The ‘grapefruit effect’ related to an interaction between furanocoumarins – compounds found in the fruit and some other citrus – and certain prescription medications. Furanocoumarins can block the action of a key enzyme critical for the metabolism of the medications, turning a normal dose into a toxic overdose.
“This ‘grapefruit/drug’ interaction has adversely affected the citrus industry for years, even though grapefruit possesses antioxidant activity and numerous beneficial health phytochemicals and putatively acts as a protector against cancer and cardiovascular diseases,” wrote lead author Kyung Myung from the United States Department of Agriculture's Agricultural Research Service.
According to the new research published in the Journal of Agricultural and Food Chemistry, adding the edible fungus Morchella esculenta to grapefruit juice could remove most of the furanocoumarins. And this led to a 60 per cent reduction in the inhibition of one of the enzymes, known as CYP 3A4.
Approximately 70 per cent of the world’s grapefruit production is for the fresh fruit market, while the other 30 per cent goes into the processing industry to give us juice and canned segments. The export market is worth about €200 million, according to FAO estimates.
Dried or live fungi?
Myung and his co-workers Jan Narciso and John Manthey, tested the efficacy of M. esculenta, Monascus purpureus, Pleurotus sapidus, and Agaricus bisporus, all of which are edible fungi, to bind with two of grapefruit’s main furanocoumarins, 6′,7′-dihydroxybergamottin (DHB) and bergamottin (BM).
The report that the when the edible fungi were autoclaved and added to the juice, the furanocoumarins were removed from the juice.
This indicated that the effects were from a general and passive interaction. No effects of the acidity of the juice was observed.
When the researchers tested the efficacy of dried fungal material of M. esculenta, they also observed that the furanocoumarins were removed from the juice, regardless of if the sample had been prepared from fresh grapefruit or from grapefruit juice concentrate.
Furanocoumarin removal approaches
Various scientific approaches have previously been explored to remove furanocoumarins from grapefruit juice, including chemical extractions and reconstitutions, or ultraviolet radiation and heat to degrade the compounds.
Source: Journal of Agricultural and Food Chemistry
Volume 56, Issue 24, Pages 12064-12068, doi: 10.1021/jf802713g
"Removal of Furanocoumarins in Grapefruit Juice by Edible Fungi"
Authors: K. Myung, J.A. Narciso, J.A. Manthey