Beta-hydroxybutyrate

*beta*-Hydroxybutyric acid
Names

IUPAC name 3-Hydroxybutanoic acid
Identifiers
CAS Number	300-85-6^Y
3D model (Jmol)	Interactive image Interactive image
ChEBI	CHEBI:20067^Y
ChEMBL	ChEMBL1162496^Y
ChemSpider	428^Y
ECHA InfoCard	100.005.546
IUPHAR/BPS	1593
MeSH	beta-Hydroxybutyrate
PubChem	441
InChI InChI=1S/C4H8O3/c1-3(5)2-4(6)7/h3,5H,2H2,1H3,(H,6,7)^Y Key: WHBMMWSBFZVSSR-UHFFFAOYSA-N^Y InChI=1/C4H8O3/c1-3(5)2-4(6)7/h3,5H,2H2,1H3,(H,6,7) Key: WHBMMWSBFZVSSR-UHFFFAOYAO
SMILES O=C(O)CC(O)C CC(CC(=O)O)O
Properties
Chemical formula	C₄H₈O₃
Molar mass	104.11 g·mol⁻¹
Appearance	white solid
Melting point	44-46
Related compounds
Other anions	hydroxybutyrate
Related carboxylic acids	propionic acid lactic acid 3-hydroxypropanoic acid malonic acid hydroxypentanoic acid butyric acid β-methylbutyric acid β-hydroxy β-methylbutyric acid
Related compounds	erythrose threose 1,2-butanediol 1,3-butanediol 2,3-butanediol 1,4-butanediol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y (what is ^YN ?)
Infobox references

β-Hydroxybutyric acid, also known as 3-hydroxybutyric acid, is an organic compound and a beta hydroxy acid with the formula CH₃CH(OH)CH₂CO₂H; its conjugate base is beta-hydroxybutyrate, also known as 3-hydroxybutyrate. β-Hydroxybutyric acid is a chiral compound having two enantiomers, D-β-hydroxybutyric acid and L-β-hydroxybutyric acid. Its oxidized and polymeric derivatives occur widely in nature.

In humans, D-3-hydroxybutyrate is synthesized in the liver from acetoacetate, the first ketone produced in the fasting state. The biosynthesis is catalyzed by the enzyme beta-hydroxybutyrate dehydrogenase.

beta-hydroxybutyrate's concentration, as with other ketone bodies, is raised in ketosis. This elevated beta-hydroxybutyrate level is naturally expected, as beta-hydroxybutyrate is formed from acetoacetate. The compound can be used as an energy source by the brain when blood glucose is low.Diabetic patients can have their ketone levels tested via urine or blood to indicate diabetic ketoacidosis. In alcoholic ketoacidosis, this ketone body is produced in greatest concentration. Ketogenesis occurs if oxaloacetate in the liver cells is depleted, a circumstance created by reduced carbohydrate intake (through diet or starvation), prolonged, excessive alcohol consumption, and/or insulin deficiency. Because oxaloacetate is crucial for entry of Acetyl-CoA into the TCA cycle, the rapid production of Acetyl-CoA from fatty acid oxidation in the absence of ample oxaloacetate overwhelms the decreased capacity of the TCA cycle, and the resultant excess of Acetyl-CoA is shunted towards ketone body production.

β-Hydroxybutyric acid is able to cross the blood-brain-barrier into the central nervous system. Levels of β-hydroxybutyric acid increase in the liver, heart, muscle, brain, and other tissues with exercise, calorie restriction, fasting, and ketogenic diets. The compound has been found to act as a histone deacetylase (HDAC) inhibitor. Through inhibition of the HDAC class I isoenzymes HDAC2 and HDAC3, β-hydroxybutyric acid has been found to increase brain-derived neurotrophic factor (BNDF) levels and TrkB signaling in the hippocampus. Moreover, it has been determined that β-hydroxybutyric acid mediates the effects of exercise on BDNF levels in the hippocampus. These findings may have clinical relevance in the treatment of depression, anxiety, and cognitive impairment.

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