uridine

Uridine is widely produced in nature as uridine monophosphate (uridylate) by de novo synthesis by the decarboxylation of orotidylate, which is catalyzed by orotidylate decarboxylase. The orotidylate is produced from orotate, which is combined with 5-phosphoribosyl-1-pyrophosphate (PRPP) to form orotidylate by pyrimidine phosphoribosyltransferase. PRPP is created from ribose-5-phosphate by a further phosphorylation, serving as an energetic molecule to drive the reaction forward, while orotate is generated in several steps from carbamoyl phosphate and aspartate.{{cite book|url=https://www.ncbi.nlm.nih.gov/books/NBK22447/|section=Section 25.1In de Novo Synthesis, the Pyrimidine Ring Is Assembled from Bicarbonate, Aspartate, and Glutamine|title=Biochemistry|edition=5th|author=Berg JM, Tymoczko JL, Stryer L.|publisher=W H Freeman|year=2002}}

Uridine is regarded as a non-essential nutrient, as it is produced by the human body as needed and supplementation is not generally recommended, though it has been explored for specific applications.{{cite book|url=https://books.google.com/books?id=qtwr5pJNkzYC&pg=PA94|title=Nutritional and Herbal Therapies for Children and Adolescents: A Handbook|author=George M. Kapalka|publisher=Academic Press|year=2009|isbn=9780080958019}}

Some foods that contain uridine in the form of RNA are listed below. Although claimed that virtually none of the uridine in this form is bioavailable "since – as shown by Handschumacher's Laboratory at Yale School of Medicine in 1981{{cite journal |vauthors=Gasser T, Moyer JD, Handschumacher RE |title=Novel single-pass exchange of circulating uridine in rat liver |journal=Science |volume=213 |issue=4509 |pages=777–8 |year=1981 |pmid=7256279 |doi=10.1126/science.7256279 |bibcode=1981Sci...213..777G }} – it is destroyed in the liver and gastrointestinal tract, and no food, when consumed, has ever been reliably shown to elevate blood uridine levels'. This is contradicted by Yamamoto et al.,{{cite journal |vauthors=Yamamoto T, Moriwaki Y, Takahashi S, Tsutsumi Z, Ka T, Fukuchi M, Hada T |title=Effect of beer on the plasma concentrations of uridine and purine bases |journal=Metabolism: Clinical and Experimental |volume=51 |issue=10 |pages=1317–23 |year=2002 |pmid=12370853 |doi=10.1053/meta.2002.34041 }} plasma uridine levels rose 1.8-fold 30 minutes after beer ingestion, suggesting, at the very least, conflicting data. On the other hand, ethanol on its own (which is present in beer) increases uridine levels, which may explain the raise of uridine levels in the study by Yamamoto et al.{{cite journal |vauthors=Yamamoto T, Moriwaki Y, Takahashi S, Yamakita J, Tsutsumi Z, Ohata H, Hiroishi K, Nakano T, Higashino K |title=Effect of ethanol and fructose on plasma uridine and purine bases |journal=Metabolism: Clinical and Experimental |volume=46 |issue=5 |pages=544–7 |year=1997 |pmid=9160822 |doi=10.1016/s0026-0495(97)90192-x}}

In infants consuming mother's milk or commercial infant formulas, uridine is present as its monophosphate, UMP,{{cite journal|last1=Wurtman|first1=Richard|title=A Nutrient Combination that Can Affect Synapse Formation|journal=Nutrients|date=23 April 2014|volume=6|issue=4|pages=1701–1710|doi=10.3390/nu6041701|pmid=24763080|pmc=4011061|doi-access=free}} which is both bioavailable{{cite journal |vauthors=Carver JD |title=Advances in nutritional modifications of infant formulas |journal=The American Journal of Clinical Nutrition |volume=77 |issue=6 |pages=1550S–1554S |year=2003 |pmid=12812153 |url=http://www.ajcn.org/cgi/pmidlookup?view=long&pmid=12812153 |doi=10.1093/ajcn/77.6.1550S |doi-access=free }} and able to enter the circulation from the digestive tract.{{citation needed|date=September 2014}}

• goat's and sheep's milk and milk products
• Sugarcane extract[http://www.thebody.com/content/art30244.html Thebody.com]
• Tomatoes (0.5 to 1.0 g uridine per kilogram dry weight){{cite journal |last1=Hidalgo |first1=Alyssa |last2=Pompei |first2=Carlo |last3=Galli |first3=Antonietta |last4=Cazzola |first4=Sara |date=22 December 2004 |title=Uracil as an Index of Lactic Acid Bacteria Contamination of Tomato Products |journal=Journal of Agricultural and Food Chemistry |volume=53 |issue=2 |pages=349–355 |doi=10.1021/jf0486489 |pmid=15656671 |url=http://www.aseanfood.info/Articles/11018411.pdf |url-status=usurped |archive-url=https://web.archive.org/web/20111002025701/http://www.aseanfood.info/Articles/11018411.pdf |archive-date=2011-10-02}}
• Brewer's yeast (1.7% uridine by dry weight){{cite journal

|vauthors=Jonas DA, Elmadfa I, Engel KH, Heller KJ, Kozianowski G, König A, Müller D, Narbonne JF, Wackernagel W, Kleiner J | title=Safety considerations of DNA in food

| journal=Ann Nutr Metab

| volume=45

| issue=6

| pages=235–54

| year=2001

| pmid=11786646

| doi=10.1159/000046734

| citeseerx=10.1.1.600.3766

| s2cid=28474801

}}{{cite journal |vauthors=Storck R |title=Nucleotide composition of nucleic acids of fungi. I. Ribonucleic acids |journal=Journal of Bacteriology |volume=90 |issue=5 |pages=1260–4 |year=1965 |doi=10.1128/JB.90.5.1260-1264.1965 |pmid=5848326 |pmc=315810 }}

• Beer{{cite journal

|vauthors=Yamamoto T, Moriwaki Y, Takahashi S, Tsutsumi Z, Ka T, Fukuchi M, Hada T | title=Effect of beer on the plasma concentrations of uridine and purine bases

| journal=Metab Clin Exp

| volume=51

| issue=10

| pages=1317–23

| date=October 2002

| pmid=12370853

| doi=10.1053/meta.2002.34041

}}

• Broccoli
• Organ meats (liver, pancreas, etc.)

Consumption of RNA-rich foods may lead to high levels of purines (adenine and guanosine) in blood. High levels of purines are known to increase uric acid production and may aggravate or lead to conditions such as gout.{{Cite news|url=https://www.kidney.org/atoz/content/gout|title=Gout, Hyperuricemia & Chronic Kidney Disease|date=24 December 2015|work=The National Kidney Foundation|access-date=2017-11-24}}

Harvard researchers report that omega-3 fatty acids and uridine, two substances in foods such as fish, walnuts, molasses, and sugar beets, prevented depression in rats as effectively as antidepressant drugs. "Giving rats a combination of uridine and omega-3 fatty acids produced immediate effects that were indistinguishable from those caused by giving the rats standard antidepressant medications," said lead author of the study William Carlezon, director of McLean's Behavioral Genetics Laboratory.{{cite web|title=Food ingredients may be as effective as antidepressants|url=https://news.harvard.edu/gazette/story/2005/02/food-ingredients-may-be-as-effective-as-antidepressants/|website=Harvard Gazette|access-date=9 April 2018|date=10 February 2005}}{{cite journal

|vauthors=Carlezon WA, Mague SD, Parow AM, Stoll AL, Cohen BM, Renshaw PF | title=Antidepressant-like effects of uridine and omega-3 fatty acids are potentiated by combined treatment in rats

| journal=Biol Psychiatry

| volume=57

| issue=4

| pages=343–50

| date=February 2005

| pmid=15705349

| doi=10.1016/j.biopsych.2004.11.038

| s2cid=1834258

}}

Uridine plays a role in the glycolysis pathway of galactose.{{cite book | chapter-url = https://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=stryer&part=A2206#A2239 | chapter = Section 16.1 Glycolysis Is an Energy-Conversion Pathway in Many Organisms | title = Biochemistry | author = Stryer, Berg and Tymoczko | edition = 5th | location = New York | publisher = W H Freeman | date = 2002}} There is no catabolic process to metabolize galactose. Therefore, galactose is converted to glucose and metabolized in the common glucose pathway. Once the incoming galactose has been converted into galactose 1-phosphate (Gal-1-P), it is involved in a reaction with UDP-glucose, a glucose molecule bonded to uridine diphosphate (UDP). This process is catalyzed by the enzyme galactose-1-phosphate uridyl transferase and transfers the UDP to the galactose molecule. The end result is UDP-galactose and glucose-1-phosphate. This process is continued to allow the proper glycolysis of galactose.

• Deoxyuridine monophosphate
• Pseudouridine
• Uridine monophosphate

{{reflist|30em}}

{{Nucleobases, nucleosides, and nucleotides}}

{{Purinergics}}

Category:Nucleosides

Category:Pyrimidinediones

Category:Antidepressants

Category:Hydroxymethyl compounds