Introduction
Uric acid is a breakdown substance of purines which exist in body tissues and some food and drinks. Purines are a type of chemical compound in nature consisted in nucleic acids (DNA and RNA). Uric acid is created in the body via purine metabolism and circulated within the bloodstream, and it will be excreted in urine as waste. As a result, there is a certain balanced amount of uric acid in the bloodstream, which is of great importance to the functions of body
[1].
Uric acid is composed in the form of urate of ammonia, and it is the primary constituent of the urine of birds and reptiles. Uric acid helps to keep the birds' weight down which is crucial for their flight. Due to its acidic properties, uric acid from birds does damage paints on cars. Insects produce uric acid during protein catabolism. In addition, uric acid helps to make butterflies iridescent. Its crystals also reflect the light produced in fireflies by bioluminescence
[2].
Properties and Preparation
Uric acid is a colorless, odorless and tasteless solid with molecular formula C5H4N4O3. It is largely insoluble in water (60 mg/L, at 20 °C)
[2]. It is soluble in 1 M NaOH (50 mg/ml)
[3]. Rather than melt, it decomposes in air above 250°C.
Uric acid is produced from purines by the enzyme xanthine oxidase via the purine metabolism pathway. In the majority of mammals, uric acid is further degraded to allantoin via the urate oxidase (uricase) enzyme. Allantoin is then freely excreted from the body in the urine. Humans, apes, and certain New World monkeys have higher uric acid levels compared with other mammals
[4]. Commercially, uric acid has been prepared from guano, which is essentially the droppings of bats or seabirds. Large quantities of guano can be found on some islands. Uric acid can be produced via extracting guano with alkali and then precipitating with acid
[5][6].
Chemical Properties
Uric acid (C5H4O3N4) is a white solid that is insoluble in cold water, alcohol, or ether and sparingly soluble in hot water. It acts as a weak dibasic acid, creating two series of salts, with most being very slightly soluble in water (except for lithium urate, which is soluble).
Occurrence
Uric acid is found in the urine, blood, and muscle juices of carnivorous animals (herbivorous animals secrete hippuric acid), in the excrement of birds, serpents and insects, and is an oxidation product of the complex nitrogenous compounds of the animal organism.
Uses
Uric Acid is a heterocyclcic compound that is created when purine nucleotides are broken down of by the human body. High blood concetration of Uric Acid is known as hyperuricemia and is often associated with a wide range of disorders and medical conditions such as gout, diabetes and metabolic syndrome. Uric acid may be a marker of oxidative stress and may have a potential therapeutic role as an antioxidant.
Definition
A nitrogen compound
produced from purines. In certain animals
(e.g. birds and reptiles), it is the main excretory product resulting from breakdown
of amino acids. In humans, uric acid crystals in the joints are the cause of gout.
Definition
uric acid: The end product of purinebreakdown in most primates, birds,terrestrial reptiles, and insects andalso (except in primates) the majorform in which metabolic nitrogen isexcreted. Being fairly insoluble, uricacid can be expelled in solid form,which conserves valuable water inarid environments. The accumulationof uric acid in the synovial ?uidof joints causes gout.
Biochem/physiol Actions
Uric acid is an insoluble catabolite produced by adenine and guanine metabolism. Accumulation of uric acid leads to gout, hyperuricemia, arthritis and renal failure. Elevated uric acid levels contributes to hypertension and pathogenesis of cardiovascular disease. Low uric acid levels associated with Parkinson′s disease and multiple sclerosis, may elicit protective functionality. High levels of uric acid in patients with chronic obstructive pulmonary disease (COPD) may serve as potential marker for diagnosis.
Safety Profile
Experimental
reproductive effects. Mutation data
reported. When heated to decomposition it
emits toxic fumes of NOx.
Purification Methods
Crystallise uric acid from hot distilled H2O (the solubility in H2O is 1part/39,000parts at 18o and 1part/2,000parts at 100o). It is best purified by dissolving in an alkaline solution and acidifying with dilute HCl and drying it at 100o in a vacuum. [Bergmann & Dikstein J Am Chem Soc 77 691 1955, Lister Purines Part II, Fused Pyrimidines Brown Ed, Wiley-Interscience pp256-257 1971, ISBN 0-471-38205-1, Beilstein 26 H 513, 26 I 151, 26 II 293, 26 III/IV 2619.]
