A Targeted Approach by High Resolution Mass Spectrometry to Reveal New Compounds in Raisins

Abstract

Raisins are dried grapes mostly obtained from cultivars of Vitis vinifera L. and are extensively consumed worldwide. They are rich in bioactive compounds such as polyphenols, which are associated with a broad range of health benefits. The aim of the present study was to compare the phenolic profiles of three different raisin varieties (Thompson seedless, Muscat, and sultanas). Total polyphenols (TPs) were evaluated by the Folin–Ciocalteu (F–C) assay and significant differences were observed among all raisin varieties. Furthermore, liquid chromatography coupled with electrospray ionization hybrid linear ion trap quadrupole-Orbitrap-mass spectrometry (LC/ESI-LTQ-Orbitrap-MS) was employed for the comprehensive identification of phenolic constituents. A total of 45 compounds were identified, including hydroxybenzoic and hydroxycinnamic acids, flavanoids, flavonoids, flavonols, flavones, and stilbenoids. The three varieties of raisins showed a similar phenolic profile, although the highest number of phenolic compounds was identified in Muscat raisins owing to the proanthocyanidins extracted from their seeds, while stilbenoids were not detected in the Thompson variety.

Extraction and Characterization of Bioactive Compounds from Diverse Marine Microalgae and Their Potential Antioxidant Activities

“…Compound 1 , which was detected in P. sulcata and tentatively characterized, was identified as gallic acid based on its observed [M−H] − m / z value of 169.0135. This identification was further confirmed by the product ion at m/z 125, resulting from the loss of carbon dioxide (44 Da) from the precursor ion [27] . Gallic acid is recognized as one of the most abundant phenolic acids and is commonly found in microalgae, either in its free form or as part of dimeric, trimeric, or tetrameric compounds.…”

“…This identification was further confirmed by the product ion at m/z 125, resulting from the loss of carbon dioxide (44 Da) from the precursor ion. [27] Gallic acid is recognized as one of the most abundant phenolic acids and is commonly found in microalgae, either in its free form or as part of dimeric, trimeric, or tetrameric compounds. These gallic acid derivatives can also be esterified with sugar moieties (e. g., glucose) to form hydrolysable tannins, which have been associated with various pharmacological activities.…”

Orange Peel Biomass‐derived Carbon Supported Cu Electrocatalysts Active in the CO2‐Reduction to Formic Acid

“…To rationalize this finding, a preliminary study by liquid chromatography mass spectrometry (LC‐MS) of the aqueous supernatant after the hydrothermal treatment of the peels with or without Cu sulphate indicates not only minor differences in terms of the quantity of ascorbic acid present, which we suggested initially as the primary reducing agent, but also a different composition of other naturally occurring antioxidant constituents (catechins) between the orange peel and the lemon peel. Particularly a component associated to epicatechin [33] is present only in the aqueous supernatant of the orange peel and it is consumed during the hydrothermal synthesis of the Cu NPs (basically in the supernatant when Cu sulphate is also added to the initial suspension), indicating a potential beneficial role of these in the control of the particle size as well as the deoxygenation of the C matrix by these compounds. It means that these antioxidants are released in solution first to reduce the Cu(II) aquo‐sulphate‐complex to from nanoparticles and then adsorb onto them preventing further growth.…”

Exploring the Potential of Vine Shoots as a Source of Valuable Extracts and Stable Lignin Nanoparticles for Multiple Applications

“…Moreover, three B-type procyanidin dimers ( m / z 577) were also identified in both extracts. The unequivocal identification of procyanidins (PAs) was achieved by their characteristic fragmentation (MS 2 ) patterns that include water loss (MS 2 407and 559), heterolytic ring fission (HRF, MS 2 451), quinone methide (QM, MS 2 289) fission, and the retro-Diels-Alder (RDA, MS 2 425) [ 32 , 33 ]. Gallic acid esters of flavan-3-ol and PAS dimers were also identified: (epi)catechin-(epi)catechin gallate ( m / z 729) and a 3-methyl epigallocatechin gallate ( m / z 471).…”