oleocanthal

Oleocanthal is a secoiridoid dialdehyde found in freshly pressed extra virgin olive oil, generally considered identical to deacetoxy-ligstroside aglycone. This compound is known to produce a sharp, stinging pungency at the back of the throat when placed in the mouth, a sensation that has been compared to that of an ibuprofen solution. Originally identified independently through two separate methods—fractionation experiments and psychophysical experiments—the compound was named oleocanthal in 2005.

In a study of 12 human subjects, the pungent stinging sensation felt at the front of the tongue when olive oil was placed in the mouth was minimal, whereas strong stinging was reported in the throat. This localization pattern contrasts with allyl isothiocyanate from horseradish, which produces broad stinging throughout the oral cavity.

Research investigating the mechanism of this sensation found that oleocanthal induces current at an EC50 of 2.8 micromolar in cultured cells engineered to express human TRPA1, while it did not activate other channels (TRPV1, TRPV2, TRPV4, TRPM8). Trigeminal neurons from TRPA1-knockout mice did not respond, and blocking TRPA1 eliminated the response in wild-type mice. Experiments with mutant variants also showed that oleocanthal does not use the mechanism typical of electrophilic TRPA1 agonists, which involves covalent binding to specific cysteine residues. However, the actual binding site of oleocanthal on TRPA1 remains unidentified.

In a separate study on bitterness, a trained sensory panel evaluated 200 extra virgin olive oil samples produced across 2 crop seasons, and found that total phenolic content correlated with both bitterness and pungency intensity, although individual phenols differed in their contribution. For bitterness, aglycone isomers of oleuropein and ligstroside accounted for over 70% of discriminating power (ROC analysis), whereas oleocanthal and oleacein were associated with a decrease in bitterness intensity (within the scope of the abstract).