Citrus plants produce furanocoumarins as a defense mechanism against herbivorous insects and pathogens. In humans, these chemical compounds function as potent photosensitizers and can interact with medications, leading to the observed "grapefruit juice effect."
Furanocoumarins have the capability to inhibit an enzyme produced by the liver and intestines responsible for metabolizing specific medications in the body. This enzymatic hindrance can result in an increase in medication levels to potentially harmful, even toxic, concentrations.
It's noteworthy that citrus peel contains a more diverse array and higher concentrations of furanocoumarins compared to the pulp of the same fruits. While grapefruit is a well-known source of furanocoumarins, other citrus varieties, such as pomelos (a hybrid of orange and Citrus maxima), Seville oranges (utilized in marmalades), and limes, also contain these compounds. On the other hand, sweet oranges, like navel and Valencia, lack furanocoumarins.
Key furanocoumarins identified in grapefruits include bergamottin, epoxybergamottin, and 6',7'-dihydroxybergamottin.
Furanocoumarins fall into the category of photosensitizers, and their use in cosmetic products is expected to be limited to 1 ppm by the EU. Despite potential restrictions, furanocoumarins retain their therapeutic significance with a variety of clinical applications. They have a historical presence in folk medicine, dating back to the isolation of the first furanocoumarin, 5-methoxypsoralen, by Kalbrunner from bergamot oil in 1838.
Citrus Compounds: Furanocoumarins and Drug Interactions
