Inosinic Acid (Inosine 5′-Monophosphate, IMP)
1. Identity, Chemical Nature, and Common Forms
Inosinic acid, also known as inosine 5′-monophosphate (IMP), is a purine ribonucleotide composed of the nucleobase hypoxanthine linked to a ribose sugar moiety with a phosphate group esterified at the 5′ position, having the molecular formula C₁₀H₁₃N₄O₈P and a molecular weight of 348.21 g/mol. The systematic IUPAC name is [(2R,3S,4R,5R)-3,4-dihydroxy-5-(6-oxo-3H-purin-9-yl)oxolan-2-yl]methyl dihydrogen phosphate, commonly expressed as 9-β-D-ribofuranosyl-6-oxopurine-5′-monophosphate.
Compared to other major purine nucleotides, inosinic acid (IMP) possesses hypoxanthine, which differs from the adenine base in AMP by replacement of the 6-amino group with a 6-oxo group, and from the guanine base in GMP by the absence of a 2-amino group alongside the 6-oxo group. Inosinic acid is typically obtained as an odorless white crystalline powder or colorless crystals. It exhibits moderate solubility in water, approximately 70 g/L at 25°C, rendering it freely soluble for most aqueous applications, while it is slightly soluble in ethanol.
The CAS registry number for inosinic acid is 131-99-7. Several related forms and salts are recognized in commerce and regulation:
- Inosinic acid (free acid, E630): The parent compound; the form designated E630 under European Union food additive regulations. E630 is the food additive designation for inosinic acid (chemically known as inosine-5′-monophosphate, or IMP), a naturally occurring nucleotide, approved for use as a flavor enhancer and best known for intensifying the umami taste — the savory, meat-like flavor recognized as the fifth basic taste alongside sweet, sour, salty, and bitter.
- Disodium inosinate (E631): Disodium inosinate (E631) is listed in Commission Regulation (EU) No 231/2012 as an authorised food additive, categorized as "additives other than colours and sweeteners."
- Potassium 5′-inosinate (E632) and calcium 5′-inosinate (E633): Additional salt forms used in food applications and covered under the same EFSA re-evaluation programme as E630 and E631.
- Disodium 5′-ribonucleotides (E635): A 1:1 mixture of disodium inosinate and disodium guanylate (E627), known commercially as I+G, also recognized as a taste flavor.
Disodium inosinate, the commercially dominant form, can be produced by two methods: through sugar fermentation or from yeast extract. EFSA has evaluated disodium 5′-inosinate (IMP) produced by fermentation using Corynebacterium stationis KCCM 80235 as a sensory additive (flavouring compound) for use in feed and water.
2. Natural Sources and Occurrence
Inosinic acid serves as a key intermediate in purine nucleotide biosynthesis, acting as the first fully formed purine nucleotide in the de novo pathway and functioning as a precursor for the synthesis of adenosine monophosphate (AMP) and guanosine monophosphate (GMP). As such, it occurs endogenously in virtually all living cells. However, its occurrence as a free nucleotide — and therefore its dietary significance — is most prominent in animal-derived foods.
Adenosine triphosphate (ATP) is present in animal tissues at about 5–8 μmol/g in resting muscle but decreases rapidly during the early postmortem period, when it is rapidly degraded by ATPase into ADP and AMP. AMP is then enzymatically transformed by the action of AMP deaminase into inosine monophosphate (IMP), which can partly remain accumulated in postmortem meat and fish while the rest is dephosphorylated into inosine at a slower rate.
Fish muscles show higher variability, often reaching 80–800 mg/100 g, with dark (red) muscle exhibiting elevated concentrations compared to white muscle due to greater metabolic activity and ATP turnover — tuna, for instance, averages 188 mg/100 g, and sardines up to 280 mg/100 g in their darker portions. These levels decline over time as IMP degrades to inosine and hypoxanthine, reducing umami intensity during storage. In contrast, IMP is negligible in plant-based foods, where umami is predominantly derived from free glutamic acid rather than nucleotides like IMP or GMP. Animal-derived sources thus account for the majority of natural dietary exposure.
Glutamate, inosinate, and guanylate are the three dominant umami substances, and are found not only in kombu and katsuobushi, but in other foods as well. Glutamate is a component of vegetables such as tomatoes, and of fermented foods such as cheese, miso, or soy sauce. Inosinate is found in meat and fish, and guanylate in dried mushrooms.
Katsuobushi's distinct umami taste comes from its high inosinic acid content. Traditionally made katsuobushi, known as karebushi, is deliberately fermented with Aspergillus glaucus fungus in order to reduce moisture. In traditional katsuobushi production, the fish blocks are placed in hot water and simmered for 60 to 90 minutes in a step known as shajuku, which seals in the inosinate.
3. Traditional and Historical Use
Although inosinic acid as a defined chemical entity was not known to pre-modern culinary traditions, the foods richest in it — particularly dried fish preparations — have been used for centuries across East Asian cultures. The scientific identification of IMP as a distinct flavor-active compound is a product of early twentieth-century Japanese chemistry.
Katsuobushi is not just about smoking fish; the creation process is a tradition that has been handed down for nearly 400 years. Making katsuobushi involves drying katsuo, introducing beneficial mold that triggers fermentation, and creating a deeper, richer flavor. The process takes many months. Katsuobushi is simmered, smoked, and fermented skipjack tuna (Katsuwonus pelamis, sometimes referred to as bonito), also known as bonito flakes or broadly as okaka. Shaved katsuobushi and dried kelp — kombu — are the main ingredients of dashi, a broth that forms the basis of many soups (such as miso) and sauces in Japanese cuisine.
The scientific identification of IMP as a distinct flavor-active compound followed directly from the pioneering work of Japanese chemist Kikunae Ikeda, who in 1908 identified glutamate as the umami substance in kombu. The isolation of inosine 5′-monophosphate (IMP) occurred in 1913 when Japanese researcher Shintaro Kodama, a student of Kikunae Ikeda at the University of Tokyo, identified it as the primary umami compound in dried bonito flakes (katsuobushi). Kodama's work built on Ikeda's 1908 identification of glutamate as umami from kombu seaweed, shifting focus to nucleotide-based flavor enhancers derived from animal sources like fish.
Later, in 1957 (some sources say 1960), Dr. Akira Kuninaka of Yamasa Shoyu Research Laboratories discovered that guanylic acid (guanylate) from dried shiitake mushrooms was another umami substance. Crucially, Dr. Kuninaka also elucidated the "synergistic effect of umami," where the combination of glutamate with nucleotide-based umami substances like inosinate or guanylate significantly amplifies the perceived umami taste. These successive discoveries by Japanese scientists firmly established the scientific basis of umami.
The term "umami" gained international traction following the first International Symposium on Umami in 1985, further disseminating the depth of Japanese food culture to the world.
Inosine (the dephosphorylated metabolite of IMP) was also used in the 1970s as an athletic performance supplement in Western countries, representing an early, if unsupported, nutritional application of the IMP metabolic pathway. Inosine was a popular dietary supplement ingredient used in the 1970s to improve overall athletic performance. It was later discovered to have potential effects in the treatment of various autoimmune conditions as well as in the relief of symptoms associated with neurologic injury.
4. Key Constituents and Established Mechanisms of Action
4.1 Central Role in Purine Nucleotide Biosynthesis
Inosinic acid, also known as inosine monophosphate (IMP), is a purine nucleotide that serves as the central product of both the de novo and salvage pathways of purine metabolism. It plays a crucial role in the conversion of purine nucleotides to adenine and guanine nucleotides. Chemically, IMP is the first fully formed purine ribonucleotide and acts as a branch point for the synthesis of adenosine monophosphate (AMP) and guanosine monophosphate (GMP).
The formation of IMP occurs through a multistep enzymatic pathway, beginning with the construction of the purine ring on a ribose 5-phosphate backbone provided by 5-phosphoribosyl-1-pyrophosphate (PRPP). IMP is synthesized from ribose-5-phosphate through several enzymatic reactions involving phosphoribosyl pyrophosphate (PRPP) and amino acids such as glycine, glutamine, and aspartate.
IMP can also be formed by the deamination of adenosine monophosphate by AMP deaminase. This pathway is of particular relevance in skeletal muscle during high-intensity exercise. The breakdown of ATP results in formation of AMP and then inosine monophosphate by AMPD during high-intensity exercise when ATP usage exceeds resynthesis.
4.2 Feedback Regulation of Purine Synthesis
Inosinate and many other molecules inhibit the synthesis of 5-phosphoribosylamine from 5-phosphoribosyl-1-pyrophosphate (PRPP), disabling the enzyme glutamine-5-phosphoribosyl-1-pyrophosphate-amidotransferase. In other words, when levels of inosinate are high, this amidotransferase is inhibited, and, as a consequence, inosinate levels decrease; additionally, adenylate and guanylate are not produced, which means that RNA synthesis cannot be completed because of the lack of these two important RNA nucleotides.
4.3 Role of IMP Dehydrogenase (IMPDH)
IMP dehydrogenase (IMPDH) catalyzes the oxidation of IMP to XMP with the concomitant reduction of NAD to NADH. This reaction is the rate-limiting step of guanine nucleotide biosynthesis. IMPDH plays a central role in B and T lymphocyte replication. Two isoforms of human IMPDH, designated type I and type II, have been identified and sequenced; each is 514 amino acids, and they share 84% sequence identity.
IMPDH is a target of immunosuppressive, antiviral, anticancer, and antiparasitic chemotherapy. The most well-known example is mycophenolic acid (MPA), the active metabolite of the immunosuppressive drug mycophenolate mofetil, which inhibits IMPDH by occupying the NAD-binding site after IMP oxidation.
4.4 Uric Acid Production and Metabolic Fate
Hepatic metabolism of uric acid involves the sequential processing of purine nucleotides, including AMP, GMP, and IMP. IMP plays a pivotal role as a key intermediate in purine nucleotide biosynthesis, serving as a precursor for the synthesis of both AMP and GMP. IMP can be enzymatically deaminated, leading to the formation of inosine. Inosine, in turn, can undergo phosphorylation to become hypoxanthine. Hypoxanthine undergoes oxidative reactions catalyzed by xanthine oxidase (XOD), resulting in the production of xanthine. Xanthine is further oxidized by xanthine oxidase to uric acid, the terminal product of purine catabolism in humans.
4.5 Umami Taste Receptor Activation
Umami taste is elicited by many small molecules, including amino acids (glutamate and aspartate) and nucleotides (monophosphates of inosinate or guanylate). Mammalian taste buds respond to these diverse compounds via membrane receptors that bind the umami tastants. Several receptors have been proposed to underlie umami detection in taste buds, including two glutamate-selective G protein–coupled receptors, mGluR4 and mGluR1, and the taste bud–expressed heterodimer T1R1+T1R3.
The mGluRs are activated by glutamate and certain analogs but are not reported to be sensitive to nucleotides. In contrast, T1R1+T1R3 is activated by a broad range of amino acids and displays a strongly potentiated response in the presence of nucleotides.
It has been demonstrated that L-Glu binds in the hinge region of the T1R1-NTD inducing its closure, whereas IMP binds to an adjacent site, close to the opening, further stabilizing the closed conformation of the T1R1-NTD. This allosteric stabilization is the molecular basis for the synergistic enhancement of umami taste when IMP and glutamate are combined.
More recently, research has revealed that IMP's taste interactions extend beyond the umami receptor. Cellular assays revealed that IMP is able, like cyclamate, to modulate the response of TAS1R2/TAS1R3 and TAS1R3 alone stimulated by calcium ions. IMP also acted as an enhancer of TAS1R2/TAS1R3 when stimulated with sucralose, neotame, and cyclamate. These data demonstrate that IMP modulates sweet compound detection at the receptor level, acting via the TAS1R3 subunit.
5. Scientific Evidence by Area of Use
5.1 Flavor Enhancement and Umami Synergy
This is the most extensively studied and thoroughly established application of inosinic acid.
A salient feature of umami taste in rodents and humans is the impressive potentiation by purine nucleotides. This umami synergism probably occurs at the umami taste receptor T1R1+T1R3. In heterologous expression systems, the human T1R1+T1R3 heterodimer is activated by glutamate, whereas the mouse T1R1+T1R3 is activated by various amino acids. In both the human and the mouse T1R1+T1R3, occurrence of synergism between glutamate and inosine monophosphate (IMP) is demonstrated.
In rats, the response to a mixture of glutamate and 5′-inosinate is about 1.7 times larger than that to glutamate alone. In humans, the response to the mixture is about 8 times larger than that to glutamate alone. Since glutamate and 5′-inosinate are contained in various foods, umami induced by the synergism is tasted in daily eating.
IMP is commonly used in synergy with monosodium glutamate (MSG) to provide umami taste. For example, it has a significant flavor synergy with MSG at the ratio of 1:7. The strength of flavor-enhancing of the combination of 98% MSG with 2% I+G (disodium inosinate and disodium guanylate 1:1) is around four times that of MSG alone.
Evidence strength: The molecular and sensory mechanisms are well-established through peer-reviewed receptor biology, electrophysiology, and human psychophysical studies. This is one of the strongest bodies of evidence associated with any function of inosinic acid.
5.2 Skeletal Muscle Energy Metabolism and Exercise Physiology
IMP accumulates markedly in human skeletal muscle during intense exercise as part of normal purine nucleotide catabolism. The influence of exercise intensity on the accumulation of inosine monophosphate (IMP) in human skeletal muscle has been investigated. Ten men cycled at workloads corresponding to 40%, 75%, and 100% of their maximal oxygen uptake (VO₂ max). Muscle IMP was below the detection limit (less than 0.01 mmol/kg dry wt) at rest and after exercise at 40% of VO₂ max, but increased to 0.26 ± 0.06 and 3.50 ± 0.51 mmol/kg dry wt after exercise at 75% and 100% of VO₂ max, respectively.
Accumulation of IMP corresponded to a similar decrease in the total adenine nucleotide content. The muscle content of IMP was positively related to lactate and negatively related to phosphocreatine (PCr). IMP was formed in both fiber types, but the IMP content at fatigue was about twice as high in type II fibers as in type I fibers.
Despite the endogenous role of IMP in muscle metabolism, exogenous supplementation with inosine (IMP's metabolic precursor and dephosphorylated derivative) as an ergogenic aid has not demonstrated clinical efficacy. Two well-controlled studies used the recommended supplementation protocol for endurance athletes and reported no beneficial effects of inosine on cardiovascular-respiratory or metabolic functions during submaximal or maximal exercise, nor was there any effect on time to complete a simulated three-mile race on a treadmill. Both studies actually suggested inosine could be ergolytic for certain athletic endeavors involving anaerobic glycolysis.
Evidence strength: The role of endogenous IMP as a muscle metabolite during exercise is well-documented by human physiological studies. As an exogenous ergogenic supplement, the evidence is negative — no benefit was observed in controlled human trials, and potential adverse (ergolytic) effects were noted.
5.3 Animal Nutrition: Growth Performance and Meat Quality
A body of animal research (principally in pigs and fish) has examined dietary IMP supplementation as a means to support nucleotide availability during periods of rapid growth or stress.
Inosine 5′-monophosphate (5′-IMP) is an essential nucleotide for de novo nucleotide biosynthesis and metabolism of energy, proteins, and antioxidants. Nucleotides are conditionally essential, as they cannot be produced sufficiently rapidly to meet the needs of the body in situations of oxidative stress or rapid muscle growth. A deficient intake of nucleotides can result in decreased ATP and GTP synthesis and impaired metabolism.
Supplementation of finishing pig diets with 5′-IMP reduces the relative weight of the liver and increases oxygen consumption during mitochondrial respiration without changing the ADP/O ratio, indicating an increase in the respiratory efficiency of liver mitochondria. A reduction in liver lipid peroxidation and an increase in muscle creatine were also observed. Moreover, 5′-IMP supplementation increases slaughter weight, lean meat yield, sarcomere length, and backfat thickness in finishing barrows.
Evidence strength: These findings are from animal (porcine and aquaculture) studies only. No controlled human trials on this application have been identified. The results cannot be directly extrapolated to human supplementation outcomes.
5.4 Parkinson's Disease and Neuroprotection
IMP itself is not the agent directly studied in clinical trials for neuroprotection. Rather, inosine — its immediate metabolic precursor — has been investigated as an oral precursor for raising circulating uric acid (urate), which has antioxidant properties and epidemiological associations with reduced Parkinson's disease (PD) risk.
Inosine is an orally bioavailable precursor of urate, widely consumed as a nutritional supplement, and previously administered in several multi-year clinical trials for multiple sclerosis. Urate is a potent endogenous antioxidant and metal chelator and the end product of purine metabolism in humans.
The Safety of Urate Elevation in Parkinson Disease (SURE-PD) trial, a phase II randomized, double-blind, placebo-controlled, dose-ranging trial of oral inosine in PD, demonstrated that inosine supplementation leads to a dose-dependent increase in blood and CSF urate levels in patients with PD. Although the study was not powered to test efficacy, secondary analyses demonstrated non-futility of inosine treatment for slowing disability.
In the subsequent SURE-PD3 phase 3 randomized clinical trial, inosine was dosed by blinded titration to increase serum urate concentrations to 7.1–8.0 mg/dL (n = 149) or matching placebo (n = 149) for up to 2 years, assessing whether sustained urate-elevating treatment with the urate precursor inosine could slow clinical disease progression among patients with early Parkinson disease.
In this largest study, 298 individuals with early PD not yet requiring treatment were randomized to receive placebo or oral inosine. Clinical progression was monitored with the MDS-UPDRS rating scale and dopamine transporter (DAT) imaging. The study was halted early when an interim analysis disclosed no benefit in clinical outcome or imaging. These results do not support the concept that urate is a biologically relevant neuroprotectant in PD, but several investigators have pointed to features of the trial that may have led to a false negative outcome.
Evidence strength: Phase 2 data for inosine's urate-elevating effect in PD patients is established. The phase 3 (SURE-PD3) trial, the largest and most rigorous study, failed to meet its primary endpoint. Overall, clinical evidence for a neuroprotective benefit in PD from inosine or IMP supplementation is currently negative, though debate about study design continues.
5.5 Purines, IMP, and Uric Acid in Multiple Sclerosis
Inosine has also been evaluated as a means to raise urate in multiple sclerosis (MS), given the observation that urate is a potent peroxynitrite scavenger and MS patients often have lower urate levels. A clinical trial was conducted to determine whether raising serum uric acid levels through oral administration of inosine is well tolerated and may benefit patients with multiple sclerosis. An important aspect of the safety profile was whether raising the serum uric acid levels elevates blood pressure. During the 1-year trial, blood pressure and serum uric acid levels were monitored in 16 patients, with both parameters recorded across 69 visits at baseline/placebo phase and 138 visits during inosine treatment.
Evidence strength: This MS trial was small (n = 16) and of limited duration, functioning primarily as a safety/feasibility study. No efficacy conclusions for MS can be drawn from this data alone.
6. Body Systems and Health Areas Associated with Inosinic Acid
- Purine and nucleotide metabolism: Inosinic acid serves as a key intermediate in purine nucleotide biosynthesis, acting as the first fully formed purine nucleotide in the de novo pathway and functioning as a precursor for synthesis of AMP and GMP. It plays essential roles in cellular metabolism, including as a human metabolite, primarily located in the cytoplasm, extracellular space, and mitochondria.
- Immune system: IMPDH plays a central role in B and T lymphocyte replication. Proliferating B and T lymphocytes are singularly dependent on the de novo pathway, rather than the salvage pathway, for purine biosynthesis.
- Central nervous system: In the central nervous system (CNS), purine metabolism displays distinct patterns, with a greater dependence on the salvage pathway. The enzyme hypoxanthine-guanine phosphoribosyltransferase (HGPRT) catalyzes the conversion of hypoxanthine to IMP in this salvage pathway, which is crucial for neural nucleotide metabolism.
- Skeletal muscle: IMP accumulates in skeletal muscle during high-intensity exercise as a marker of adenine nucleotide depletion and is part of the purine nucleotide cycle that facilitates ATP regeneration and ammonia production during intense physical work.
- Gastrointestinal and sensory systems: IMP acts on taste receptors in the oral cavity, contributing to the perception of umami taste with direct food intake behavior implications.
- Renal system: The potential side effects of inosine relate to the resulting elevated urate (uric acid) levels (hyperuricemia). Hyperuricemia has been linked to gout, which generally develops in people with serum urate concentrations above 8 mg/dL, and to the formation of urate stones in the kidneys or ureters (urolithiasis).
- Cardiovascular system: High urate levels have also been associated with high blood pressure and increased risk for cardiovascular events.
7. Dosage Forms and Reported Dosages
Inosinic acid and its salts are encountered in several forms depending on the application context:
- Food additive (flavor enhancer): Used at low levels (typically milligrams per serving) in processed foods. The combination of 98% MSG with 2% I+G (inosinate and guanylate blend) achieves around four times the flavor-enhancing strength of MSG alone. No specific maximum use level has been set by JECFA or EFSA for inosinic acid in food, as it is used at the lowest level necessary to achieve the desired effect (quantum satis principle in EU regulation).
- Animal feed additive: In swine nutrition research, supplementation of finishing pig diets with 5′-IMP was investigated at varying dietary concentrations (the pig study referenced doses of 5′-IMP at differing levels in feed formulations). EFSA evaluated disodium 5′-inosinate (IMP) produced by fermentation as a sensory additive (flavouring compound) in feed and water for drinking for all animal species.
- Clinical research (inosine, the metabolic precursor): In the SURE-PD3 phase 3 trial, inosine was dosed by blinded titration to increase serum urate concentrations to 7.1–8.0 mg/dL in participants treated for up to 2 years. In a separate open-label Japanese PD trial, each patient was administered febuxostat 20 mg and inosine 500 mg twice per day (after breakfast and dinner) for 8 weeks.
No established human dietary reference value, recommended daily intake, or tolerable upper intake level has been set by major regulatory bodies (FDA, EFSA, NIH) for inosinic acid or IMP as a dietary supplement in healthy adults. Dosage ranges used in clinical research pertain to inosine (the metabolically related nucleoside), not directly to IMP as sold.
8. Safety Considerations and Notable Interactions
8.1 Regulatory Safety Status as a Food Additive
The safety of inosinic acid and its salts when used as food additives has been approved by the U.S. Food and Drug Administration (FDA), the European Food Safety Authority (EFSA), and the Joint FAO/WHO Expert Committee on Food Additives (JECFA), as well as other authorities. E630 is considered safe by regulatory authorities including EFSA. For healthy adults, no adverse effects have been documented at typical dietary intake levels.
In the European Union, E630 is authorized under Regulation (EC) No 1333/2008 on food additives. It must be declared on ingredient lists either as E630 or by its chemical name inosinic acid.
8.2 Purine Load and Uric Acid Elevation
Both IMP and adenosine are processed into inosine. The transformation of inosine to hypoxanthine is catalyzed by purine nucleoside phosphorylase, and eventually hypoxanthine utilizes the dual oxidation of xanthine oxidase (XO) to produce uric acid. Consequently, dietary intake of IMP contributes to the body's total purine load and can raise serum uric acid.
Gout patients should be aware that inosinic acid is metabolized in the body to uric acid. Elevated intake can raise blood uric acid levels and may trigger gout attacks. Individuals with hyperuricemia — those with already elevated uric acid levels — may experience further increases when consuming purine-rich additives such as E630.
Hyperuricemia, defined as high levels of blood uric acid, is the major etiological factor of gout. A number of epidemiological reports have increasingly linked hyperuricemia with cardiovascular and neurological diseases. Studies highlighting the pathogenic mechanisms of uric acid point to an inflammatory response as the primary mechanism for inducing gout, with monosodium urate (MSU) crystals inducing an inflammatory reaction recognized by Toll-like receptors (TLRs).
8.3 Infants
Under EU regulations, products containing nucleotides such as E630 must carry a statement indicating they are not suitable for infants under 12 weeks of age. Due to the different metabolic processing of nucleotides in babies, products containing E630 should be avoided for infants.
8.4 Kidney Stone Risk
Hyperuricemia has been linked to the formation of urate stones in the kidneys or ureters (urolithiasis). In most uric acid stone formers, the primary pathophysiologic defect is an excessively acidic urine pH rather than hyperuricemia.
8.5 Cardiovascular Associations
A number of epidemiological reports have increasingly linked hyperuricemia with cardiovascular and neurological diseases. High urate levels have also been associated with high blood pressure and increased risk for cardiovascular events. These associations are for sustained hyperuricemia and are not established at normal dietary intake levels of IMP from food sources.
8.6 Interactions with Xanthine Oxidase Inhibitors
Because IMP is ultimately catabolized to uric acid via the xanthine oxidase pathway, drugs that inhibit this enzyme — such as allopurinol or febuxostat — will alter the metabolic fate of IMP-derived hypoxanthine. In clinical research exploring this pathway, treatment with febuxostat and inosine was shown to increase blood hypoxanthine and ATP in healthy adults. This represents an important pharmacokinetic interaction: combining IMP/inosine with xanthine oxidase inhibitors shifts purine catabolism toward the salvage pathway rather than toward uric acid production.
8.7 Genetic Enzyme Deficiencies
A variant in the AMPD1 gene results in a premature stop codon (AMPD1 C34T, rs17602729) and complete deficiency of the AMPD protein and diminished AMP metabolism, producing muscle fatigue, weakness, and cramping. In individuals carrying this relatively common variant, the conversion of AMP to IMP during high-intensity exercise is impaired. Additionally, the enzyme HGPRT, which converts hypoxanthine back to IMP in the salvage pathway, is absent in Lesch-Nyhan syndrome. The absence of HGPRT in Lesch-Nyhan Syndrome affects all tissues, including the brain, with the highest level of activity in the basal ganglia.
8.8 Suitability for Certain Dietary Groups
Since inosinic acid is predominantly derived from animal sources or microbial fermentation, it may not be suitable for vegans or strict vegetarians. Commercial IMP for food use is typically obtained from chicken byproducts or other meat industry waste, although fermentation-derived versions exist.
References
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