858 Oxalic acid Oxalic acid is a dicarboxylic acid. It is a colorless crystalline solid that dissolves in water to give colorless, acidic solutions. In terms of acid strength, it is much stronger than acetic acid. Oxalic acid, because of its di-acid structure can also act as a chelating agent for metal cations. About 25% of produced oxalic acid is used as a mordant in dyeing processes. It is also used in bleaches, especially for pulpwood. Oxalic acid's main applications include cleaning (it is also found in baking powder) or bleaching, especially for the removal of rust. Oxalic acid is found in a number of common foods with members of the spinach family being particularly high in oxalates. Beat leaves, parsley, chives and cassava are quite rich in oxalate. Rhubarb leaves contain about 0.5% oxalic acid and jack-in-the-pulpit (Arisaema triphyllum) contains calcium oxalate crystals. Bacteria naturally produce oxalates from the oxidation of carbohydrates. At least two pathways exist for the enzyme-mediated formation of oxalate in humans. In one pathway, oxaloacetate (part of the citric acid cycle) can be hydrolyzed to oxalate and acetic acid by the enzyme oxaloacetase. Oxalic acid can also be generated from the dehydrogenation of glycolic acid, which is produced by the metabolism of ethylene glycol. Oxalate is a competitive inhibitor of lactate dehydrogenase (LDH). LDH catalyses the conversion of pyruvate to lactic acid oxidizing the coenzyme NADH to NAD+ and H+ concurrently. As cancer cells preferentially use aerobic glycolysis, inhibition of LDH has been shown to inhibit tumor formation and growth. However, oxalic acid is not particularly safe and is considered a mild toxin. In particular, it is a well-known uremic toxin. In humans, ingested oxalic acid has an oral lowest-published-lethal-dose of 600 mg/kg. It has been reported that the lethal oral dose is 15 to 30 grams. The toxicity of oxalic acid is due to kidney failure caused by precipitation of solid calcium oxalate, the main component of kidney stones. Oxalic acid can also cause joint pain due to the formation of similar precipitates in the joints. 144-62-7 971 C2H2O4 89.995310 White crystals 189.5°C 220 mg/mL at 25°C The affinity of divalent metal ions is sometimes reflected in their tendency to form insoluble precipitates. Thus in the body, oxalic acid also combines with metals ions such as Ca2+, Fe2+, and Mg2+ to deposit crystals of the corresponding oxalates, which irritate the gut and kidneys. (2) Therefore the toxicity of oxalic acid is due to kidney failure caused by precipitation of solid calcium oxalate, the main component of kidney stones. Oxalic acid can also cause joint pain due to the formation of similar precipitates in the joints. Ingestion of ethylene glycol results in oxalic acid as a metabolite that can also cause acute kidney failure. Oxalic acid is not metabolized but excreted in the urine. Oral LDLo (lowest published lethal dose) of 600 mg/kg. It has been reported that the lethal oral dose is 15 to 30 grams. No indication of carcinogenicity (not listed by IARC). (L135) Oxalic acid and oxalates are abundantly present in many plants, most notably fat hen (lamb's quarters), sorrel, and Oxalis species. The root and/or leaves of rhubarb and buckwheat are listed being high in oxalic acid.[8] Other edible plants that contain significant concentrations of oxalic acid include—in decreasing order—star fruit (carambola), black pepper, parsley, poppy seed, amaranth, spinach, chard, beets, cocoa, chocolate, most nuts, most berries, and beans. (L618) Because it binds vital nutrients such as calcium, long-term consumption of foods high in oxalic acid can be problematic. Healthy individuals can safely consume such foods in moderation, but those with kidney disorders, gout, rheumatoid arthritis, or certain forms of chronic vulvar pain (vulvodynia) are typically advised to avoid foods high in oxalic acid or oxalates. The calcium oxalate precipitate (better known as kidney stones) obstruct the kidney tubules. Conversely, calcium supplements taken along with foods high in oxalic acid can cause calcium oxalate to precipitate out in the gut and drastically reduce the levels of oxalate absorbed by the body (by 97% in some cases.) Chronically high levels of oxalic acid are associated with at least 2 inborn errors of metabolism including: Type I primary hyperoxaluria and Primary hyperoxaluria. Oxalate stones in primary hyperoxaluria tend to be severe, resulting in relatively early kidney damage (before age 20), which impairs the excretion of oxalate leading to a further acceleration in accumulation of oxalate in the body. After the development of renal failure patients may develop oxalate deposits in the bones, joints and bone marrow. Severe cases may develop haematological problems such as anaemia and thrombocytopaenia. The deposition of oxalate in the body is sometimes called "oxalosis" to be distinguished from "oxaluria" which refers to oxalate in the urine. Oxalic acid poisoning symptoms include weakness, burning in the mouth, death from cardiovascular collapse, on the respiratory system, throat – burning in the throat, abdominal pain, nausea, vomiting, diarrhea, convulsions, and coma. Acute Exposure: If oxalic acid is swallowed, immediately give the person water or milk, unless instructed otherwise by a health care provider. DO NOT give water or milk if the person is having symptoms (such as vomiting, convulsions, or a decreased level of alertness) that make it hard to swallow. If acute exposure occurs to the eyes, irrigate opened eyes for several minutes under running water. Chronic exposure: in some patients with primary hyperoxaluria type 1, pyridoxine treatment (vitamin B6) may decrease oxalate excretion and prevent kidney stone formation. 2009-06-09T20:08:59Z 2014-12-24T20:22:53Z http://en.wikipedia.org/wiki/Oxalic acid C00209 109600 138500 167030 240400 259900 260000 260005 16995 CUPRIZONE D019815 Oxalic Acid DB03902 OXD 3709 true OC(=O)C(O)=O C2H2O4 InChI=1S/C2H2O4/c3-1(4)2(5)6/h(H,3,4)(H,5,6) InChIKey=MUBZPKHOEPUJKR-UHFFFAOYSA-N 90.0349 89.995308552 Endogenous Solid HMDB02329 CHEMBL146755 946 <p>Giuseppe Messina, Giovanni M. Sechi, Loreno Lorenzoni, Giovanni Chessa, &#8220;Method of preparation of oxalic acid esters and amides.&#8221; U.S. Patent US4981963, issued July, 1971.</p>