Structural characterization of the ligstroside aglycone isoforms in virgin olive oils by liquid ‐chromatography‐high resolution Fourier‐transform mass spectrometry and H/D exchange

AbstractA systematic structural characterization of the isomeric forms related to ligstroside aglycone (LA), one of the most relevant secoiridoids contained in virgin olive oils, was performed using reverse phase liquid chromatography with electrospray ionization Fourier ‐transform single and tandem mass spectrometry, operated in negative ion mode (RPLC‐ESI(‐)‐FTMS and FTMS/MS). The high mass resolution and accuracy provided by the adopted orbital trap mass analyzer enabled the recognition of more than 10 different isomeric forms of LA in virgin olive oil ex tracts. They were related to four different types of molecular structure, two of which including a dihydropyranic ring bearing one or two aldehydic groups, whereas the others corresponded to di‐aldehydic open‐structure forms, differing just for the position of a C=C bond. The contemporary presen ce of (di)enolic tautomers associated to most of these compounds, stable at room temperature (23°C), was also assessed through RPLC‐ESI‐FTMS analyses operated under H/D exchange conditions, i.e. by using D2O instead of H2O as co ‐solvent of acetonitrile in the RPLC mobile phase. As discussed in the paper, the results obtained for LA indicated a remarkable structural similarity with oleuropein aglycone (OA), the most abundant secoiridoid of olive oil, whose isoforms had been previously characterized using the same analytic al approach.

Source: Journal of Mass Spectrometry - September 10, 2019 Category: Chemistry Authors: R. Abbattista, I. Losito, C. De Ceglie, G. Basile, C.D. Calvano, F. Palmisano, T.R.I. Cataldi Tags: RESEARCH ARTICLE Source Type: research