The application of an industrial process based on the hydrothermal treatment of 160 °C/60 min of alperujo, a by-product of olive oil extraction, allows the formation of a liquid phase containing a high concentration of phenolic and secoiridoid compounds. Ethyl acetate was used to extract these phenolic compounds from the aqueous matrix. In this study, the isolation with polyamide and XAD resin allowed detection of the presence of phenolic compounds in minor concentrations. These minor phenols were several oleuropein derivatives that had not been identified in these phenolic extracts previously. The polar compounds, acteosides, secoiridoids, and flavonoids, that remain in the aqueous fraction after extraction with ethyl acetate were identified. We report the presence of known compounds and also detected a novel molecule in alperujo with a molecular weight of 408 whose structure was characterized for first time. This new secoiridoid glucoside was identified as 1-β-D-glucopyranosyl acyclodihydroelenolic acid.
We report the synthesis of acyclic and spiranic imidazole-derived C-selenonucleosides. 5-Hydroxy-4-tetrahydroxybutyl imidazolidine-2-selones, a novel class of acyclic selenonucleosides, were transformed into (tetrahydroxybutylimidazol-2-yl)diselenide, by acetylation and chemoselective N-deacetylation with methanolic imidazole. Furthermore, the synthesis of a new class of conformationally restricted arabinoconfigured spironucleosides containing an imidazolidine-2-
A secoiridoid derivative was isolated
from the ethyl acetate extract
of two-phase olive waste (alperujo). The structure of this compound
was fully characterized as s-trans-(E)-3-(1-oxobut-2-en-2-yl)glutaric acid. The spectroscopic
data, including one- and two-dimensional nuclear magnetic resonance,
mass spectrometry, infrared analysis, and ultraviolet spectrum, were
showed. The origin of this compound has not been previously studied,
although it most likely results from the breakdown of the oleuropein
(or ligstroside) secoiridoid skeleton via oxidation and decarboxylation
of the dialdehydic form of elenolic acid, with this transformation
being enhanced by extraction of phenolics with ethyl acetate. In addition,
the bactericidal activity of (E)-3-(1-oxobut-2-en-2-yl)glutaric
acid and extracts containing it was evaluated against two phytopatoghenic
microorganisms Pseudomonas syringae and Agrobacterium tumefaciens.
Being aware of the enormous biological potential of organoselenium and polyphenolic compounds, we have accomplished the preparation of novel hybrids, combining both pharmacophores in order to obtain new antioxidant and antiproliferative agents. Three different families have been accessed in a straightforward and chemoselective fashion: carbohydrate-containing N-acylisoselenoureas, N-arylisoselenocarbamates and N-arylselenocarbamates. The nature of the organoselenium framework, number and position of phenolic hydroxyl groups and substituents on the aromatic scaffolds afforded valuable structure–activity relationships for the biological assays accomplished: antioxidant properties (antiradical activity, DNA-protective effects, Glutathione peroxidase (GPx) mimicry) and antiproliferative activity. Regarding the antioxidant activity, selenocarbamates 24–27 behaved as excellent mimetics of GPx in the substoichiometric elimination of H2O2 as a Reactive Oxygen Species (ROS) model. Isoselenocarbamates and particularly their selenocarbamate isomers exhibited potent antiproliferative activity against non-small lung cell lines (A549, SW1573) in the low micromolar range, with similar potency to that shown by the chemotherapeutic agent cisplatin (cis-diaminodichloroplatin, CDDP) and occasionally with more potency than etoposide (VP-16).
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