is a nucleoside
that is formed when hypoxanthine
is attached to a ribose
ring (also known as a ribofuranose
) via a β-N9- glycosidic bond
Inosine is commonly found in tRNA
s and is essential for proper translation of the genetic code in wobble base pair
Knowledge of inosine metabolism has led to advances in immunotherapy
in recent decades. Inosine monophosphate is oxidised by the enzyme inosine monophosphate dehydrogenase
, yielding xanthosine monophosphate
, a key precursor in purine
metabolism. Mycophenolate mofetil
is an anti-metabolite, anti-proliferative drug that acts as an inhibitor of inosine monophosphate dehydrogenase. It is used in the treatment of a variety of autoimmune
diseases including granulomatosis with polyangiitis
because the uptake of purine by actively dividing B cell
s can exceed 8 times that of normal body cells, and, therefore, this set of white cells (which cannot operate purine salvage pathways) is selectively targeted by the purine deficiency resulting from inosine monophosphate dehydrogenase (IMD) inhibition.
is converted to adenosine
or inosine monophosphate
(IMP), either of which, in turn, is converted into inosine (I), which pairs with adenine (A), cytosine
(C), and uracil
Purine nucleoside phosphorylase
intraconverts inosine and hypoxanthine
Inosine is also an intermediate in a chain of purine nucleotides reactions required for muscle movements.
It was tried in the 1970s in Eastern countries for improving athletic performance. Nevertheless, the clinical trials for this purpose showed no improvement.
It has been shown that inosine has neuroprotective properties. It has been proposed for spinal cord injury; because it improves axonal rewiring, and for administration after stroke
, because observation has shown that axonal rewiring is encouraged.
After ingestion, inosine produces uric acid that is suggested to be a natural antioxidant and a peroxynitrite
scavenger with potential benefits to patients with multiple sclerosis
(MS). Uric Acid: Natural Scavenger Of Peroxynitrite
Peroxynitrite has been correlated with axon degeneration link
. In 2003, a study was initiated at the University of Pennsylvania MS Center to determine whether raising the levels of uric acid by the administration of inosine would slow the progression of MS. The study was completed in 2006 but the results were not reported to NIH. A subsequent publication hinted at potential benefits but the sample size (16 patients) was too small for a definitive conclusion. In addition, the side effect of the treatment was the development of kidney stones in four of 16 patients. Thus, additional studies are necessary to prove the treatment's efficacy.
Its phase II trials for Parkinson's disease is now ended, it will continue to phase III trials. Earlier trials had suggested those with the highest serum urate levels had lower progression of Parkinson's symptoms. The trial uses inosine to raise urate levels in those with levels lower than the population mean (6 mg/dL).
(named Boston Life Sciences when patent was granted) patented the treatment for stroke link
and is currently investigating the drug in the MS setting. Alseres pharma drug description
In the Anatomical Therapeutic Chemical Classification System
, it is classified as an antiviral
Inosine is a natural ligand for the Benzodiazepine binding site on the GABA A receptor.
When designing primer
s for polymerase chain reaction
, inosine is useful in that it can pair with any natural base. This allows for design of primers that span a single-nucleotide polymorphism
, without the polymorphism disrupting the primer's annealing efficiency.
However, inosine pairs preferentially with cytidine (C) and its introduction to RNA, e.g. by the action of ADARs, thereby destabilizes double-stranded RNA by changing AU base-pairs to
IU mismatches.(Bass and Weintraub, Cell, 1988).
Despite lack of clinical evidence that it improves muscle development, inosine remains an ingredient in some fitness supplements.
Inosine has also been found to be an important feed stimulant by itself or in combination with certain amino acids
in some species of farmed fish
. For example, inosine and inosine-5-monophosphate have been reported as specific feeding stimulants for turbot
fry, (Scophthalmus maximus
) Mackie, A.M. (1987). Identification of the gustatory feeding stimulants. In: Chemoreception in Fishes. (ed. T.J. Hara). Elsevier Scientific Publishing Co., Amsterdam, pp. 275-291. and Japanese amberjack
, (Seriola quinqueradiata
).Takeda, M. Takii, K. & Matsui, K. (1984). Identification of feeding stimulants for juvenile eel. Bull. Jap. Soc. Scient. Fish., 50: 645-651. The main problem of using inosine and/or inosine-5-monophosphate as feeding attractants is their high cost. However, their use may be economically justified within larval feeds for marine fish larvae during the early weaning period, since the total quantity of feed consumed is relatively low.