| 词条 | Butyric acid | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 释义 |
| Watchedfields = changed | verifiedrevid = 476997169 | ImageFileL1 = Butyric acid acsv.svg | ImageSizeL1 = 100px | ImageNameL1 = Skeletal structure of butyric acid | ImageFileR1 = Butyric_acid_flat_structure.png | ImageSizeR1 = 100px | ImageNameR1 = Flat structure of butyric acid | ImageFile2 = Butyric-acid-3D-balls.png | ImageSize2 = | ImageName2 = Space filling model of butyric acid | PIN = Butanoic acid[1] | OtherNames = Butyric acid[1] 1-Propanecarboxylic acid Propanecarboxylic acid C4:0 (Lipid numbers) |Section1={{Chembox Identifiers | UNII_Ref = {{fdacite|correct|FDA}} | UNII = 40UIR9Q29H | ChEMBL_Ref = {{ebicite|correct|EBI}} | ChEMBL = 14227 | KEGG_Ref = {{keggcite|correct|kegg}} | KEGG = C00246 | InChI = 1/C4H8O2/c1-2-3-4(5)6/h2-3H2,1H3,(H,5,6) | InChIKey = FERIUCNNQQJTOY-UHFFFAOYAP | SMILES1 = CCCC(=O)O | StdInChI_Ref = {{stdinchicite|correct|chemspider}} | StdInChI = 1S/C4H8O2/c1-2-3-4(5)6/h2-3H2,1H3,(H,5,6) | StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} | StdInChIKey = FERIUCNNQQJTOY-UHFFFAOYSA-N | CASNo_Ref = {{cascite|correct|CAS}} | CASNo = 107-92-6 | PubChem = 264 | UNNumber = 2820 | EINECS = 203-532-3 | RTECS = ES5425000 | IUPHAR_ligand = 1059 | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} | ChemSpiderID = 259 | ChEBI_Ref = {{ebicite|correct|EBI}} | ChEBI = 30772 | DrugBank_Ref = {{drugbankcite|correct|drugbank}} | DrugBank = DB03568 | SMILES = O=C(O)CCC | MeSHName = Butyric+acid |Section2={{Chembox Properties | C=4 | H=8 | O=2 | Formula = {{Chem|C|3|H|7|COOH}} | Appearance = Colorless liquid | Odor = Unpleasant, similar to vomit or body odor | Density = 1.135 g/cm3 (−43 °C)[3] 0.9528 g/cm3 (25 °C)[4] | MeltingPtC = −5.1 | MeltingPt_ref = [2] | BoilingPtC = 163.75 | BoilingPt_ref = [2] | SublimationConditions = Sublimes at −35 °C ΔsublH | Solubility = Miscible | SolubleOther = Slightly soluble in CCl4[8] Miscible with ethanol, ether | pKa = 4.82[8] | RefractIndex = 1.398 (20 °C)[2] | Viscosity = 1.814 cP (15 °C)[3] 1.426 cP (25 °C)[8] | VaporPressure = 0.112 kPa (20 °C)[8] 0.74 kPa (50 °C) 9.62 kPa (100 °C)[7] | LogP = 0.79[8] | HenryConstant = 5.35·10−4 L·atm/mol[8] | ThermalConductivity = 1.46·105 W/m·K | MagSus = -55.10·10−6 cm3/mol |Section3={{Chembox Structure | Dipole = 0.93 D (20 °C)[3] | CrystalStruct = Monoclinic (−43 °C)[4] | SpaceGroup = C2/m[4] | LattConst_a = 8.01 Å | LattConst_b = 6.82 Å | LattConst_c = 10.14 Å[4] | LattConst_alpha = | LattConst_beta = 111.45 | LattConst_gamma = |Section4={{Chembox Thermochemistry | HeatCapacity = 178.6 J/mol·K[7][8] | DeltaHf = −533.9 kJ/mol[5] | Entropy = 222.2 J/mol·K[3] | DeltaHc = 2183.5 kJ/mol[5] |Section7={{Chembox Hazards | ExternalSDS = External MSDS| GHSPictograms = {{GHS05}}[6] | GHSSignalWord = Danger | HPhrases = {{H-phrases|314}}[6] | PPhrases = {{P-phrases|280|305+351+338|310}}[6] | FlashPtC = 71 to 72 | FlashPt_ref = [8][6] | AutoignitionPtC = 440 | AutoignitionPt_ref = [6] | ExploLimits = 2.2–13.4%[8] | NFPA-H = 3 | NFPA-F = 2 | NFPA-R = 0 | LD50 = 2000 mg/kg (oral, rat) |Section8={{Chembox Related | OtherAnions = Butyrate | OtherFunction_label = Carboxylic acids | OtherFunction = Propionic acid, Pentanoic acid | OtherCompounds = 1-Butanol Butyraldehyde Methyl butyrate }}Butyric acid (from {{lang-grc|βούτῡρον}}, meaning "butter"), also known under the systematic name butanoic acid,[7] is a carboxylic acid with the structural formula CH3CH2CH2-COOH. Salts and esters of butyric acid are known as butyrates or butanoates. Butyric acid is found in animal fat and plant oils,[7] bovine milk, breast milk,[8] butter, parmesan cheese, and as a product of anaerobic fermentation (including in the colon and as body odor).[7][9] Butyric acid has a taste somewhat like butter and an unpleasant odor.[7] Mammals with good scent detection abilities, such as dogs, can detect it at 10 parts per billion, whereas humans can only detect it in concentrations above 10 parts per million. In food manufacturing, it is used as a flavoring agent.[7] Butyric acid is a biologically active compound in humans.[40] Butyric acid is one of two primary endogenous agonists of human hydroxycarboxylic acid receptor 2 (HCA2), a {{nowrap|Gi/o-coupled}} G protein-coupled receptor.[10][11] ChemistryButyric acid is a fatty acid occurring in the form of esters in animal fats.[7] The triglyceride of butyric acid makes up 3–4% of butter. When butter goes rancid, butyric acid is liberated from the glyceride by hydrolysis, leading to the unpleasant odor.[7] It is one of the fatty acid subgroup called short-chain fatty acids. Butyric acid is a medium-strong acid that reacts with bases and affects many metals.[12] The acid is an oily, colorless liquid that is easily soluble in water, ethanol, and ether, and can be separated from an aqueous phase by saturation with salts such as calcium chloride. It is oxidized to carbon dioxide and acetic acid using potassium dichromate and sulfuric acid, while 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 has a structural isomer called isobutyric acid (2-methylpropanoic acid). SafetyPersonal protective equipment such as rubber or PVC gloves, protective eye goggles, and chemical-resistant clothing and shoes are used to minimize risks when handling butyric acid. Inhalation of butyric acid may result in soreness of throat, coughing, a burning sensation, and laboured breathing. Ingestion of the acid may result in abdominal pain, shock, and collapse. Physical exposure to the acid may result in pain, blistering and skin burns, while exposure to the eyes may result in pain, severe deep burns and loss of vision.[12] HistoryButyric acid was first observed in impure form in 1814 by the French chemist Michel Eugène Chevreul. By 1818, he had purified it sufficiently to characterize it. However, Chevreul did not publish his early research on butyric acid; instead, he deposited his findings in manuscript form with the secretary of the Academy of Sciences in Paris, France. Henri Braconnot, a French chemist, was also researching the composition of butter and was publishing his findings, and this led to disputes about priority. As early as 1815, Chevreul claimed that he had found the substance responsible for the smell of butter.[13] By 1817, he published some of his findings regarding the properties of butyric acid and named it.[14] However, it was not until 1823 that he presented the properties of butyric acid in detail.[15] The name of butyric acid comes from the Latin word for butter, butyrum (or buturum), the substance in which butyric acid was first found.[7] ProductionIndustrially, butyric acid is prepared by fermentation of sugar or starch,[16] made more efficient by use of Clostridium tyrobutyricum in a process called catalytic upgrading.[17] Salts and esters of the acid are called butyrates or butanoates.[7] Butyric acid or fermentation butyric acid is also present as the octyl ester (octyl butyrate) in parsnip (Pastinaca sativa){{citation needed|date=October 2018}} and in the fruit of the ginko tree.[18] UsesButyric 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.[7] As a consequence, they are used as food and perfume additives. It is an approved food flavoring in the EU FLAVIS database (number 08.005). Due to its powerful odor, it has also been used as a fishing bait additive.[19] Many of the commercially available flavors used in carp (Cyprinus carpio) baits use butyric acid as their ester base; however, it is not clear whether fish are attracted by the butyric acid itself or the substances added to it. Butyric acid was, however, one of the few organic acids shown to be palatable for both tench and bitterling.[20] The substance has also been used as a stink bomb by Sea Shepherd Conservation Society to disrupt Japanese whaling crews.[21] Butyric acid, along with acetic acid, can be reacted with cellulose to produce the organic ester cellulose acetate butyrate (CAB), which is used in a wide variety of tools, parts, and coatings, and is more resistant to degradation than cellulose acetate.[22] However, CAB can degrade with exposure to heat and moisture, releasing butyric acid.[23] BiochemistryMicrobial biosynthesis{{missing information|section|date=May 2015|2 additional metabolic pathways: }}Butyrate is produced as end-product of a fermentation process solely performed by obligate anaerobic bacteria. Fermented Kombucha "tea" includes butyric acid as a result of the fermentation. This fermentation pathway was discovered by Louis Pasteur in 1861. Examples of butyrate-producing species of bacteria:
The pathway starts with the glycolytic cleavage of glucose to two molecules of pyruvate, as happens in most organisms. Pyruvate is then oxidized into acetyl coenzyme A using a unique mechanism that involves an enzyme system called ferredoxin oxidoreductase. Two molecules of carbon dioxide (CO2) and two molecules of elemental hydrogen (H2) are formed as waste products from the cell. Then,
ATP is produced, as can be seen, in the last step of the fermentation. Three molecules of ATP are produced for each glucose molecule, a relatively high yield. The balanced equation for this fermentation is C6H12O6 → C4H8O2 + 2 CO2 + 2 H2 Several species form acetone and n-butanol in an alternative pathway, which starts as butyrate fermentation. Some of these species are:
These bacteria begin with butyrate fermentation, as described above, but, when the pH drops below 5, they switch into butanol and acetone production 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:
Fermentable fiber sourcesHighly-fermentable fiber residues, such as those from resistant starch, oat bran, pectin, and guar are transformed by colonic bacteria into short-chain fatty acids (SCFA) including butyrate, producing more SCFA than less fermentable fibers such as celluloses.[9][24] One study found that resistant starch consistently produces more butyrate than other types of dietary fiber.[25] The production of SCFA from fibers in ruminant animals such as cattle is responsible for the butyrate content of milk and butter.[8][26] Fructans are another source of prebiotic soluble dietary fibers which can be digested to produce butyrate. They are often found in the soluble fibers of foods which are high in sulfur, such as the allium and cruciferous vegetables. Sources of fructans include wheat (although some wheat strains such as spelt contain lower amounts),[27] rye, barley, onion, garlic, Jerusalem and globe artichoke, asparagus, beetroot, chicory, dandelion leaves, leek, radicchio, the white part of spring onion, broccoli, brussels sprouts, cabbage, fennel and prebiotics, such as fructooligosaccharides (FOS), oligofructose, and inulin.[28][29] Pharmacology
PharmacodynamicsButyric acid is one of two primary endogenous agonists of human hydroxycarboxylic acid receptor 2 (HCA2, aka GPR109A), a {{nowrap|Gi/o-coupled}} G protein-coupled receptor (GPCR),[10][11] Like other short-chain fatty acids (SCFAs), butyrate is an agonist at the free fatty acid receptors FFAR2 and FFAR3, which function as nutrient sensors that facilitate the homeostatic control of energy balance;[32][74][75] however, among the group of SCFAs, only butyrate is as an agonist of HCA2.[32][74][75] Butyric acid is metabolized by mitochondria, particularly in colonocytes and by the liver, to generate adenosine triphosphate (ATP) during fatty acid metabolism.[32] Butyric acid is also an HDAC inhibitor (specifically, HDAC1, HDAC2, HDAC3, and HDAC8),[30][31] a drug that inhibits the function of histone deacetylase enzymes, thereby favoring an acetylated state of histones in cells.[32] Histone acetylation loosens the structure of chromatin by reducing the electrostatic attraction between histones and DNA.[32] In general, it is thought that transcription factors will be unable to access regions where histones are tightly associated with DNA (i.e., non-acetylated, e.g., heterochromatin).{{mcn|date=October 2016}} Therefore, butyric acid is thought to enhance the transcriptional activity at promoters,[32] which are typically silenced or downregulated due to histone deacetylase activity. PharmacokineticsButyrate that is produced in the colon through microbial fermentation of dietary fiber is primarily absorbed and metabolized by colonocytes and the liver{{#tag:ref|Most of the butyrate that is absorbed into blood plasma from the colon enters the circulatory system via the portal vein;[32] most of the butyrate that enters the circulatory system by this route is taken up by the liver.[32]|group="note"}} for the generation of ATP during energy metabolism;[32] however, some butyrate is absorbed in the distal colon, which is not connected to the portal vein, thereby allowing for the systemic distribution of butyrate to multiple organ systems through the circulatory system.[32] Butyrate that has reached systemic circulation can readily cross the blood-brain barrier via monocarboxylate transporters (i.e., certain members of the SLC16A group of transporters).[33][34] Other transporters that mediate the passage of butyrate across lipid membranes include SLC5A8 (SMCT1), SLC27A1 (FATP1), and SLC27A4 (FATP4).[30][34] Metabolism {{anchor|Butanoate metabolism}}{{expand section|[35]|date=May 2015}}Butyric acid is metabolized by various human XM-ligases (ACSM1, ACSM2B, ASCM3, ACSM4, ACSM5, and ACSM6), also known as butyrate–CoA ligase.[36] The metabolite produced by this reaction is butyryl–CoA, and is produced as follows:[36] Adenosine triphosphate + butyric acid + coenzyme A → adenosine monophosphate + pyrophosphate + butyryl-CoA As a short-chain fatty acid, butyrate is metabolized by mitochondria as an energy (i.e., adenosine triphosphate or ATP) source through fatty acid metabolism. In humans, the butyrate prodrug tributyrin is metabolized by triacylglycerol lipase into dibutyrin and butyrate through the reaction:[37] Tributyrin + H2O → dibutyrin + butyric acid{{clear right}} ResearchPeripheral effectsButyrate has numerous effects on energy homeostasis and related diseases (diabetes and obesity), inflammation, and immune function (e.g., it has pronounced antimicrobial and anticarcinogenic effects) in humans.[38][98] These effects occur through its metabolism by mitochondria to generate {{abbr|ATP|adenosine triphosphate}} during fatty acid metabolism or through one or more of its histone-modifying enzyme targets (i.e., the class I histone deacetylases) and G-protein coupled receptor targets (i.e., FFAR2, FFAR3, and HCA2).[38] Immunomodulation and inflammationButyrate's effects on the immune system are mediated through the inhibition of class I histone deacetylases and activation of its G-protein coupled receptor targets: HCA2 (GPR109A), FFAR2 (GPR43), and FFAR3 (GPR41).[75][101] Among the short-chain fatty acids, butyrate is the most potent promoter of intestinal regulatory T cells in vitro and the only one among the group that is an HCA2 ligand.[75] It has been shown to be a critical mediator of the colonic inflammatory response. It possesses both preventive and therapeutic potential to counteract inflammation-mediated ulcerative colitis and colorectal cancer. Butyrate has established antimicrobial properties in humans that are mediated through the antimicrobial peptide LL-37, which it induces via HDAC inhibition on histone H3.[39][40][41] In vitro, butyrate increases gene expression of FOXP3 (the transcription regulator for {{abbr|Tregs|regulatory T cells}}) and promotes colonic regulatory T cells (Tregs) through the inhibition of class I histone deacetylases;[75][39] through these actions, it increases the expression of interleukin 10, an anti-inflammatory cytokine.[39][42] Butyrate also suppresses colonic inflammation by inhibiting the IFN-γ–STAT1 signaling pathways, which is mediated partially through histone deacetylase inhibition. While transient IFN-γ signaling is generally associated with normal host immune response, chronic IFN-γ signaling is often associated with chronic inflammation. It has been shown that butyrate inhibits activity of HDAC1 that is bound to the Fas gene promoter in T cells, resulting in hyperacetylation of the Fas promoter and up-regulation of Fas receptor on the T-cell surface.[43] Similar to other HCA2 agonists studied, butyrate also produces marked anti-inflammatory effects in a variety of tissues, including the brain, gastrointestinal tract, skin, and vascular tissue.[44][45][46] Butyrate binding at FFAR3 induces neuropeptide Y release and promotes the functional homeostasis of colonic mucosa and the enteric immune system.[47] Butyric acid is an important energy (ATP) source for cells lining the mammalian colon (colonocytes). Without butyric acid for energy, colon cells undergo upregulated autophagy (i.e., self-digestion).[48] CancerButyrate produces different effects in healthy and cancerous cells; this is known as the "butyrate paradox". In particular, butyrate inhibits colonic tumor cells and promotes healthy colonic epithelial cells.[49] The signaling mechanism is not well understood.[50] The production of volatile fatty acids such as butyrate from fermentable fibers may contribute to the role of dietary fiber in colon cancer.[24] Short-chain fatty acids, which include butyric acid, are produced by beneficial colonic bacteria (probiotics) that feed on, or ferment prebiotics, which are plant products that contain dietary fiber. These short-chain fatty acids benefit the colonocytes by increasing energy production and cell proliferation, and may protect against colon cancer.[51] Conversely, some researchers have sought to eliminate butyrate and consider it a potential cancer driver.[52] Studies in mice indicate it drives transformation of MSH2-deficient colon epithelial cells.[53] DiabetesA review on the relationship between the microbiome and diabetes asserted that butyrate can induce "profound immunometabolic effects" in animal models and humans with type 2 diabetes,[54] although there is no such use in clinical practice and further research is needed.{{mcn|date=November 2018}} AddictionButyric acid is an {{abbrlink|HDAC|histone deacetylase}} inhibitor that is selective for class I HDACs in humans.[30] HDACs are histone-modifying enzymes that can cause histone deacetylation and repression of gene expression. HDACs are important regulators of synaptic formation, synaptic plasticity, and long-term memory formation. Several HDACs (specifically, class I HDACs) are known to be involved in mediating the development of an addiction.[55][56][57] Butyric acid and other HDAC inhibitors have been used in preclinical research to assess the transcriptional, neural, and behavioral effects of HDAC inhibition in animals addicted to drugs.[57][58][59] See also
Notes1. ^1 {{cite book | title = Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book) | publisher = The Royal Society of Chemistry | date = 2014 | location = Cambridge | page = 746 | doi = 10.1039/9781849733069-FP001 | isbn = 978-0-85404-182-4| chapter = Front Matter }} 2. ^1 2 3 {{CRC90}} 3. ^1 2 {{cite web|url=http://chemister.ru/Database/properties-en.php?dbid=1&id=1985 |title=butanoic acid |publisher=Chemister.ru |date=2007-03-19 |accessdate=2016-05-09}} 4. ^1 2 3 {{Cite journal | doi = 10.1107/S0365110X6200328X| title = Crystal structure of butyric acid| journal = Acta Crystallographica| volume = 15| issue = 12| pages = 1240–1244| year = 1962| last1 = Strieter | first1 = F. J.| last2 = Templeton | first2 = D. H.| name-list-format = vanc}} 5. ^1 2 3 4 {{nist|name=Butanoic acid| id= C107926|accessdate=13 June 2014|mask=FFFF|units=SI}} 6. ^1 2 3 4 {{Sigma-Aldrich| id= w222119|name=Butyric acid|accessdate=13 June 2014}} 7. ^1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 {{cite web|url=https://pubchem.ncbi.nlm.nih.gov/compound/butyric_acid|title=Butyric acid, PubChem CID 264|publisher=PubChem, US National Library of Medicine|date=24 November 2018|accessdate=29 November 2018}} 8. ^1 {{cite journal|pmc=5748798|year=2017|last1=McNabney|first1=S. M.|title=Short Chain Fatty Acids in the Colon and Peripheral Tissues: A Focus on Butyrate, Colon Cancer, Obesity and Insulin Resistance|journal=Nutrients|volume=9|issue=12|pages=1348|last2=Henagan|first2=T. M.|pmid=29231905|doi=10.3390/nu9121348}} 9. ^1 {{cite journal|pmc=4939913|year=2016|last1=Morrison|first1=D. J.|title=Formation of short chain fatty acids by the gut microbiota and their impact on human metabolism|journal=Gut Microbes|volume=7|issue=3|pages=189–200|last2=Preston|first2=T.|pmid=26963409|doi=10.1080/19490976.2015.1134082}} 10. ^1 {{cite journal | vauthors = Offermanns S, Colletti SL, Lovenberg TW, Semple G, Wise A, IJzerman AP | title = International Union of Basic and Clinical Pharmacology. LXXXII: Nomenclature and Classification of Hydroxy-carboxylic Acid Receptors (GPR81, GPR109A, and GPR109B) | journal = Pharmacological Reviews | volume = 63 | issue = 2 | pages = 269–90 | date = June 2011 | pmid = 21454438 | doi = 10.1124/pr.110.003301 | quote = }} 11. ^1 {{cite web |vauthors = Offermanns S, Colletti SL, IJzerman AP, Lovenberg TW, Semple G, Wise A, Waters MG |title=Hydroxycarboxylic acid receptors |url=http://www.guidetopharmacology.org/GRAC/FamilyDisplayForward?familyId=48 |website=IUPHAR/BPS Guide to Pharmacology |publisher=International Union of Basic and Clinical Pharmacology |accessdate=13 July 2018}} 12. ^1 ICSC 1334 – BUTYRIC ACID. Inchem.org (23 November 1998). Retrieved on 2014-03-31. 13. ^Chevreul (1815) [https://books.google.com/books?id=tZU5AAAAcAAJ&pg=PA73#v=onepage&q&f=false "Lettre de M. Chevreul à MM. les rédacteurs des Annales de chimie"] (Letter from Mr. Chevreul to the editors of the Annals of Chemistry), Annales de chimie, 94 : 73–79; in a footnote spanning pages 75–76, he mentions that he had found a substance that is responsible for the smell of butter. 14. ^Chevreul (1817) [https://books.google.com/books?id=y1E3AAAAYAAJ&pg=PA79#v=onepage&q&f=false "Extrait d'une lettre de M. Chevreul à MM. les Rédacteurs du Journal de Pharmacie"] (Extract of a letter from Mr. Chevreul to the editors of the Journal of Pharmacy), Journal de Pharmacie et des sciences accessoires, 3 : 79–81. On p. 81, he named butyric acid: "Ce principe, que j'ai appelé depuis acid butérique, … " (This principle [i.e., constituent], which I have since named "butyric acid", … ) 15. ^E. Chevreul, Recherches chimiques sur les corps gras d'origine animale [Chemical researches on fatty substances of animal origin] (Paris, France: F.G. 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Lett. | volume = 625 | issue = | pages = 56–63 | date = June 2016 | pmid = 26868600 | pmc = 4903954 | doi = 10.1016/j.neulet.2016.02.009 }} 33. ^{{cite journal | vauthors = Tsuji A | title = Small molecular drug transfer across the blood-brain barrier via carrier-mediated transport systems | journal = NeuroRx | volume = 2 | issue = 1 | pages = 54–62 | year = 2005 | pmid = 15717057 | pmc = 539320 | doi = 10.1602/neurorx.2.1.54 | quote = Other in vivo studies in our laboratories indicated that several compounds including acetate, propionate, butyrate, benzoic acid, salicylic acid, nicotinic acid, and some β-lactam antibiotics may be transported by the MCT at the BBB.21 ... Uptake of valproic acid was reduced in the presence of medium-chain fatty acids such as hexanoate, octanoate, and decanoate, but not propionate or butyrate, indicating that valproic acid is taken up into the brain via a transport system for medium-chain fatty acids, not short-chain fatty acids.}} 34. ^1 {{cite journal | vauthors = Vijay N, Morris ME | title = Role of monocarboxylate transporters in drug delivery to the brain | journal = Curr. Pharm. Des. | volume = 20 | issue = 10 | pages = 1487–98 | year = 2014 | pmid = 23789956 | pmc = 4084603 | doi = 10.2174/13816128113199990462| quote = Monocarboxylate transporters (MCTs) are known to mediate the transport of short chain monocarboxylates such as lactate, pyruvate and butyrate. ... MCT1 and MCT4 have also been associated with the transport of short chain fatty acids such as acetate and formate which are then metabolized in the astrocytes [78]. ... SLC5A8 is expressed in normal colon tissue, and it functions as a tumor suppressor in human colon with silencing of this gene occurring in colon carcinoma. This transporter is involved in the concentrative uptake of butyrate and pyruvate produced as a product of fermentation by colonic bacteria. }} 35. ^{{cite web|title=Butanoate metabolism - Reference pathway|url=http://www.genome.jp/kegg-bin/show_pathway?map00650|website=Kyoto Encyclopedia of Genes and Genomes|publisher=Kanehisa Laboratories|date=1 November 2017|accessdate=1 February 2018}} 36. ^1 {{cite encyclopedia|title=Butyric acid|url=http://www.hmdb.ca/metabolites/HMDB00039|website=Human Metabolome Database|publisher=University of Alberta|accessdate=15 August 2015}} 37. ^{{cite web| title=triacylglycerol lipase – Homo sapiens| url=http://www.brenda-enzymes.org/enzyme.php?ecno=3.1.1.3&Suchword=&organism%5B%5D=Homo+sapiens&show_tm=0| work=BRENDA| publisher=Technische Universität Braunschweig.| accessdate=25 May 2015}} 38. ^1 2 3 {{cite journal | vauthors = Kasubuchi M, Hasegawa S, Hiramatsu T, Ichimura A, Kimura I | title = Dietary gut microbial metabolites, short-chain fatty acids, and host metabolic regulation | journal = Nutrients | volume = 7 | issue = 4 | pages = 2839–49 | year = 2015 | pmid = 25875123 | pmc = 4425176 | doi = 10.3390/nu7042839 | quote = Short-chain fatty acids (SCFAs) such as acetate, butyrate, and propionate, which are produced by gut microbial fermentation of dietary fiber, are recognized as essential host energy sources and act as signal transduction molecules via G-protein coupled receptors (FFAR2, FFAR3, OLFR78, GPR109A) and as epigenetic regulators of gene expression by the inhibition of histone deacetylase (HDAC). Recent evidence suggests that dietary fiber and the gut microbial-derived SCFAs exert multiple beneficial effects on the host energy metabolism not only by improving the intestinal environment, but also by directly affecting various host peripheral tissues.}} 39. ^1 2 3 {{cite journal | vauthors = Wang G | title = Human antimicrobial peptides and proteins | journal = Pharmaceuticals (Basel) | volume = 7 | issue = 5 | pages = 545–94 | year = 2014 | pmid = 24828484 | pmc = 4035769 | doi = 10.3390/ph7050545}} [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4035769/table/pharmaceuticals-07-00545-t003/ Table 3: Select human antimicrobial peptides and their proposed targets] [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4035769/table/pharmaceuticals-07-00545-t004/ Table 4: Some known factors that induce antimicrobial peptide expression] 40. ^{{cite journal | vauthors = Yonezawa H, Osaki T, Hanawa T, Kurata S, Zaman C, Woo TD, Takahashi M, Matsubara S, Kawakami H, Ochiai K, Kamiya S | title = Destructive effects of butyrate on the cell envelope of Helicobacter pylori | journal = J. 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Agents Chemother. | volume = 55 | issue = 6 | pages = 2897–904 | year = 2011 | pmid = 21464244 | pmc = 3101455 | doi = 10.1128/AAC.00016-11 | url = }} 42. ^1 2 3 4 5 {{cite journal | vauthors = Hoeppli RE, Wu D, Cook L, Levings MK | title = The environment of regulatory T cell biology: cytokines, metabolites, and the microbiome | journal = Front Immunol | volume = 6 | issue = | page = 61 | date = February 2015 | pmid = 25741338 | pmc = 4332351 | doi = 10.3389/fimmu.2015.00061}} [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4332351/figure/F1/ Figure 1: Microbial-derived molecules promote colonic Treg differentiation.] 43. ^{{cite journal | vauthors = Zimmerman MA, Singh N, Martin PM, Thangaraju M, Ganapathy V, Waller JL, Shi H, Robertson KD, Munn DH, Liu K | title = Butyrate suppresses colonic inflammation through HDAC1-dependent Fas upregulation and Fas-mediated apoptosis of T cells | journal = Am. J. Physiol. Gastrointest. 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7 : GABA analogues|Flavors|Alkanoic acids|Fatty acids|Foul-smelling chemicals|Biomolecules|Histone deacetylase inhibitors |
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