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Structure of all-trans-lycopene, a pigment that gives the red color to tomatoes. This is not an example of a polyene! All-trans-lycopene is a polyunsaturated isoprenoid.

Polyenes are poly-unsaturated organic compounds that contain at least three alternating double and single carbon–carbon bonds. These carbon–carbon double bonds interact in a process known as conjugation resulting in some unusual optical properties. Related to polyenes are dienes, where there are only two alternating double and single bonds.

The following polyenes are used as antibiotics for humans: amphotericin B, nystatin, candicidin, pimaricin, methyl partricin, and trichomycin.[1]

The polyene carotene is responsible for the orange colour of carrots.

Optical properties[edit]

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, e.g. beta-carotene, which is responsible for the color of carrots.

Chemical and electrical properties[edit]

Polyenes tend to be more reactive than simpler alkenes. For example, polyene-containing triglycerides are reactive towards atmospheric oxygen. Polyacetylene, which partially oxidized or reduced, exhibits high electrical conductivity. Most conductive polymers are polyenes, and many have conjugated structures.


A few fatty acids are polyenes. Another class of important polyenes are polyene antimycotics,[2]


  1. ^ Zotchev, Sergey B. (2003). "Polyene macrolide antibiotics and their applications in human therapy". Current Medicinal Chemistry. 10: 211–223. doi:10.2174/0929867033368448.
  2. ^ NCBI Bookshelf (1996). "Polyene Antifungal Drugs". The University of Texas Medical Branch at Galveston. Retrieved 29 January 2010.
  3. ^ 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
  4. ^ Lam, Jacky W. Y.; Tang, Ben Zhong "Functional Polyacetylenes" Accounts of Chemical Research 2005, volume 38, pp. 745-754. doi:10.1021/ar040012f