{{short description|Polyunsaturated organic compound}} {{About|the class of chemical compounds|polyenes in antifungal therapy|Polyene antimycotic|the ancient Macedonian writer|Polyaenus}}
In organic chemistry, '''polyenes''' are polyunsaturated organic compounds that contain multiple carbon–carbon double bonds ({{chem2|C\dC}}).<ref name=Penguin2ed>{{cite book |editor-last1=Sharp |editor-first1=DWA |title=The Penguin Dictionary of Chemistry |date=1990 |publisher=Penguin Books |location=London, England; New York, N.Y., USA |isbn=9780140512328 |edition=2nd |page=320 |url=https://archive.org/details/penguindictionar00shar/page/320/mode/2up?q=polyenes}}</ref><ref name=OED2rev>{{cite book |title=Oxford Dictionary of English |date=2005 |publisher=Oxford University Press |location=Oxford; New York |isbn=9780198610571 |edition=2nd, rev |page=1364 |url=https://archive.org/details/oxforddictionary0000unse_z0z2/page/1364/mode/1up?q=polyene}}</ref> Some sources consider dienes to be polyenes,<ref>{{cite book |title=Oxford Dictionary of Biochemistry and Molecular Biology |date=1997 |publisher=Oxford University Press |location=Oxford |isbn=9780198506737 |edition=1st, rev |page=520 |url=https://archive.org/details/isbn_9780198506737/page/n530/mode/1up?q=polyene}}</ref><ref>{{BlueBook2013}} [https://iupac.qmul.ac.uk/BlueBook/P1.html#160802 *chapter P1, section P-16.8.2]</ref> whereas others require polyenes to contain three carbon–carbon double bonds ('''trienes''') or more.<ref name=StructChem>{{cite book |last1=Benet‐Buchholz |first1=Jordi |last2=Boese |first2=Roland |last3=Haumann |first3=Thomas |last4=Traetteberg |first4=Marit |title=The Chemistry of Dienes and Polyenes |chapter=Structural Chemistry of Dienes and Polyenes |date=15 March 1997 |pages=25–65 |doi=10.1002/0470857218.ch2}}</ref>
'''Conjugated polyenes''' contain a conjugated system of alternating single and double carbon–carbon bonds, with characteristic optical properties.
Annulenes are conjugated cyclopolyenes.
The following polyenes are used as antifungals for humans: amphotericin B, nystatin, candicidin, pimaricin, methyl partricin, and trichomycin.<ref>{{cite journal |title=Polyene macrolide antibiotics and their applications in human therapy |author=Zotchev, Sergey B. |journal=Current Medicinal Chemistry |year=2003 |volume=10 |issue=3 |pages=211–223 |doi=10.2174/0929867033368448 |pmid=12570708}}</ref>
==Optical properties== Some polyenes are brightly colored, an otherwise rare property for a hydrocarbon. Normally alkenes absorb in the ultraviolet region of a spectrum, but the absorption energy state of polyenes with numerous conjugated double bonds can be lowered such that they enter the visible region of the spectrum, resulting in compounds which are coloured (because they contain a chromophore). Thus many natural dyes contain linear polyenes.
==Chemical and electrical properties== Polyenes tend to be more reactive than simpler alkenes. For example, polyene-containing triglycerides degrade in atmospheric oxygen via the process of rancidification and drying. Polyacetylene exhibits high electrical conductivity in air. Most conductive polymers are polyenes, and many have conjugated structures.
==Occurrence== A few fatty acids are polyenes. Another class of important polyenes are polyene antimycotics.<ref name="ncbi">{{cite web |url=https://www.ncbi.nlm.nih.gov/books/NBK8263/ |title=Polyene Antifungal Drugs |last=NCBI Bookshelf |date=1996 |publisher=The University of Texas Medical Branch at Galveston |access-date=29 January 2010}}</ref>
<gallery caption="Representative polyenes" widths="170px" heights="112px" class=skin-invert-image> File:1,3,5-Hexatriene.svg|1,3,5-Hexatriene is the simplest triene File:Amphotericin B new.svg|Amphotericin B is an example of a polyene antifungal (antimycotic) agent.<ref>Torrado, J. J.; Espada, R.; Ballesteros, M. P.; Torrado-Santiago, S. "Amphotericin B formulations and drug targeting", Journal of Pharmaceutical Sciences, 2008, volume 97, pp. 2405–2425. {{doi|10.1002/jps.21179}}.</ref> File:Leukotriene A4.svg|Leukotriene A4 is a regulator of the immune response. File:Trans-Polyacetylene.svg|Polyacetylenes are a synthetic polymer of theoretical interest because they exhibit metallic properties upon oxidation.<ref>Lam, Jacky W. Y.; Tang, Ben Zhong. "Functional Polyacetylenes", Accounts of Chemical Research, 2005, volume 38, pp. 745–754. {{doi|10.1021/ar040012f}}.</ref> </gallery>
==See also== * Polyyne
==References== {{Reflist}}
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Category:Polyenes Category:Conjugated hydrocarbons