Lipid of the Month

Each month we highlight a lipid of scientific interest. The LIPID MAPS® Lipid of the Month Archive lists lipids highlighted from 2015 - present.

November 2021

Lipid of the month Capsaicin

Undoubtedly the hottest lipid of the moment is capsaicin- the molecule which imparts the hot sensation we experience when eating chilli peppers and which helped win David Julius this year’s Nobel Prize in Physiology or Medicine. The concentration, and efficacy of these compounds relate to the ‘hotness’ which is measured on the Scoville scale1. Capsaicin acts by stimulating heat receptors and Julius’ team used if to identify which particular protein receptor in sensory neurons it triggered2. The receptor turned out to be TrpV1, a transmembrane protein located in nerve endings. It is also responsible for detecting high temperature. Put your hand in hot water, or a chilli in your mouth and TrpV1 allows cations to flood into the nerve cell, initiating a signal your brain interprets as heat.

Capsaicin, a vanillylamide of 8-methyl-6-nonenoic acid, is very lipophilic, explaining why milk or yoghurt, containing fats, can ease the spiciness of a curry, but water will not. Its presence in peppers deters mammals from eating the fruit and destroying the seeds by chewing them. This strategy might appear to have failed for humans, but serendipitously, our love of chilli means we now cultivate the plants, actively ensuring its genes live on. The avian version of TrpV1 does not react to capsaicin, so birds can eat peppers without the hot taste. They do not digest the seeds but excrete them, with a lump of fertilizer, to grow a new plant. 

While capsaicin causes a sometimes painful burning sensation, and may be responsible for some of the more well-known effects of spicy food3, it can actually be used in the treatment of pain as prolonged exposure desensitizes the receptor such that it can no longer transmit a signal4.

So next time you have a meal containing chillies, remember the capsaicin, a Nobel-esque lipid!

References

  • Note on Capsicums
    J. Am. Pharm. Assoc.
    DOI 10.1002/jps.3080010520
  • The capsaicin receptor: a heat-activated ion channel in the pain pathway
    Nature
    DOI 10.1038/39807
  • Capsaicin—the spicy ingredient of chili peppers: A review of the gastrointestinal effects and mechanisms
    Trends in Food Science & Technology
    DOI 10.1016/j.tifs.2021.08.034
  • Capsaicin: Current Understanding of Its Mechanisms and Therapy of Pain and Other Pre-Clinical and Clinical Uses
    Molecules
    DOI 10.3390/molecules21070844

Lipid of the Month Archive

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2018
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2016
2015