- Surface-active properties of lipophilic antioxidants tyrosol and hydroxytyrosol fatty acid esters: A potential explanation for the nonlinear hypothesis of the antioxidant activity in oil-in-water emulsions
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Our group has recently observed a nonlinear tendency in antioxidant capacity of different hydroxytyrosol fatty acid esters in fish oil-in-water emulsions, where a maximum of antioxidant efficiency appeared for hydroxytyrosol octanoate. These results appea
- Lucas, Ricardo,Comelles, Francisco,Alcantara, David,Maldonado, Olivia S.,Curcuroze, Melanie,Parra, Jose L.,Morales, Juan C.
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- Tyrosol and hydroxytyrosol derivatives as antitrypanosomal and antileishmanial agents
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Trypanosomiasis and leishmaniasis keep being a real challenge for health and development of African countries. Existing treatments have considerable side effects and increase resistance of the parasites. We have measured antitrypanosomal and antileishmanial activity of natural phenols, tyrosol (TYR) and hydroxytyrosol (HT) and several of their esters and metabolites. We found significant IC50 values against Trypanosoma brucei for HT decanoate ester and HT dodecanoate ester (0.6 and 0.36 μM, respectively). This represents a large increase in activity with respect to HT (79 and 132 fold, respectively). Moreover, both compounds displayed a high selectivity index against MRC-5, a non-tumoral human cell line (118 and 106, respectively). Then, we synthesized a focused library of compounds to explore structure-activity. We found the ether and thiourea analogs of HT decanoate ester and HT dodecanoate ester also showed IC50 values against T. brucei in the low micromolar range. In conclusion, the di-ortho phenolic ring and medium size alkyl chain are essential for activity whereas the nature of the chemical bond among them seems less important.
- Belmonte-Reche, Efres,Martínez-García, Marta,Pe?alver, Pablo,Gómez-Pérez, Verónica,Lucas, Ricardo,Gamarro, Francisco,Pérez-Victoria, José María,Morales, Juan Carlos
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p. 132 - 140
(2016/05/24)
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- Cutinase from Fusarium oxysporum catalyzes the acylation of tyrosol in an aqueous medium: Optimization and thermodynamic study of the reaction
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Recently, tyrosol has gained attention as a result of its many pharmacological properties and due to the fact that it can be isolated from cheap and abundant resources. Lipophilic tyrosyl esters, which are scarce in nature, have proven in certain cases to acquire improved biological activity compared to tyrosol itself, increasing their potential use in the food and cosmeceutical industries. The enzymatic approach for the synthesis of such esters has prevailed, as it is "green", compared to chemical practices. We hereby report the enzymatic synthesis of tyrosyl esters of various aliphatic fatty acids performed by a recombinant cutinase from Fusarium oxysporum (FoCut5a). The reaction system used consists of an aqueous phase saturated with the corresponding fatty-acid vinyl ester, which played the role of the acyl donor. We also proceeded to the study of several parameters on the yield of the tyrosyl butyrate ester synthesis. The maximum yield achieved was 60.7% after 4 h at 20 °C, in pH 7.0, with initial tyrosol concentration of 12.5 mM and using 5 μg FoCut5a mL-1 reaction as catalyst. The optimum reaction conditions can be considered mild, highlighting the environmentally friendly nature of this reaction, along with the fact that there are not any harmful reagents involved. Additionally, the use of two thermodynamic models, Conductor-like Screening Model for Real Solvents (COSMO-RS) and UNIquac Functional-group Activity Coefficients (UNIFAC), were employed for the prediction of reactants' and products' solubilities and their distribution in the reaction biphasic system, aiming to correlate the reaction yields with these important thermodynamic quantities and understand the ability of this enzymatic reaction in synthesizing tyrosyl esters.
- Nikolaivits, Efstratios,Norra, Giannis-Florjan,Voutsas, Epaminondas,Topakas, Evangelos
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- Monolayer properties of synthesized tyrosyl esters
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Lipase-catalyzed synthesis of eight fatty acid tyrosyl esters (TyC 2 to TyC18:1) was investigated using non commercial lipases from Rhizopus oryzae and Staphylococcus xylosus immobilized onto CaCO3. The monomolecular film technique was used to compare the ability of the various synthesized tyrosyl fatty acid esters to form a stable monolayer at the air/water interface and their capacity to interact with a phospholipid monolayer. The measurements of surface pressure versus the molecular area shows that, in contrast to tyrosol esterified with short and medium chains (acetic (TyC2), propionic (TyC3), caprylic (TyC8) and capric (TyC10) acids), tyrosol esterified with long chains: lauric (TyC12), palmitic (TyC16), stearic (TyC18) and oleic (TyC18:1) acids are able to form a stable monolayer at the air/water interface. A direct correlation was observed between the length of the saturated acyl chain of the derivatives and their corresponding collapse pressures. The presence of unsaturation reduces the collapse pressure value. The interaction of tyrosyl esters with a phospholipid monolayer was studied and the critical surface pressure (πc) of each ester was determined. Only medium and long chain (TyC8 to TyC18:1) derivatives esters were found to interact efficiently with DiC12PC film.
- Aissa, Imen,Leclaire, Julien,Ali, Yassine Ben,Frikha, Fakher,Gargouri, Youssef
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p. 125 - 130
(2012/11/13)
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