Sesquiterpene lactones (SLs) are a class of sesquiterpenoids that contain a lactone ring. They are most often found in plants of the family Asteraceae (daisies, asters). Other plant families with SLs are Umbelliferae (celery, parsley, carrots) and Magnoliaceae (magnolias). A collection of colorless, lipophilic solids, SLs are a rich source of drugs.^[1] They can be allergenic and toxic in grazing livestock^[2] causing severe neurological problems in horses. Some are also found in corals of the order Alcyonacea.

Sesquiterpene lactones can be divided into several main classes including germacranolides, heliangolides, guaianolides, pseudoguaianolides, hypocretenolides, and eudesmanolides.

Artemisinin, a new, highly-effective anti-malarial compound, is a sesquiterpene lactone found in Artemisia annua. Lactucin, desoxylactucin, lactucopicrin, lactucin-15-oxalate, lactucopicrin-15-oxalate are some of the most prominent found in lettuce and spinach, giving most of the bitter taste to these crops.

One eudesmanolide, 3-oxo-5αH,8βH-eudesma-1,4(15),7(11)-trien-8,12-olide, can work with vernolic acid and other compounds in plants to reduce inflammation.^[3]

Some plants containing these compounds include:

• Artichoke
• Eupatorium^[4]
• Burdock
• Calea ternifolia
• Chamomile
• Chrysanthemum
• Cockleburs
• Feverfew
• Gaillardia
• Ginkgo biloba
• Laurus nobilis^[5]
• Lettuce (Lactuca)
• Mugwort
• Parthenium
• Iva (marsh elders)
• Pyrethrum
• Ragweed
• Sagebrush
• Spinach
• Star anise
• Sunflower
• Vernonia^[6]
• Wormwood
• Yellow star thistle

Quorum sensing inhibitors

Sesquiterpene lactones have been found to possess the ability to inhibit quorum sensing in bacteria.^[7]

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