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J C Morales - One of the best experts on this subject based on the ideXlab platform.
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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
Journal of Agricultural and Food Chemistry, 2010Co-Authors: Ricardo Lucas, David Alcantara, Francisco Comelles, Olivia S Maldonado, Melanie Curcuroze, Jose Luis Parra, J C MoralesAbstract: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 appear to disagree with the antioxidant polar paradox. Because the physical location of the antioxidants in an oil−water interface has been postulated as an important factor in explaining this behavior, we have prepared a series of tyrosol and Hydroxytyrosol fatty acid esters with different chain length and studied their surface-active properties in water, because these physicochemical parameters could be directly related to the preferential placement at the interface. We have found that tyrosol and Hydroxytyrosol fatty acid esters are relevant surfactants when the right hydrophilic−lipophilic balance (HLB) is attained and, in some cases, as efficient as emulsifiers commonly used in industry, such as Brij 30 or Tween 20. Moreover, a nonlinear dependency of sur...
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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
Journal of Agricultural and Food Chemistry, 2010Co-Authors: Ricardo Lucas, David Alcantara, Francisco Comelles, Olivia S Maldonado, Melanie Curcuroze, Jose Luis Parra, J C MoralesAbstract: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 appear to disagree with the antioxidant polar paradox. Because the physical location of the antioxidants in an oil-water interface has been postulated as an important factor in explaining this behavior, we have prepared a series of tyrosol and Hydroxytyrosol fatty acid esters with different chain length and studied their surface-active properties in water, because these physicochemical parameters could be directly related to the preferential placement at the interface. We have found that tyrosol and Hydroxytyrosol fatty acid esters are relevant surfactants when the right hydrophilic-lipophilic balance (HLB) is attained and, in some cases, as efficient as emulsifiers commonly used in industry, such as Brij 30 or Tween 20. Moreover, a nonlinear dependency of surfactant effectiveness is observed with the increase in chain length of the lipophilic antioxidants. This tendency seems to fit quite well with the reported antioxidant activity in emulsions, and the best antioxidant of the series (Hydroxytyrosol octanoate) is also a very effective surfactant. This potential explanation of the nonlinear hypothesis will help in the rational design of antioxidants used in oil-in-water emulsions.
Ricardo Lucas - One of the best experts on this subject based on the ideXlab platform.
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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
Journal of Agricultural and Food Chemistry, 2010Co-Authors: Ricardo Lucas, David Alcantara, Francisco Comelles, Olivia S Maldonado, Melanie Curcuroze, Jose Luis Parra, J C MoralesAbstract: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 appear to disagree with the antioxidant polar paradox. Because the physical location of the antioxidants in an oil-water interface has been postulated as an important factor in explaining this behavior, we have prepared a series of tyrosol and Hydroxytyrosol fatty acid esters with different chain length and studied their surface-active properties in water, because these physicochemical parameters could be directly related to the preferential placement at the interface. We have found that tyrosol and Hydroxytyrosol fatty acid esters are relevant surfactants when the right hydrophilic-lipophilic balance (HLB) is attained and, in some cases, as efficient as emulsifiers commonly used in industry, such as Brij 30 or Tween 20. Moreover, a nonlinear dependency of surfactant effectiveness is observed with the increase in chain length of the lipophilic antioxidants. This tendency seems to fit quite well with the reported antioxidant activity in emulsions, and the best antioxidant of the series (Hydroxytyrosol octanoate) is also a very effective surfactant. This potential explanation of the nonlinear hypothesis will help in the rational design of antioxidants used in oil-in-water emulsions.
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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
Journal of Agricultural and Food Chemistry, 2010Co-Authors: Ricardo Lucas, David Alcantara, Francisco Comelles, Olivia S Maldonado, Melanie Curcuroze, Jose Luis Parra, J C MoralesAbstract: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 appear to disagree with the antioxidant polar paradox. Because the physical location of the antioxidants in an oil−water interface has been postulated as an important factor in explaining this behavior, we have prepared a series of tyrosol and Hydroxytyrosol fatty acid esters with different chain length and studied their surface-active properties in water, because these physicochemical parameters could be directly related to the preferential placement at the interface. We have found that tyrosol and Hydroxytyrosol fatty acid esters are relevant surfactants when the right hydrophilic−lipophilic balance (HLB) is attained and, in some cases, as efficient as emulsifiers commonly used in industry, such as Brij 30 or Tween 20. Moreover, a nonlinear dependency of sur...
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Effect of Lipophilization of Hydroxytyrosol on Its Antioxidant Activity in Fish Oils and Fish Oil-in-Water Emulsions
Journal of Agricultural and Food Chemistry, 2009Co-Authors: Isabel Medina, Salomé Lois, David Alcantara, Ricardo Lucas, Juan Carlos MoralesAbstract:The effect of lipophilization of the antioxidant efficiency of Hydroxytyrosol on fish oil enriched systems was studied. Hydroxytyrosol fatty acid esters with increasing size of the alkyl chain and different lipophilicity were tested in bulk fish oils and fish oil-in-water emulsions. Results showed a significant antioxidant activity of Hydroxytyrosol esters in both systems especially in emulsions. The introduction of a lipophilic chain decreased the antioxidant effectiveness of Hydroxytyrosol in homogeneous systems as fish oils. In emulsion systems, the presence of a short−medium lipophilic chain (acetate, butyrate or octanoate) improved the antioxidant efficiency of Hydroxytyrosol favoring the physical location of the antioxidant in the interface, but longer alkyl chain (laurate) maintained or even decreased their antioxidant activity. A maximum of antioxidant efficiency seems to appear when the chain length of the Hydroxytyrosol derivative is that of eight carbons which is probably associated with a pref...
Sami Sayadi - One of the best experts on this subject based on the ideXlab platform.
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antidiabetic and antioxidant effects of Hydroxytyrosol and oleuropein from olive leaves in alloxan diabetic rats
Journal of Agricultural and Food Chemistry, 2009Co-Authors: Hedya Jemai, Abdelfattah El Feki, Sami SayadiAbstract:This study was designed to test the antidiabetic and antioxidative activities of olive leaf oleuropein and Hydroxytyrosol. Diabetes in Wistar rats was induced by intraperitoneal injections of alloxan. The serum glucose and cholesterol, hepatic glycogen, the thiobarbituric acid-reactive substances (TBARS), and the components of hepatic and serum antioxidant system were examined. Diabetic rats showed hyperglycemia, hypercholesterolemia, increased lipid peroxidation, and depletion in the antioxidant enzymes activities. The administration, for 4 weeks, of oleuropein and Hydroxytyrosol rich extracts, leading to 8 and 16 mg/kg body weight of each compound, significantly decreased the serum glucose and cholesterols levels and restored the antioxidant perturbations. These results suggested that the antidiabetic effect of oleuropein and Hydroxytyrosol might be due to their antioxidant activities restraining the oxidative stress which is widely associated with diabetes pathologies and complications.
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lipid lowering and antioxidant effects of Hydroxytyrosol and its triacetylated derivative recovered from olive tree leaves in cholesterol fed rats
Journal of Agricultural and Food Chemistry, 2008Co-Authors: Hedya Jemai, Ines Fki, Mohamed Bouaziz, Zouhaier Bouallagui, Abdelfattah El Feki, Hiroko Isoda, Sami SayadiAbstract:This study was designed to test the lipid-lowering and antioxidative activities of triacetylated Hydroxytyrosol compared with its native compound, Hydroxytyrosol, purified from olive tree leaves. Wistar rats fed a standard laboratory diet or a cholesterol-rich diet for 16 weeks were used. The serum lipid levels, the thiobarbituric acid-reactive substances (TBARS) level, as an indicator of lipid peroxidation, and the activity of superoxide dismutase (SOD) as well as that of catalase (CAT) were examined. The cholesterol-rich diet induced hypercholesterolemia that was manifested in the elevation of total cholesterol (TC), triglycerides (TG), and low-density lipoprotein cholesterol (LDL-C). Administration of Hydroxytyrosol and triacetylated Hydroxytyrosol (3 mg/kg of body weight) decreased the serum levels of TC, TG, and LDL-C significantly and increased the serum level of high-density lipoprotein cholesterol (HDL-C). Furthermore, the content of TBARS in liver, heart, kidney, and aorta decreased significantly when Hydroxytyrosol and its triacetylated derivatives were orally administered to rats compared with those fed a cholesterol-rich diet. In addition, triacetylated Hydroxytyrosol and Hydroxytyrosol increased CAT and SOD activities in the liver. These results suggested that the hypolipidemic effect of triacetylated Hydroxytyrosol and Hydroxytyrosol might be due to their abilities to lower serum TC, TG, and LDL-C levels as well as to their antioxidant activities preventing the lipid peroxidation process.
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hypocholesterolemic effects of phenolic extracts and purified Hydroxytyrosol recovered from olive mill wastewater in rats fed a cholesterol rich diet
Journal of Agricultural and Food Chemistry, 2007Co-Authors: Ines Fki, Zouhair Sahnoun, Sami SayadiAbstract:In our previous studies, a phenolic-rich extract of olive mill wastewaters (OMW) was prepared under optimal conditions, using a continuous countercurrent extraction unit, and Hydroxytyrosol was purified from the obtained OMW extract. The antioxidant activity of OMW extract and Hydroxytyrosol was determined by a series of models in vitro. In this study, the hypocholesterolemic effects of Hydroxytyrosol and OMW extract in rats fed a cholesterol-rich diet were tested. Wistar rats, fed a standard laboratory diet or a cholesterol-rich diet for 16 weeks, were used. Serum lipid levels, as well as thiobarbituric acid reactive substances (TBARS) and superoxide dismutase and catalase activities in liver were examined. Cholesterol-rich diet-induced hypercholesterolemia was manifested in the elevation of serum total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C). Administration of a low-dose (2.5 mg/kg of body weight) of Hydroxytyrosol and a high-dose (10 mg/kg of body weight) of OMW extract signifi...
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production of high Hydroxytyrosol yields via tyrosol conversion by pseudomonas aeruginosa immobilized resting cells
Journal of Agricultural and Food Chemistry, 2006Co-Authors: Zouhaie Ouallagui, Sami SayadiAbstract:An immobilized whole cell system was successfully performed to produce the most powerful antioxidant, Hydroxytyrosol. Bioconversion of tyrosol into Hydroxytyrosol was achieved via the immobilization of Pseudomonas aeruginosa resting cells in calcium alginate beads. Immobilization was advantageous as it allows immobilized cells to tolerate a greater tyrosol concentration than free cells. The bioconversion yield reached 86% in the presence of 5 g L-1 of tyrosol when cells immobilized in alginate beads were carried out in single batches. Evaluation of kinetic parameters showed the maintenance of the same catalytic efficiency expressed as Kcat/Km for both free and immobilized cells. The use of immobilized cells in repeated batches demonstrated a notable activity stabilization since the biocatalyst reusability was extended for at least four batches with a molar yield greater than 85%. Keywords: Hydroxytyrosol; bioconversion; Pseudomonas aeruginosa; alginate beads; repeated batch
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use of whole cells of pseudomonas aeruginosa for synthesis of the antioxidant Hydroxytyrosol via conversion of tyrosol
Applied and Environmental Microbiology, 2004Co-Authors: Noureddine Allouche, Mohamed Damak, Radhouane Ellouz, Sami SayadiAbstract:For the first time, a soil bacterium, designated Pseudomonas aeruginosa, was isolated based on its ability to grow on tyrosol as a sole source of carbon and energy. During growth on tyrosol, this strain was capable of promoting the formation of a significant amount of Hydroxytyrosol and trace quantities of parahydroxyphenyl acetic acid and 3,4-dihydroxyphenyl acetic acid. The products were confirmed by high-performance liquid chromatography and gas chromatography-mass spectrometry analyses. Using an optimized tyrosol concentration of 2 g liter−1, the maximal Hydroxytyrosol yield (80%) was achieved after a 7-h reaction in a growth experiment. To enhance the formation of Hydroxytyrosol and prevent its degradation, a resting-cell method using P. aeruginosa was performed. The growth state of the culture utilized for biomass production, the carbon source on which the biomass was grown, the concentration of the biomass, and the amount of tyrosol that was treated were optimized. The optimal yield of Hydroxytyrosol (96%) was obtained after a 7-h reaction using 4 g of tyrosol liter−1 and 5 g of cells liter−1 pregrown on tyrosol and harvested at the end of the exponential phase. This proposed procedure is an alternative approach to obtain Hydroxytyrosol in an environmentally friendly way. In addition, the reaction is easy to perform and can be adapted to a bioreactor for industrial purposes.
David Alcantara - One of the best experts on this subject based on the ideXlab platform.
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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
Journal of Agricultural and Food Chemistry, 2010Co-Authors: Ricardo Lucas, David Alcantara, Francisco Comelles, Olivia S Maldonado, Melanie Curcuroze, Jose Luis Parra, J C MoralesAbstract: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 appear to disagree with the antioxidant polar paradox. Because the physical location of the antioxidants in an oil-water interface has been postulated as an important factor in explaining this behavior, we have prepared a series of tyrosol and Hydroxytyrosol fatty acid esters with different chain length and studied their surface-active properties in water, because these physicochemical parameters could be directly related to the preferential placement at the interface. We have found that tyrosol and Hydroxytyrosol fatty acid esters are relevant surfactants when the right hydrophilic-lipophilic balance (HLB) is attained and, in some cases, as efficient as emulsifiers commonly used in industry, such as Brij 30 or Tween 20. Moreover, a nonlinear dependency of surfactant effectiveness is observed with the increase in chain length of the lipophilic antioxidants. This tendency seems to fit quite well with the reported antioxidant activity in emulsions, and the best antioxidant of the series (Hydroxytyrosol octanoate) is also a very effective surfactant. This potential explanation of the nonlinear hypothesis will help in the rational design of antioxidants used in oil-in-water emulsions.
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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
Journal of Agricultural and Food Chemistry, 2010Co-Authors: Ricardo Lucas, David Alcantara, Francisco Comelles, Olivia S Maldonado, Melanie Curcuroze, Jose Luis Parra, J C MoralesAbstract: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 appear to disagree with the antioxidant polar paradox. Because the physical location of the antioxidants in an oil−water interface has been postulated as an important factor in explaining this behavior, we have prepared a series of tyrosol and Hydroxytyrosol fatty acid esters with different chain length and studied their surface-active properties in water, because these physicochemical parameters could be directly related to the preferential placement at the interface. We have found that tyrosol and Hydroxytyrosol fatty acid esters are relevant surfactants when the right hydrophilic−lipophilic balance (HLB) is attained and, in some cases, as efficient as emulsifiers commonly used in industry, such as Brij 30 or Tween 20. Moreover, a nonlinear dependency of sur...
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Effect of Lipophilization of Hydroxytyrosol on Its Antioxidant Activity in Fish Oils and Fish Oil-in-Water Emulsions
Journal of Agricultural and Food Chemistry, 2009Co-Authors: Isabel Medina, Salomé Lois, David Alcantara, Ricardo Lucas, Juan Carlos MoralesAbstract:The effect of lipophilization of the antioxidant efficiency of Hydroxytyrosol on fish oil enriched systems was studied. Hydroxytyrosol fatty acid esters with increasing size of the alkyl chain and different lipophilicity were tested in bulk fish oils and fish oil-in-water emulsions. Results showed a significant antioxidant activity of Hydroxytyrosol esters in both systems especially in emulsions. The introduction of a lipophilic chain decreased the antioxidant effectiveness of Hydroxytyrosol in homogeneous systems as fish oils. In emulsion systems, the presence of a short−medium lipophilic chain (acetate, butyrate or octanoate) improved the antioxidant efficiency of Hydroxytyrosol favoring the physical location of the antioxidant in the interface, but longer alkyl chain (laurate) maintained or even decreased their antioxidant activity. A maximum of antioxidant efficiency seems to appear when the chain length of the Hydroxytyrosol derivative is that of eight carbons which is probably associated with a pref...
Raquel Mateos - One of the best experts on this subject based on the ideXlab platform.
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antioxidant activity evaluation of alkyl hydroxytyrosyl ethers a new class of Hydroxytyrosol derivatives
Food Chemistry, 2009Co-Authors: Gema Pereiracaro, Jose L Espartero, Arturo Cert, Andres Madrona, Laura Bravo, Felipe Alcudia, Raquel MateosAbstract:Abstract The antioxidant activity of a new series of alkyl hydroxytyrosyl ethers was evaluated by the Rancimat test in a lipophilic food matrix and by the FRAP, ABTS and DPPH assays in a hydrophilic medium, and compared to free Hydroxytyrosol (HTy), butylhydroxytoluene (BHT) and α-tocopherol. All methods used to assess the antioxidant activity of the new compounds emphasised the importance of the ortho-diphenolic structure on the maintenance of the high antioxidant activity associated with free HTy. The results obtained support the ‘polar paradox’ since the antioxidant activity of the lipophilic hydroxytyrosyl ethers was slightly lower in bulk oils and higher in hydrophilic media in comparison with their reference HTy. Although the length of the alkyl chain did not significantly affect the antioxidant activity in bulk oils, it did have a positive influence in hydrophilic medium for ethers with a short alkyl chain (methyl, ethyl and propyl), while ethers with longer alkyl chain (butyl, hexyl, octyl, dodecyl and octadecyl) maintained or even decreased their antioxidant activity, probably due to the steric effect of the side chains. In conclusion, these results show the strong antioxidant activity of a new group of lipophilic HTy derivatives that satisfies the food industry demands for new antioxidants with potential use as functional ingredients to improve the quality and nutritional properties of foods.
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metabolism of the olive oil phenols Hydroxytyrosol tyrosol and hydroxytyrosyl acetate by human hepatoma hepg2 cells
Journal of Agricultural and Food Chemistry, 2005Co-Authors: Raquel Mateos, Luis Goya, Laura AvoAbstract:To study the potential hepatic metabolism of olive oil phenols, human hepatoma HepG2 cells were incubated for 2 and 18 h with Hydroxytyrosol, tyrosol, and hydroxytyrosyl acetate, three phenolic constituents of olive oil. After incubation, culture media and cell lysates were hydrolyzed with beta-glucuronidase and sulfatase and analyzed by LC-MS. In vitro methylation, glucuronidation, and sulfation of pure phenols were also performed. Methylated and glucuronidated forms of Hydroxytyrosol were detected at 18 h of incubation, together with methylglucuronidated metabolites. Hydroxytyrosyl acetate was largely converted into free Hydroxytyrosol and subsequently metabolized, yet small amounts of glucuronidated hydroxytyrosyl acetate were detected. Tyrosol was poorly metabolized, with <10% of the phenol glucuronidated after 18 h. Minor amounts of free or conjugated phenols were detected in cell lysates. No sulfated metabolites were found. In conclusion, olive oil phenols can be metabolized by the liver as suggested by the results obtained using HepG2 cells as a hepatic model system.
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antioxidant effect of phenolic compounds α tocopherol and other minor components in virgin olive oil
Journal of Agricultural and Food Chemistry, 2003Co-Authors: Raquel Mateos, Manuel M Dominguez, Jose L Espartero, Arturo CertAbstract:The effect of acidity, squalene, Hydroxytyrosol, aldehydic form of oleuropein aglycon, hydroxytyrosyl acetate, tyrosol, homovanillic acid, luteolin, apigenin, α-tocopherol, and the mixtures Hydroxytyrosol/hydroxytyrosyl acetate, Hydroxytyrosol/tyrosol, and Hydroxytyrosol/α-tocopherol on the oxidative stability of an olive oil matrix was evaluated. A purified olive oil was spiked with several concentrations of these compounds and, then, subjected to an accelerated oxidation in a Rancimat apparatus at 100 °C. Acidity, squalene, homovanillic acid, and apigenin showed negligible effect. At the same millimolar concentrations, the different o-diphenolic compounds yielded similar and significant increases of the induction time, α-tocopherol a lesser increase, and tyrosol a scarce one. At low concentrations of o-diphenols and α-tocopherol, a linear relationship between induction time and concentration was found, but at high concentrations the induction time tended toward constant values. To explain this behavior,...
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antioxidant effect of phenolic compounds alpha tocopherol and other minor components in virgin olive oil
Journal of Agricultural and Food Chemistry, 2003Co-Authors: Raquel Mateos, Jose L Espartero, M Dominguez, Arturo CertAbstract:The effect of acidity, squalene, Hydroxytyrosol, aldehydic form of oleuropein aglycon, hydroxytyrosyl acetate, tyrosol, homovanillic acid, luteolin, apigenin, alpha-tocopherol, and the mixtures Hydroxytyrosol/hydroxytyrosyl acetate, Hydroxytyrosol/tyrosol, and Hydroxytyrosol/alpha-tocopherol on the oxidative stability of an olive oil matrix was evaluated. A purified olive oil was spiked with several concentrations of these compounds and, then, subjected to an accelerated oxidation in a Rancimat apparatus at 100 degrees C. Acidity, squalene, homovanillic acid, and apigenin showed negligible effect. At the same millimolar concentrations, the different o-diphenolic compounds yielded similar and significant increases of the induction time, alpha-tocopherol a lesser increase, and tyrosol a scarce one. At low concentrations of o-diphenols and alpha-tocopherol, a linear relationship between induction time and concentration was found, but at high concentrations the induction time tended toward constant values. To explain this behavior, a kinetic model was applied. The effect of the mixtures Hydroxytyrosol/hydroxytyrosyl acetate was similar to that of a single o-diphenol at millimolar concentration equal to the sum of millimolar concentrations of both compounds. Concentrations of tyrosol >0.3 mmol/kg increase the induction time by 3 h. The mixtures Hydroxytyrosol/alpha-tocopherol showed opposite effects depending on the relative concentrations of both antioxidants; so, at Hydroxytyrosol concentrations <0.2 mmol/kg, the addition of alpha-tocopherol increased the induction time, whereas at higher Hydroxytyrosol concentrations, the alpha-tocopherol diminished the stability.