Difference between revisions of "Butyric acid" - New World Encyclopedia

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Butyric acid


IUPAC name	butyric acid
Identifiers
CAS number	[107-92-6]
PubChem	264
MeSH	Butyric+acid
SMILES	CCCC(=O)O
Properties
Molecular formula	C₄H₈O₂
Molar mass	88.1051
Melting point	-7.9 °C (265.1 K)
Boiling point	163.5 °C (436.5 K)
Hazards
R-phrases	34
S-phrases	26 36 45
Flash point	72 °C
RTECS number	ES5425000
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)

Butyric acid, also known as n-Butanoic acid (in the IUPAC^[1] system) or normal butyric acid, is a carboxylic acid with the structural formula C H₃CH₂CH₂-COOH. It is classified as a short-chain fatty acid. It has an unpleasant odor and acrid taste, but a sweetish aftertaste (similar to ether). It is notably found in rancid butter, parmesan cheese, and vomit. Its name is derived from the Greek word βουτυρος, which means "butter." Certain esters of butyric acid have a pleasant taste or smell, and they are used as additives in foods and perfumes.

Occurrence

Normal butyric acid occurs in the form of esters in animal fats and plant oils. Certain bacteria in the mammalian gut transform highly fermentable fibers—such as oat bran, pectin, and guar—into short chain fatty acids, including butyrate.

The glyceride of butyric acid (that is, its ester with glycerol) makes up 3-4 percent of butter. When butter goes rancid, butyric acid is liberated from the glyceride by hydrolysis, leading to the unpleasant odor.

Normal butyric acid is also found as a hexyl ester in the oil of Heracleum giganteum (cow parsnip) and as an octyl ester in parsnip (Pastinaca sativa). It has also been noticed in the fluids of the flesh and in perspiration.

Preparation

This acid is ordinarily prepared by the fermentation of sugar or starch. The process is carried out by the addition of putrefying cheese, with calcium carbonate added to neutralize the acids formed. The butyric fermentation of starch is aided by the direct addition of Bacillus subtilis.

Notable characteristics

Butyric acid is an oily, colorless liquid that solidifies at -8 °C and boils at 164 °C. It is easily soluble in water, ethanol, and ether, and is thrown out of its aqueous solution by the addition of calcium chloride. The salts and esters of this acid are known as butyrates.

Potassium dichromate and sulfuric acid (or sulphuric acid) oxidize it to carbon dioxide and acetic acid. Alkaline potassium permanganate oxidizes it to carbon dioxide. The calcium salt, Ca(C₄H₇O₂)₂·H₂O, is less soluble in hot water than in cold.

Butyric acid can be detected by mammals with good scent detection abilities (such as dogs) at 10 ppb, while humans can detect it in concentrations above 10 ppm.

An isomer, called isobutyric acid, has the same chemical formula (C₄H₈ O₂) but a different structure. It has similar chemical properties but different physical properties.

Applications

Butyric acid is used in the preparation of various butyrate esters. Low-molecular-weight esters of butyric acid, such as methyl butyrate, have mostly pleasant aromas or tastes. As a consequence, they find use as food and perfume additives. They are also used in organic laboratory courses, to teach the Fisher esterification reaction.

Butyrate fermentation

Butyrate is the end-product of a fermentation process performed by obligate anaerobic bacteria. For instance, kombucha tea contains butyric acid as a result of fermentation. This fermentation pathway was discovered by Louis Pasteur in 1861. Examples of butyrate producing bacterial species are:

Clostridium butyricum
Clostridium kluyveri
Clostridium pasteurianum
Fusobacterium nucleatum
Butyrivibrio fibrisolvens
Eubacterium limosum

Butyric acid function/activity in living organisms

Butyrate has diverse effects on cell proliferation, apoptosis (programmed cell death), and differentiation. Different studies have given contrary results in terms of the effect of butyrate on colon cancer. This lack of agreement (particularly between in vivo and in vitro studies) has been termed the "butyrate paradox."^[2] Collectively, the studies suggest that the cancer preventive benefits of butyrate depend in part on amount, time of exposure (with respect to the tumorigenic process), and the type of fat in the diet. Low carbohydrate diets are known to reduce the amount of butyrate produced in the colon.

Butyric acid has been associated with the ability to inhibit the function of certain (histone deacetylase) enzymes. It is thought that butyric acid enhances the production of RNA from DNA sites (promoters) that are typically silenced/downregulated by the activity of histone deacetylase.

Notes

↑ IUPAC is the acronym for the International Union of Pure and Applied Chemists.
↑ http://jn.nutrition.org/cgi/content/full/134/2/479.

References
ISBN links support NWE through referral fees

McMurry, John. 2004. Organic Chemistry. 6th ed. Belmont, CA: Brooks/Cole. ISBN 0534420052.

Morrison, Robert T., and Robert N. Boyd. 1992. Organic Chemistry. 6th ed. Englewood Cliffs, NJ: Prentice Hall. ISBN 0-13-643669-2.

Solomons, T.W. Graham, and Fryhle, Craig B. 2004. Organic Chemistry. 8th ed. Hoboken, NJ: John Wiley. ISBN 0471417998.

This article incorporates information from the 1911 Encyclopaedia Britannica.

External links

2004 review of the scientific evidence on butyrate vs. colon cancer

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[1] IUPAC is the acronym for the International Union of Pure and Applied Chemists.

[2] ttp://jn.nutrition.org/cgi/content/full/134/2/479.

[1]

[2]

@@ Line 35: / Line 35: @@
 '''Butyric acid''', also known as '''''n''-Butanoic acid''' (in the [[IUPAC]]<ref>IUPAC is the acronym for the International Union of Pure and Applied Chemists.</ref> system) or '''normal butyric acid''', is a [[carboxylic acid]] with the structural formula [[Carbon|C]][[Hydrogen|H]]<sub>3</sub>CH<sub>2</sub>CH<sub>2</sub>-[[Carboxyl group|COOH]]. It is classified as a short-chain [[fatty acid]]. It has an unpleasant odor and acrid taste, but a sweetish aftertaste (similar to [[diethyl ether|ether]]). It is notably found in rancid [[butter]], [[parmesan cheese]],  and [[vomit]]. Its name is derived from the [[Greek language|Greek]] word βουτυρος, which means "butter." Certain [[ester]]s of butyric acid have a pleasant taste or smell, and they are used as additives in foods and perfumes.
-== Occurrence and preparation ==
+== Occurrence ==
-Normal butyric acid occurs in the form of [[esters]] in animal fats and plant oils. The [[glyceride]] of butyric acid makes up 3-4 percent of butter. When butter goes rancid, butyric acid is liberated from the glyceride by [[hydrolysis]], leading to the unpleasant odor.
+Normal butyric acid occurs in the form of [[ester]]s in animal fats and plant oils. Certain [[gut flora|bacteria]] in the [[mammal]]ian gut transform highly fermentable fibers--such as [[oat bran]], [[pectin]], and [[guar]]—into [[short chain fatty acid]]s, including butyrate.
-Normal butyric acid or fermentation butyric acid is also found as a hexyl [[ester]] in the oil of ''Heracleum giganteum'' (cow parsnip) and as an octyl ester in [[parsnip]] ''(Pastinaca sativa)''; it has also been noticed in the fluids of the flesh and in perspiration.
+The [[glyceride]] of butyric acid (that is, its ester with [[glycerol]]) makes up 3-4 percent of butter. When butter goes rancid, butyric acid is liberated from the glyceride by [[hydrolysis]], leading to the unpleasant odor.
-It is ordinarily prepared by the fermentation of [[sugar]] or [[starch]], brought about by the addition of putrefying [[cheese]], with [[calcium carbonate]] added to neutralize the acids formed in the process. The butyric fermentation of starch is aided by the direct addition of ''[[Bacillus subtilis]]''.
+Normal butyric acid is also found as a hexyl [[ester]] in the oil of ''Heracleum giganteum'' (cow parsnip) and as an octyl ester in [[parsnip]] ''(Pastinaca sativa)''. It has also been noticed in the fluids of the flesh and in perspiration.
+== Preparation ==
+This acid is ordinarily prepared by the fermentation of [[sugar]] or [[starch]]. The process is carried out by the addition of putrefying [[cheese]], with [[calcium carbonate]] added to neutralize the acids formed. The butyric fermentation of starch is aided by the direct addition of ''[[Bacillus subtilis]]''.
 == Notable characteristics ==
-Butyric acid is an oily, colorless liquid that solidifies at -8 [[Celsius|°C]] and boils at 164 °C. It is easily soluble in [[water]], [[ethanol]], and [[ether]], and is thrown out of its aqueous solution by the addition of [[calcium chloride]]. [[Potassium dichromate]] and [[sulfuric acid]] (or sulphuric acid) oxidize it to [[carbon dioxide]] and [[acetic acid]]. Alkaline [[potassium permanganate]] oxidizes it to carbon dioxide. The calcium salt, Ca(C<sub>4</sub>H<sub>7</sub>O<sub>2</sub>)<sub>2</sub>·H<sub>2</sub>O, is less soluble in hot water than in cold.
+Butyric acid is an oily, colorless liquid that solidifies at -8 [[Celsius|°C]] and boils at 164 °C. It is easily soluble in [[water]], [[ethanol]], and [[ether]], and is thrown out of its aqueous solution by the addition of [[calcium chloride]]. The salts and esters of this acid are known as ''[[butyrate]]s''.
+[[Potassium dichromate]] and [[sulfuric acid]] (or sulphuric acid) oxidize it to [[carbon dioxide]] and [[acetic acid]]. Alkaline [[potassium permanganate]] oxidizes it to carbon dioxide. The calcium salt, Ca(C<sub>4</sub>H<sub>7</sub>O<sub>2</sub>)<sub>2</sub>·H<sub>2</sub>O, is less soluble in hot water than in cold.
 Butyric acid can be detected by [[mammal]]s with good scent detection abilities (such as [[dog]]s) at 10 [[ppb]], while [[human]]s can detect it in concentrations above 10 [[Parts per million|ppm]].
@@ Line 57: / Line 63: @@
 == Butyrate fermentation ==
-Butyrate is produced as the end-product of a fermentation process solely performed by obligate [[Anaerobic organism|anaerobic]] [[bacteria]]. Kombucha tea includes butyric acid as a result of fermentation. This fermentation pathway was discovered by [[Louis Pasteur]] in 1861. Examples of butyrate producing [[species]] :
+Butyrate is the end-product of a fermentation process performed by obligate [[Anaerobic organism|anaerobic]] [[bacteria]]. For instance, kombucha tea contains butyric acid as a result of fermentation. This fermentation pathway was discovered by [[Louis Pasteur]] in 1861. Examples of butyrate producing bacterial [[species]] are:
 * ''[[Clostridium butyricum]]''
@@ Line 66: / Line 72: @@
 * ''[[Eubacterium limosum]]''
-The pathway starts with the [[glycolysis|glycolytic]] cleavage of [[glucose]] to two [[molecule]]s of [[pyruvate]], as happens in most organisms. Pyruvate is then [[oxidation|oxidized]] into [[acetyl coenzyme A]] using a unique mechanism that involves an [[enzyme]] system called [[pyruvate-ferredoxin oxidoreductase]]. Two molecules of [[carbon dioxide]] (CO<sub>2</sub>) and two molecules of elemental [[hydrogen]] (H<sub>2</sub>) are formed in the process and exit the cell. Then:
+=== Butyric acid function/activity in living organisms ===
-{| class="wikitable"
-| '''Action''' || '''Responsible enzyme'''
- |-
- | Acetyl coenzyme A converts into [[acetoacetyl coenzyme A]] || [[acetyl-CoA-acetyl transferase]]
- |-
- | Acetoacetyl coenzyme A converts into [[β-hydroxybutyryl CoA]] || [[β-hydroxybutyryl-CoA dehydrogenase]]
- |-
- | β-hydroxybutyryl CoA converts into [[crotonyl CoA]] || [[crotonase]]
- |-
- | Crotonyl CoA converts into [[butyryl CoA]] (CH<sub>3</sub>CH<sub>2</sub>CH<sub>2</sub>C=O-CoA) || [[butyryl CoA dehydrogenase]]
- |-
- | A [[phosphate]] group replaces CoA to form [[butyryl phosphate]] || [[phosphobutyrylase]]
- |-
- | The phosphate group joins [[Adenosine diphosphate|ADP]] to form [[Adenosine triphosphate|ATP]] and [[butyrate]] || [[butyrate kinase]]
-|}
-ATP is produced, as can be seen, in the last step of the fermentation. 3 ATPs are produced for each glucose molecule, a relatively high yield. The balanced equation for this fermentation is:
-'''C<sub>6</sub>H<sub>12</sub>O<sub>6</sub> → C<sub>4</sub>H<sub>8</sub>O<sub>2</sub> + 2CO<sub>2</sub> + 2H<sub>2</sub>'''
-=== Acetone and butanol fermentation ===
-Several species form [[acetone]] and [[butanol]] in an alternative pathway which starts as butyrate fermentation. Some of these species are:
-* ''[[Clostridium acetobutylicum]]'': the most prominent acetone and butanol producer, used also industrially
-* ''[[Clostridium beijerinckii]]''
-* ''[[Clostridium tetanomorphum]]''
-* ''[[Clostridium aurantibutyricum]]''
-These bacteria begin with butyrate fermentation as described above, but, when the [[pH]] drops below 5, they switch into butanol and acetone production in order to prevent further lowering of the pH. Two molecules of butanol are formed for each molecule of acetone.
-The change in the pathway occurs after acetoacetyl CoA formation. This intermediate then takes two possible pathways:
-* Acetoacetyl CoA → acetoacetate → acetone, or
-* Acetoacetyl CoA → butyryl CoA → [[butyraldehyde]] → butanol.
-=== Butyric acid function/activity ===
-Highly fermentable fibers like [[oat bran]], [[pectin]], and [[guar]] are transformed by [[gut flora|colonic bacteria]] into [[short chain fatty acids]] including butyrate.
-Butyrate has diverse and apparently paradoxical effects on [[cell growth |cellular proliferation]], [[apoptosis]] and [[cellular differentiation |differentiation]] that may be either pro-neoplastic or anti-neoplastic, depending upon factors such as the level of exposure, availability of other metabolic substrate and the intracellular milieu. Butyrate is thought by some to be protective against [[colon cancer]]. However, not all studies support a chemopreventive effect for butyrate and the lack of agreement (particularly between in vivo and in vitro studies) on butyrate and colon cancer has been termed the "butyrate paradox." There are a number of reasons for this discrepant effect including differences between the in vitro and in vivo environments, the timing of butyrate administration, the amount of butyrate administered, the source of butyrate (usually dietary fiber) as a potential confounder, and an interaction with dietary fat. Collectively, the studies suggest that the chemopreventive benefits of butyrate depend in part on amount, time of exposure with respect to the tumorigenic process, and the type of fat in the diet <ref>http://jn.nutrition.org/cgi/content/full/134/2/479</ref>. Low carbohydrate diets like the [[Atkins diet]] are known to reduce the amount of butyrate produced in the colon.
-Butyric acid has been associated with the ability to inhibit the function of histone deacetylase enzymes, thereby favouring an acetylated state of histones in the cell. Acetylated histones have a lower affinity for DNA than non-acetylated histones, due to the neutralisation of electrostatic charge interections. It is generally thought that [[transcription factors]] will be unable to access regions where histones are tightly associated with DNA (ie non-acetylated, eg heterochromatin). Therefore, it is thought that butyric acid enhances the transcriptional activity at promoters which are typically silenced/downregulated due to histone deacetylase activity.
+Butyrate has diverse effects on [[cell growth|cell proliferation]], [[apoptosis]] (programmed cell death), and [[cellular differentiation |differentiation]]. Different studies have given contrary results in terms of the effect of butyrate on [[colon cancer]]. This lack of agreement (particularly between in vivo and in vitro studies) has been termed the "butyrate paradox."<ref>http://jn.nutrition.org/cgi/content/full/134/2/479.</ref> Collectively, the studies suggest that the cancer preventive benefits of butyrate depend in part on amount, time of exposure (with respect to the tumorigenic process), and the type of fat in the diet. Low carbohydrate diets are known to reduce the amount of butyrate produced in the colon.
-''This article incorporates information from the 1911 encyclopedia.''
+Butyric acid has been associated with the ability to inhibit the function of certain (histone deacetylase) enzymes. It is thought that butyric acid enhances the production of RNA from DNA sites (promoters) that are typically silenced/downregulated by the activity of histone deacetylase.
 == See also ==
@@ Line 130: / Line 94: @@
 * Solomons, T.W. Graham, and Fryhle, Craig B. 2004. ''Organic Chemistry''. 8th ed. Hoboken, NJ: John Wiley. ISBN 0471417998.
+* ''This article incorporates information from the 1911 Encyclopaedia Britannica.''
 ==External links==