Record Information
Creation date2015-10-09 22:28:34 UTC
Update date2017-01-19 02:36:13 UTC
FoodComEx IDPC000115
FoodDB RecordFDB012586
Chemical Information
NameCitric acid
DescriptionCitric acid (citrate) is a weak tricarboxylic acid that is formed in the tricarboxylic acid cycle. In humans citric acid is produced endogenously or it may be introduced with diet, with citrus fruits being a key source. Citrate is produced by all aerobic organisms, from microbes to humans. Citrate is formed in the TCA cycle via the enzyme known as citrate synthase, which catalyzes the condensation of oxaloacetate with acetyl CoA to form citrate. Citrate then acts as the substrate for aconitase and is converted into aconitic acid. Some bacteria (notably E. coli) can produce and consume citrate internally as part of their TCA cycle, but are unable to use it as food because they lack the enzymes required to import it into the cell. Citrate has a number of biological roles in humans. In particular, it can be transported out of the mitochondria and into the cytoplasm, then broken down into acetyl-CoA for fatty acid synthesis. Citrate can also acts as a signalling molecule. High concentrations of cytosolic citrate can inhibit phosphofructokinase, the catalyst of a rate-limiting step of glycolysis. Inhibition of glycolysis has been shown to suppress tumor growth in a number of animal models ( PMID: 28674429). Citrate is also a vital component of bone, helping to regulate the size of apatite crystals. Urinary citrate levels can be used to identify a number of disorders. Indeed urinary citrate excretion is a common tool in the differential diagnosis of kidney stones, renal tubular acidosis and it plays also a role in characterizing bone diseases such as osteoporosis (PMID 12957820). The secretory epithelial cells of the prostate gland of humans and other animals possess a unique citrate-related metabolic pathway regulated by testosterone and prolactin. This specialized hormone-regulated metabolic activity is responsible for the major prostate function of the production and secretion of extraordinarily high levels of citrate. The key regulatory enzymes directly associated with citrate production in the prostate cells are mitochondrial aspartate aminotransferase, pyruvate dehydrogenase, and mitochondrial aconitase. Testosterone and prolactin are involved in the regulation of the corresponding genes associated with these enzymes (PMID 12198595). In addition to its biological roles and endogenous production, citrate is obtained from many other sources and used in many applications. Citric acid is found in citrus fruits, most concentrated in lemons and limes, where it can comprise as much as 8% of the dry weight of the fruit. The concentrations of citric acid in citrus fruits range from 5 mM for oranges and grapefruits to 300 mM in lemons and limes. However, these values vary within species depending upon the cultivar and the circumstances in which the fruit was grown. Citric acid is a natural preservative and is also used to add an acidic (sour) taste to foods and soft drinks. Citric acid is used as an excipient in pharmaceutical preparations due to its antioxidant properties. It can be used to treat water, which makes it useful in improving the effectiveness of soaps and laundry detergents. Citric acid is also used as an acidulant in creams, gels, and liquids. The salts of citric acid (citrates) can be used as anticoagulants due to their calcium chelating ability. Intolerance to citric acid in the diet is known to exist. Altered levels of citric acid have been found to be associated with maple syrup urine disease, primary hypomagnesemia, propionic acidemia, and tyrosinemia I, which are inborn errors of metabolism.
CAS Number77-92-9
1,2,3-Propanetricarboxylic acid, 2-hydroxy- (9CI)biospider
2-Hydroxy-1,2,3-propanetricarboxylic acidbiospider
2-hydroxypropane-1,2,3-tricarboxylic acidbiospider
2-Hydroxypropanetricarboxylic acidbiospider
2-Hydroxytricarballylic aciddb_source
3-Carboxy-3-hydroxypentane-1,5-dioic acidbiospider
Anhydrous citrateHMDB
Anhydrous citric acidHMDB
beta-Hydroxytricarballylic acidHMDB
e 330HMDB
FEMA 2306db_source
Hydrocerol aHMDB
Kyselina citronovaHMDB
Suby gHMDB
Chemical FormulaC6H8O7
IUPAC name2-hydroxypropane-1,2,3-tricarboxylic acid
InChI IdentifierInChI=1S/C6H8O7/c7-3(8)1-6(13,5(11)12)2-4(9)10/h13H,1-2H2,(H,7,8)(H,9,10)(H,11,12)
Isomeric SMILESOC(=O)CC(O)(CC(O)=O)C(O)=O
Average Molecular Weight192.1235
Monoisotopic Molecular Weight192.02700261
Chemical Taxonomy
Description Belongs to the class of organic compounds known as tricarboxylic acids and derivatives. These are carboxylic acids containing exactly three carboxyl groups.
KingdomOrganic compounds
Super ClassOrganic acids and derivatives
ClassCarboxylic acids and derivatives
Sub ClassTricarboxylic acids and derivatives
Direct ParentTricarboxylic acids and derivatives
Alternative Parents
  • Tricarboxylic acid or derivatives
  • Hydroxy acid
  • Alpha-hydroxy acid
  • Tertiary alcohol
  • Carboxylic acid
  • Organic oxygen compound
  • Organic oxide
  • Hydrocarbon derivative
  • Organooxygen compound
  • Carbonyl group
  • Alcohol
  • Aliphatic acyclic compound
Molecular FrameworkAliphatic acyclic compounds
External Descriptors
Physico-Chemical Properties - Experimental
Experimental logP-1.64AVDEEF,A (1997)
Experimental Water Solubility592 mg/mL at 25 oCYALKOWSKY,SH & HE,Y (2003)
Melting PointMp 153° (anhyd.)DFC
Foods of Origin
FoodContent Range AverageReference
Production Data
Production Methodcommercial
Production Method ReferenceNot Available
Production Method Reference FileNot Available
Quantity AvailableProduction upon request, up to 7 g
Delivery TimeNot Available
Storage Formsolid
Storage Conditions-80°C
StabilityNot Available
PurityNot Available
Spectral Data Upon RequestNot Available
Provider Information
Contact NameContact InstitutionContact Email
Rosa Vazquez
Commercial Vendors
AKSci J92921
AKSci K376
Eastman Chemical Company HMDB0000094
Glentham GV4009
MetaSci HMDB0000094
Toronto Research Chemicals C521000