Dhurrin: Difference between revisions

| Verifiedfields = changed

| Watchedfields = changed

| verifiedrevid =

|ImageFile=Dhurrin.

|ImageSize=

| (''S'')-(β-<small>D</small>-Glucopyranosyloxy)(4-hydroxyphenyl)acetonitrile

|=(''S'')-(4-Hydroxyphenyl)[(2''R'',3''R'',4''S'',5''S'',6''R'')-3,4,5-trihydroxy-6-(hydroxymethyl)-2-]oxyacetonitrile

| OtherNames=(''S'')-4-Hydroxymandelnitrile-β-<small>D</small>-glucopyranoside

| CASNo_Ref = {{cascite|correct|??}}

| CASNo=499-20-7

| UNII_Ref = {{fdacite|correct|FDA}}

| UNII = P5999IY65C

| PubChem=161355

| SMILES=C1=CC(=CC=C1[C@@H](C#N)O[C@H]2[C@@H]([C@H]([C@@H]([C@H](O2)CO)O)O)O)O

| ChemSpiderID_Ref = {{chemspidercite|changed|chemspider}}

| ChemSpiderID = 141737

| InChI = 1/C14H17NO7/c15-5-9(7-1-3-8(17)4-2-7)21-14-13(20)12(19)11(18)10(6-16)22-14/h1-4,9-14,16-20H,6H2/t9-,10-,11-,12+,13-,14-/m1/s1

| InChIKey = NVLTYOJHPBMILU-YOVYLDAJBT

| StdInChI_Ref = {{stdinchicite|changed|chemspider}}

| StdInChI = 1S/C14H17NO7/c15-5-9(7-1-3-8(17)4-2-7)21-14-13(20)12(19)11(18)10(6-16)22-14/h1-4,9-14,16-20H,6H2/t9-,10-,11-,12+,13-,14-/m1/s1

| StdInChIKey_Ref = {{stdinchicite|changed|chemspider}}

| StdInChIKey = NVLTYOJHPBMILU-YOVYLDAJSA-N

| Formula=C₁₄H₁₇NO₇

| MolarMass=311.29 g/mol

| Appearance=

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'''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]]'',<ref>{{cite book|last1=Blyth|first1=Alexander Wynter|title=Poisons: Their Effects and Detection A Manual for the Use of Analytical Chemists and Experts|date=May 13, 2013|publisher=Charles Griffin and Company|location=USA|page=204}}</ref> the organism used for mapping the [[biosynthesis]] of dhurrin from [[tyrosine]]. Dhurrin's name is derived from the [[Arabic]] word for sorghum.

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===Regulation in ''Sorghum bicolor''===

[[File:Dhurrin Bio Synth.png|thumb|left|alt=A picture showing the enzymatic roles in Dhurrin Synthesis.|Starting with tyrosine, CYP79A1 and CYP71E1 alter the compound before UGT85B1 transfers glucose to form dhurrin.]]

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 (molecular biology)|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.<ref>{{cite journal|last1=Busk|first1=Peter Kamp|title=Dhurrin Synthesis in Sorghum Is Regulated at the Transcriptional Level and Induced by Nitrogen Fertilization in Older Plants|journal=Plant Physiology|date=July 2002|volume=129|issue=3|pages=1222–1231|pmc=166516|doi=10.1104/pp.000687|pmid=12114576}}</ref> 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]].

===Transgenic synthesis===

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.<ref>{{cite journal|last1=Bak|first1=Soren|title=Transgenic Tobacco and Arabidopsis Plants Expressing the Two Multifunctional Sorghum Cytochrome P450 Enzymes, CYP79A1 and CYP71E1, Are Cyanogenic and Accumulate Metabolites Derived from Intermediates in Dhurrin Biosynthesis|journal=Plant Physiology|date=August 2000|volume=123|issue=4|pages=1437–1448|pmc=59100|doi=10.1104/pp.123.4.1437|pmid=10938360}}</ref> 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]].<ref>{{cite journal|last1=Kahn|first1=R A|title=Isolation and reconstitution of cytochrome P450ox and in vitro reconstitution of the entire biosynthetic pathway of the cyanogenic glucoside dhurrin from sorghum.|journal=Plant Physiology|date=December 1997|volume=115|issue=4|pages=1661–1670|pmc=158632|doi=10.1104/pp.115.4.1661|pmid=9414567}}</ref>

==Toxicity==

===Mammals===

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.<ref>{{cite journal|last1=Borrell|first1=Andrew K.|title=Drought adaptation of stay-green sorghum is associated with canopy development, leaf anatomy, root growth, and water uptake|journal=Journal of Experimental Botany|date=2014|volume=65|issue=21|pages=6251–6263|url= |doi=10.1093/jxb/eru232|pmid=25381433|pmc=4223986}}</ref> 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.

===As an insect repellent===

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.<ref>{{cite journal|last1=Krothapalli|first1=Kartikeya|title=Forward Genetics by Genome Sequencing Reveals That Rapid Cyanide Release Deters Insect Herbivory of Sorghum Bicolor|journal=Genetics|date=October 2013|volume=195|issue=2 |pages=309–318|url=http://www.genetics.org/content/195/2/309.full.pdf+html?sid=39121ec4-c3f7-43f8-a7d0-8e5107d03b40|doi=10.1534/genetics.113.149567|pmid=23893483|pmc=3781961}}</ref>

== References ==

<references/>

[[Category:Cyanogenic glycosides]]

[[Category:4-Hydroxyphenyl compounds]]

[[Category:Glucosides]]