Names | |
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IUPAC name (S)-(β-D-Glucopyranosyloxy)(4-hydroxyphenyl)acetonitrile | |
Systematic IUPAC name (S)-(4-Hydroxyphenyl){[(2R,3R,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)oxan-2-yl]oxy}acetonitrile | |
Other names (S)-4-Hydroxymandelnitrile-β-D-glucopyranoside | |
Identifiers | |
3D model (JSmol) | |
ChemSpider | |
ECHA InfoCard | 100.007.163 |
PubChem CID | |
UNII | |
CompTox Dashboard (EPA) | |
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Properties | |
C14H17NO7 | |
Molar mass | 311.29 g/mol |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
Dhurrin is a cyanogenic glycoside produced in many plants. Discovered in multiple sorghum varieties in 1906 as the culprit of cattle poisoning by hydrogen cyanide, dhurrin is most typically associated with Sorghum bicolor , [1] the organism used for mapping the biosynthesis of dhurrin from tyrosine. Dhurrin's name is derived from the Arabic word for sorghum.
In Sorghum bicolor, dhurrin production is regulated at the transcriptional level and varies depending on the plant’s age and available nutrients. Dhurrin content within S. bicolor can be correlated to the amount of mRNA and translated protein of enzymes CYP79A1 and CYP71E1, two membrane bound members of the cytochrome P450 superfamily. While transcription and translation of these two enzymes is relatively higher for the first few days of growth, transcription is greatly reduced past one week of growth. After five weeks of growth, transcription and translation of both enzymes in the leaves becomes undetectable, while stems in said plants maintain the minimal production of both enzymes. With the addition of excess nitrate, transcription of both enzymes increases, though not to the levels seen in early development. [2] The last enzyme in dhurrin synthesis, UGT85B1, is a soluble enzyme which exchanges glucose from UDP-glucose to the aglycone of dhurrin and forms the glycosidic bond.
Addition of both CYP79A1 and CYP71E1 into the genomes of Arabidopsis thaliana and Nicotiana tabacum has been shown to be sufficient for Dhurrin production to occur. [3] Both of these enzymes are sufficient and necessary for Dhurrin production, as removal of the CYP79A1 gene from the Sorghum bicolor genome results in plants lacking dhurrin content. This strain could theoretically be used as a safer crop for fodder in arid environments where sorghum is the only available grain. In vitro biosynthesis of dhurrin has been constructed in both microsomes recovered from Sorghum bicolor seedlings and in micelles. [4]
Mammalian intestines contain multiple glucosidases which efficiently hydrolyze glycosidic bonds. Upon hydrolysis of the glycosidic bond, the aglycone of dhurrin rapidly degrades to form hydrogen cyanide which is then absorbed into the bloodstream. Lethal dosage of dhurrin in humans and other mammals is theoretically high as one molecule of hydrogen cyanide is produced per molecule of dhurrin. Content of dhurrin by mass in sorghum is relatively low with respect to overall plant matter. As such, it would require a human to eat a considerably large amount of raw sorghum before experiencing adverse effects. In arid environments, sorghum is the best option for cereal grain and fodder as it can withstand extreme drought conditions. [5] Animals consuming the raw sorghum as fodder are much more likely to eat an amount that would contain a lethal dosage of dhurrin for their respective species and can result in animal loss due to hydrogen cyanide poisoning.
In response to external damage to the stem, sorghum varieties can release dhurrin at the damage site. This response has been shown to repel insects as transgenic sorghum made unable to produce dhurrin was heavily favored by herbivorous insects when compared to wild-type sorghum varieties. [6]
In chemistry, a cyanide is a chemical compound that contains a C≡N functional group. This group, known as the cyano group, consists of a carbon atom triple-bonded to a nitrogen atom.
Cytokinins (CK) are a class of plant hormones that promote cell division, or cytokinesis, in plant roots and shoots. They are involved primarily in cell growth and differentiation, but also affect apical dominance, axillary bud growth, and leaf senescence.
Gibberellins (GAs) are plant hormones that regulate various developmental processes, including stem elongation, germination, dormancy, flowering, flower development, and leaf and fruit senescence. GAs are one of the longest-known classes of plant hormone. It is thought that the selective breeding of crop strains that were deficient in GA synthesis was one of the key drivers of the "green revolution" in the 1960s, a revolution that is credited to have saved over a billion lives worldwide.
In chemistry, a glycoside is a molecule in which a sugar is bound to another functional group via a glycosidic bond. Glycosides play numerous important roles in living organisms. Many plants store chemicals in the form of inactive glycosides. These can be activated by enzyme hydrolysis, which causes the sugar part to be broken off, making the chemical available for use. Many such plant glycosides are used as medications. Several species of Heliconius butterfly are capable of incorporating these plant compounds as a form of chemical defense against predators. In animals and humans, poisons are often bound to sugar molecules as part of their elimination from the body.
Cytochromes P450 are a superfamily of enzymes containing heme as a cofactor that mostly, but not exclusively, function as monooxygenases. In mammals, these proteins oxidize steroids, fatty acids, and xenobiotics, and are important for the clearance of various compounds, as well as for hormone synthesis and breakdown. In 1963, Estabrook, Cooper, and Rosenthal described the role of CYP as a catalyst in steroid hormone synthesis and drug metabolism. In plants, these proteins are important for the biosynthesis of defensive compounds, fatty acids, and hormones.
Cytochrome P450 2E1 is a member of the cytochrome P450 mixed-function oxidase system, which is involved in the metabolism of xenobiotics in the body. This class of enzymes is divided up into a number of subcategories, including CYP1, CYP2, and CYP3, which as a group are largely responsible for the breakdown of foreign compounds in mammals.
Cholesterol 7 alpha-hydroxylase also known as cholesterol 7-alpha-monooxygenase or cytochrome P450 7A1 (CYP7A1) is an enzyme that in humans is encoded by the CYP7A1 gene which has an important role in cholesterol metabolism. It is a cytochrome P450 enzyme, which belongs to the oxidoreductase class, and converts cholesterol to 7-alpha-hydroxycholesterol, the first and rate limiting step in bile acid synthesis.
Lotaustralin is a cyanogenic glucoside found in small amounts in Fabaceae austral trefoil, cassava, lima bean, roseroot and white clover, among other plants. Lotaustralin is the glucoside of methyl ethyl ketone cyanohydrin and is structurally related to linamarin, the acetone cyanohydrin glucoside also found in these plants. Both lotaustralin and linamarin may be hydrolyzed by the enzyme linamarase to form glucose and a precursor to the toxic compound hydrogen cyanide.
In enzymology, a 4-hydroxyphenylacetaldehyde oxime monooxygenase (EC 1.14.13.68) is an enzyme that catalyzes the chemical reaction
Cinnamoyl-CoA reductase (EC 1.2.1.44), systematically named cinnamaldehyde:NADP+ oxidoreductase (CoA-cinnamoylating) but commonly referred to by the acronym CCR, is an enzyme that catalyzes the reduction of a substituted cinnamoyl-CoA to its corresponding cinnamaldehyde, utilizing NADPH and H+ and releasing free CoA and NADP+ in the process. Common biologically relevant cinnamoyl-CoA substrates for CCR include p-coumaroyl-CoA and feruloyl-CoA, which are converted into p-coumaraldehyde and coniferaldehyde, respectively, though most CCRs show activity toward a variety of other substituted cinnamoyl-CoA's as well. Catalyzing the first committed step in monolignol biosynthesis, this enzyme plays a critical role in lignin formation, a process important in plants both for structural development and defense response.
In enzymology, a cyanohydrin beta-glucosyltransferase is an enzyme that catalyzes the chemical reaction
(R)-prunasin is a cyanogenic glycoside related to amygdalin. Chemically, it is the glucoside of (R)-mandelonitrile.
Tyrosine N-monooxygenase (EC 1.14.13.41, tyrosine N-hydroxylase, CYP79A1) is an enzyme with systematic name L-tyrosine,NADPH:oxygen oxidoreductase (N-hydroxylating). This enzyme catalyses the following chemical reaction
Isoleucine N-monooxygenase (EC 1.14.13.117, CYP79D3, CYP79D4) is an enzyme with systematic name L-isoleucine,NADPH:oxygen oxidoreductase (N-hydroxylating). This enzyme catalyses the following chemical reaction
Valine N-monooxygenase (EC 1.14.13.118, CYP79D1, CYP79D2) is an enzyme with systematic name L-valine,NADPH:oxygen oxidoreductase (N-hydroxylating). This enzyme catalyses the following chemical reaction
Tryptophan N-monooxygenase (EC 1.14.13.125, tryptophan N-hydroxylase, CYP79B1, CYP79B2, CYP79B3) is an enzyme with systematic name L-tryptophan,NADPH:oxygen oxidoreductase (N-hydroxylating). This enzyme catalyses the following chemical reaction
Colneleate synthase (EC 4.2.1.121, 9-divinyl ether synthase, 9-DES, CYP74D, CYP74D1, CYP74 cytochrome P-450, DES1) is an enzyme with systematic name (8E)-9-((1E,3E)-nona-1,3-dien-1-yloxy)non-8-enoate synthase. This enzyme catalyses the following chemical reaction
Camalexin (3-thiazol-2-yl-indole) is a simple indole alkaloid found in the plant Arabidopsis thaliana and other crucifers. The secondary metabolite functions as a phytoalexin to deter bacterial and fungal pathogens.
Gaseous signaling molecules are gaseous molecules that are either synthesized internally (endogenously) in the organism, tissue or cell or are received by the organism, tissue or cell from outside and that are used to transmit chemical signals which induce certain physiological or biochemical changes in the organism, tissue or cell. The term is applied to, for example, oxygen, carbon dioxide, sulfur dioxide, nitrous oxide, hydrogen cyanide, ammonia, methane, hydrogen, ethylene, etc.
Pisatin (3-hydroxy-7-methoxy-4′,5′-methylenedioxy-chromanocoumarane) is the major phytoalexin made by the pea plant Pisum sativum. It was the first phytoalexin to be purified and chemically identified. The molecular formula is C17H14O6.