He Pyruvic acid Is a 2-oxo-monocarboxylic acid which is the 2-keto derivative of propionic acid. Its formula is CH3COCOOH.
Pyruvic acid (CH3COCOOH) is the simplest of the alpha-keto acids, with a carboxylic acid and a functional ketone group. Its structure is presented in Figure 1 (EMBL-EBI, 2017).
Figure 1: structure of pyruvic acid.
Pyruvate, the conjugate base (CH3COCOO-) is a key intermediate in the metabolism of carbohydrates, proteins and fats. In thiamine deficiency, its oxidation is delayed and accumulates in tissues, especially in nerve structures (Pyruvic Acid, 1997).
Pyruvate is the product of the aerobic metabolism of glucose known as glycolysis. Pyruvate can be converted into carbohydrates through gluconeogenesis, to fatty acids or energy through acetyl-CoA, to amino acid alanine and to ethanol.
In 1834, Théophile-Jules Pelouze Distilled both tartaric acid (L-tartaric acid) and racemic acid (a mixture of D- and L-tartaric acid) and isolated pyroartic acid (methyl succinic acid). It also distilled another acid that was characterized the following year by Jöns Jacob Berzelius And which he called pyruvic acid.
In the laboratory, pyruvic acid can be prepared by heating a mixture of tartaric acid and potassium hydrogen sulfate.
This can be done in two ways, either by oxidizing propylene glycol with a strong oxidant (eg potassium permanganate) or by hydrolyzing acetyl cyanide, formed by reacting acetyl chloride with potassium cyanide:
CH3COCl + KCN → CH3COCN + KCl
CH3COCN → CH3COCOOH
Physical and chemical properties of pyruvic acid
Pyruvic acid is a colorless or amber, viscous liquid with the odor of bitter vinegar (Royal Society of Chemistry, 2015). Their appearance is shown in figure 2.
Figure 2: appearance of pyruvic acid.
The compound has a molecular weight of 88.06 g / mol and a density of 1,250 g / ml. It has a melting point of 11.8 ° C and a boiling point of 164 ° C. The compound is very soluble in water, being able to dissolve 1000 mg for each ml of solvent. Pyruvic acid is a weak acid, has a pKa of 2.5 (National Center for Biotechnology Information, 2017).
Reactivity and hazards
Pyruvic acid is classified as a stable compound, although it is combustible. It is incompatible with oxidizing agents and strong bases.
Those who take large doses of supplemental pyruvate - usually greater than 5 grams daily - have reported gastrointestinal symptoms, including abdominal discomfort and bloating, gas and diarrhea. One case of a child who died receiving pyruvate intravenously for restrictive cardiomyopathy (Pyruvic acid, 2016) was reported.
Pyruvic acid is very dangerous in case of skin contact (irritant), eye contact (irritant), ingestion, inhalation. It is also corrosive. Spray liquid or mist can produce tissue damage particularly in the mucous membranes of the eyes, mouth and respiratory tract.
Contact with skin may cause burns. Inhalation of spray mist may cause severe irritation of the respiratory tract, characterized by suffocation, coughing or shortness of breath.
The inflammation of the eye is identified by redness, irrigation and irritation or itching. The inflammation of the skin is characterized by strong itching, peeling, redness and occasional blisters can form.
In case of contact with eyes
Check and remove contact lenses. Immediately flush eyes with copious amounts of water for at least 15 minutes with cold water.
In case of contact with skin
Immediately flush affected area with plenty of water for at least 15 minutes while removing contaminated clothing and shoes. Cover irritated skin with a tranquilizer.
Wash clothing and shoes before putting them back on. If contact is severe, rub and rinse with a disinfectant soap and cover the skin contaminated with an anti-bacterial cream.
In case of inhalation:
The victim should be moved to a cool place. If not breathing, give artificial respiration. If breathing is difficult, give oxygen.
In case of ingestion
If the compound is ingested, do not induce vomiting unless directed to do so by medical personnel. It is advisable to drink water in large quantities for the dilution of the compound. Loose clothing, such as the collar, belt or tie, should be loosened.
In all cases, medical attention should be obtained immediately (Material Safety Data Sheet Pyruvic acid, 2013).
Importance and uses
Pyruvic acid, or pyruvate, is a key intermediate in the pathways of glycolytic and pyruvate dehydrogenase, which are involved in the production of biological energy.
Pyruvate is widely found in living organisms. It is not an essential nutrient, as it can be synthesized in the cells of the body. Some fruits and vegetables are rich in pyruvate, for example the red apple.
The central cellular pathway of ATP synthesis begins with glycolysis, a form of fermentation in which glucose is transformed into other sugars in a series of nine enzymatic reactions. Each successive reaction involves an intermediate sugar containing phosphate.
In the process, six-carbon glucose is converted into two molecules of three-carbon pyruvic acid. Part of the energy released through the glycolysis of each glucose molecule is captured in the formation of two molecules of ATP.
The second stage in the metabolism of sugars is a set of interrelated reactions called the citric acid cycle or Krebs cycle.
This cycle takes the three-carbon pyruvic acid produced in glycolysis and uses its carbon atoms to form carbon dioxide (CO2) while transferring its hydrogen atoms to special carrier molecules where they are held in high energy bond (Michael Cuffe , 2016).
Pyruvate serves as a biofuel becoming acetyl coenzyme A, which enters the citric acid cycle or Krebs, where it is metabolized to produce ATP aerobically.
The energy can also be obtained anaerobically from pyruvate, through its conversion into lactate.
It is important to note that in aerobic glycolysis, the production of pyruvate and its subsequent conversion to acetyl CoA generates 10 molecules of ATP per molecule of pyruvate, whereas its reduction to lactate produces only 2 ATP per molecule of pyruvate (Human metabolome data base, 2017).
Figure 3: role of pyruvic acid in cellular respiration.
Pyruvate is also converted to oxalacetate by the action of the above pyruvate carboxylase. Oxalacetate is an important intermediary for the metabolic pathways of neoglucogenesis and lipogenesis, neurotransmitter biosynthesis and glucose-induced insulin secretion through pancreatic islets.
Through the action of the enzyme alanine transaminase, pyruvate is reversibly converted to alanine, one of the 10 non-essential amino acids produced by the organism. The importance of this reaction lies in the interconversion of nutrients between skeletal muscle and liver, in the so-called alanine glucose cycle or Cahill cycle.
When muscles degrade amino acids for energy needs, the resulting nitrogen is transaminated to pyruvate to form alanine.
This is done by the enzyme alanine transaminase, which converts glutamate and pyruvate into α-ketoglutarate and alanine. The resulting alanine is transported to the liver where the nitrogen enters the urea cycle and pyruvate is used to produce glucose.
Figure 4: Glucose alanine cycle
Recent studies suggest that pyruvate in high concentrations may play an important role in the treatment of cardiovascular diseases, such as an inotropic agent.
Pyruvate injections or infusions increase the contractile function of hearts by metabolizing glucose or fatty acids. This inotropic effect is striking in ischaemia / reperfusion-stunned hearts.
The inotropic effect of pyruvate requires intracoronary infusion. Among the possible mechanisms for this effect are the increased generation of ATP and an increase in the potential of ATP phosphorylation.
Another mechanism is the activation of pyruvate dehydrogenase, promoting its own oxidation by inhibiting pyruvate dehydrogenase kinase. Pyruvate dehydrogenase is inactivated in myocardial ischemia.
Still another is the reduction of the inorganic cytosolic phosphate concentration. Pyruvate, as an antioxidant, is known to clean reactive oxygen species such as hydrogen peroxide and lipid peroxides. Indirectly, supraphysiological levels of pyruvate may increase cellular reduced glutathione.
Pyruvate is sold as a weight-loss supplement, although there is no evidence to support this use. A systematic review of six trials found a statistically significant difference in body weight with pyruvate compared to placebo.
The review also identified adverse events associated with pyruvate, such as diarrhea, bloating, gas and increased low-density lipoprotein (LDL) cholesterol.
Pyruvic acid-derived bromopyruvic acid is being studied for possible cancer treatment applications by researchers at Johns Hopkins University in ways that support Warburg's hypothesis about the cause or causes of cancer (Pyruvic Acid and Metabolism, S.F.).
References
- Pyruvic Acid and Metabolism. (S.F.). Retrieved from boundless.com.
- EMBL-EBI. (2017, Feb. 27). Pyruvic acid. Retrieved from ebi.ac.uk.
- Human metabolome data base. (2017, March 2). Showing metabocard for Pyruvic acid. Retrieved from hmdb.ca.
- Material Safety Data Sheet Pyruvic acid. (2013, May 21). Retrieved from sciencelab.com.
- Michael Cuffe, e. to. (2016, August 8). Cell BIOLOGY. Retrieved from britannica.com.
- National Center for Biotechnology Information. . (2017, March 11). PubChem Compound Database; CID = 1060. Recovered from PubChem.
- Pyruvic Acid. (1997). Recovered from PubMed.
- Pyruvic acid. (2016, Aug. 17). Retrieved from drugbank.ca.
- Royal Society of Chemistry. (2015). Pyruvic acid. Recovered from chemspider.com.