Oleocanthalic Acid, a Chemical Marker of Olive Oil Aging and Exposure to a High Storage Temperature with Potential Neuroprotective Activity

Abstract

The investigation of olive oils stored for a period of 24 months under appropriate conditions (25 °C, dark place, and airtight container) led to the identification of a new major phenolic ingredient, which was named oleocanthalic acid. The structure of the new compound was elucidated using one- and two-dimensional nuclear magnetic resonance in combination with tandem mass spectrometry. The new compound is an oxidation product of oleocanthal and is found in fresh oils in very low concentrations. The concentration of oleocanthalic acid increased with storage time, while the oleocanthal concentration decreased. A similar increase of the oleocanthalic acid/oleocanthal ratio was achieved after exposure of olive oil to 60 °C for 14 days. Although the presence of an oxidized derivative of decarboxymethylated ligstroside aglycon had been reported, it is the first time that its structure is characterized. The isolated compound could induce the expression of amyloid-β major transport proteins as well as tight junctions expressed at the blood-brain barrier, suggesting that oleocanthalic acid could be beneficial against Alzheimer's disease.

Direct determination of phenolic secoiridoids in olive oil by ultra-high performance liquid chromatography-triple quadruple mass spectrometry analysis

“…On the other hand, oxygenated oleocanthal (oleocanthalic acid 48 ) and oxygenated ligstroside aglycone have the same molecular formula and precursor ion as oleacein and oleuropein aglycone, respectively, but their fragmentation originates different daughter ions 6 . Taxifolin, a phenolic compound of the flavonoid family with the same molecular weight as oleocanthal, can be found in olive oils at <1 mg Kg −1 49 .…”

Effect of Storage Conditions on the Quality of Arbequina Extra Virgin Olive Oil and the Impact on the Composition of Flavor-Related Compounds (Phenols and Volatiles)

“…Oleacein and oleocanthal, with two aldehydic functional groups in an open configuration, possess larger reactivity than monoaldehyde oleuropein aglycone isomers, which are mainly present in a closed configuration [9]. Tsolakou et al [12] has proposed oleocanthalic acid formed by oxidation of oleocanthal as a marker of EVOO aging.…”

Effect of Storage Conditions on the Quality of Arbequina Extra Virgin Olive Oil and the Impact on the Composition of Flavor-related Compounds (Phenols and Volatiles)

“…Oleacein and oleocanthal, with two aldehydic functional groups in an open configuration, possess larger reactivity than monoaldehyde oleuropein aglycone isomers, which are mainly present in a closed configuration [10]. Tsolakou et al [12] has proposed oleocanthalic acid formed by oxidation of oleocanthal as a marker of EVOO ageing.…”

“…Several studies have demonstrated the effects of storage conditions on oil phenols, reporting a decrease in total phenolic content, oxidation of secoiridoid derivatives and increases in hydroxytyrosol and tyrosol, among others [1,[10][11][12][13]. Although a specific phenolic content or composition is not included in the IOC Trade Standard [2], a decrease in its content or significant changes in its composition can affect the stability of olive oils [6,14].…”

“…While several studies have been published on the effects of storage conditions (light, temperature, oxygen, time, type of packaging) on quality of EVOO or VOO [5,[15][16][17][18], few have also focused on the effects of storage conditions on the composition of phenolic or volatile compounds. Moreover, information on the effects of storage conditions on both types of compounds is scarce [10][11][12][13][19][20][21][22][23][24][25][26]. Thus, the aim of this study was to investigate the effects of five storage conditions on the quality parameters of Arbequina variety EVOO, and how these storage conditions impact flavor-related compounds, particularly phenols and volatiles.…”