It serves as an essential precursor for the synthesis of RNA and is a key intermediate in the pyrimidine salvage pathway, which allows cells to recycle nucleosides when de novo synthesis is impaired (DrugBank DB02721). Beyond its role in genetic material, uridine is vital for the formation of UDP-sugars, such as UDP-glucose, which are necessary for glycogen synthesis and protein glycosylation (NCBI, 2023). While uridine is a naturally occurring metabolite rather than a traditional protein target like a receptor or enzyme, it is utilized therapeutically as an antidote for fluorouracil-induced toxicity and as a replacement therapy for hereditary orotic aciduria (FDA, 2015). In these clinical applications, uridine administration aims to restore nucleotide pools and prevent the incorporation of toxic antimetabolites into cellular RNA (StatPearls, 2023). Additionally, uridine and its nucleotides are involved in extracellular signaling via P2Y receptors, influencing various physiological processes including inflammation and neuroprotection.

Other names

1-beta-D-RibofuranosyluracilUracil ribosideUrd

Uridine acts as a substrate for the pyrimidine salvage pathway, where it is phosphorylated by uridine-cytidine kinase to form UMP, thereby bypassing de novo synthesis blocks (DrugBank DB02721). In cases of fluorouracil toxicity, it competitively inhibits the incorporation of toxic fluorinated nucleotides into RNA, preserving cellular function (FDA, 2015).