Lactones are called cyclic esters and are formed when an ester links a hydroxyl group and a carbonyl group within a lactic acid molecule to form a ring structure that is usually pentagonal or hexagonal. They can be sesquiterpenoid (with 15 carbons) or monoterpenoid (with 10 carbons) and play a small part in essential oils and a larger part in herbs.
In essential oils, lactones can be found in very small quantities in both German and Roman Chamomile, Inula, Laurel, and Yarrow, and in larger quantities in Catnip. The small quantity is due to the fact that they are large molecules, so few make it through the distillation process.
We find larger quantities of lactones in herbs. Obviously, they are in the herbs that correspond to the oils listed above, as well as many others including: Arnica, Dandelion, Elecampane, and Lavender (the latter in the form of coumarins).
Lactones are known for being digestive bitters, decongestant, expectorant, and mucolytic. Energetically, they are uplifting, stimulating, and can motivate and inspire. They also have antifungal and antiviral activity. Gamma-lactone causes the milky white color of Dandelion sap. Delta-lactone is very bitter. There are more than 5000 different lactones, and they are responsible for a variety of flavors and fragrances.
Note: Coumarins, which will be discussed next week, are lactones that have undergone further intramolecular reactions.
To learn more abut lactones, check out the chemistry datasheets found in the membership section.
The information contained in this blog is for educational purposes only and has not been evaluated by the Food and Drug Administration.