# Polyene
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{{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](/source/organic_chemistry), '''polyenes''' are [polyunsaturated](/source/saturated_and_unsaturated_compounds) [organic compound](/source/organic_compound)s that contain multiple [carbon–carbon](/source/carbon%E2%80%93carbon_bond) [double bond](/source/double_bond)s ({{chem2|C\dC}}).[{{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}}][{{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}}] Some sources consider [diene](/source/diene)s to be polyenes,[{{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}}][{{BlueBook2013}} [https://iupac.qmul.ac.uk/BlueBook/P1.html#160802 *chapter P1, section P-16.8.2]] whereas others require polyenes to contain three carbon–carbon double bonds ('''trienes''') or more.[{{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}}]
'''Conjugated polyenes''' contain a [conjugated system](/source/conjugated_system) of alternating single and double carbon–carbon bonds, with characteristic [optical properties](/source/optical_properties).
[Annulene](/source/Annulene)s are conjugated cyclopolyenes.
The following polyenes are used as [antifungal](/source/antifungal)s for humans: [amphotericin B](/source/amphotericin_B), [nystatin](/source/nystatin), [candicidin](/source/candicidin), [pimaricin](/source/pimaricin), methyl partricin, and [trichomycin](/source/trichomycin).[{{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}}]
==Optical properties==
Some polyenes are brightly colored, an otherwise rare property for a hydrocarbon. Normally alkenes absorb in the [ultraviolet](/source/ultraviolet) region of a [spectrum](/source/ultraviolet-visible_spectroscopy), 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](/source/chromophore)). Thus many natural [dye](/source/dye)s contain linear polyenes.
==Chemical and electrical properties==
Polyenes tend to be more reactive than simpler alkenes. For example, polyene-containing [triglyceride](/source/triglyceride)s degrade in atmospheric oxygen via the process of [rancidification](/source/rancidification) and [drying](/source/drying_oil). [Polyacetylene](/source/Polyacetylene) exhibits high electrical conductivity in air. Most [conductive polymer](/source/conductive_polymer)s are polyenes, and many have [conjugated](/source/conjugated_system) structures.
==Occurrence==
A few [fatty acid](/source/fatty_acid)s are polyenes. Another class of important polyenes are [polyene antimycotic](/source/polyene_antimycotic)s.[{{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}}]
File:1,3,5-Hexatriene.svg|[1,3,5-Hexatriene](/source/1%2C3%2C5-Hexatriene) is the simplest triene
File:Amphotericin B new.svg|[Amphotericin B](/source/Amphotericin_B) is an example of a [polyene antifungal (antimycotic)](/source/polyene_antimycotic) agent.[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}}.]
File:Leukotriene A4.svg|[Leukotriene](/source/Leukotriene) A4 is a regulator of the immune response.
File:Trans-Polyacetylene.svg|[Polyacetylene](/source/Polyacetylene)s are a synthetic polymer of theoretical interest because they exhibit metallic properties upon oxidation.[Lam, Jacky W. Y.; Tang, Ben Zhong. "Functional Polyacetylenes", Accounts of Chemical Research, 2005, volume 38, pp. 745–754. {{doi|10.1021/ar040012f}}.]
==See also==
* [Polyyne](/source/Polyyne)
==References==
{{Reflist}}
{{Authority control}}
Category:Polyenes
Category:Conjugated hydrocarbons
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Adapted from the Wikipedia article [Polyene](https://en.wikipedia.org/wiki/Polyene) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Polyene?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.