Selemum (Se) and many of its compounds are among the most toxic of nutrients. Selenium toxicity was first described in range animals in the western United States in the 1930's which consumed' selenium accumula...Selemum (Se) and many of its compounds are among the most toxic of nutrients. Selenium toxicity was first described in range animals in the western United States in the 1930's which consumed' selenium accumulator' plants of the genus Astragalus, Xylorrhiza,Oonopsis, and Stanleya. Selenites and selenates from the soil accumulate in these plants primarily as methylated selenium compounds and plants evolve dimethyldiselenide and dimethyselenide.Dietary selenium, primarily as selenomethionine and selenocysteine for humans fulfill the dietary requirement for selenoenzymes and proteins. In humans and animals excessive dietary selenium may be toxic. In vitro, selenium compounds such as selenite, selenium dioxide and diselenides react with thiols, such as glutathione, producing superoxide and other reactive oxygen species. This catalytic reaction of selenium compounds with thiols likely accounts for selenium toxicity to cells ex vivo and in vivo where the major glutathione producing organ,the liver, is also the major target organ of selenium toxicity.Selenium enzymes and selenoethers that do not readily form a selenide (RSe-) anion and compounds such as Ebselen where selenium is sequestered, are not toxic. Methylation of selenium by both plants and animals serves to detoxify selenium by generating methylselenides. Alternatively, full reduction of Se to elemental selenium (Se0) as done by some bacteria and the formation of heavy metal selenides such as Ag2Se or Hg2Se, results in a non-catalytic nontoxic form of selenium.This catalytic prooxidant attribute of some selenium compounds appears to account for its toxicity when such activity exceeds plant and animal methylation reactions and antioxidant defenses. This prooxidant activity may also account for cellular apoptosis and may provide a useful pharmaceutical application for selenium compounds as antibacterial, antiviral, antifungal and anticancer agents展开更多
Natural phenolic compounds are secondary metabolites found in a wide range of plants including food crops. As many of them are known to be antioxidants and can prevent several chronic and degenerative diseases in huma...Natural phenolic compounds are secondary metabolites found in a wide range of plants including food crops. As many of them are known to be antioxidants and can prevent several chronic and degenerative diseases in humans, they are a part of a healthy diet. However, these antioxidants can act as prooxidants under high phenolic concentration, high pH, or in the presence of transition metal ions such as Cu<sup>2+</sup> or Fe<sup>3+</sup>, producing reactive oxygen species (ROS) including hydroxyl radicals resulting in oxidative stress and cell toxicity. While this can lead to pathogenesis including the development of various types of cancers, elevated levels of ROS are beneficial to kill malignant cells and foodborne pathogens to improve food safety. Thus, the dual nature of phenolic compounds allows them to act as antioxidants and prooxidants. Similarly, depending on the level of prooxidant activity, ROS can induce either pathogenesis or serve as a potential agent to kill malignant cells and foodborne pathogens.展开更多
Lactic acid bacteria(LAB)with enhanced oxidative stress tolerance are desirable for probiotic stability and the development of functional foods.In this study,a dual-fortification strategy combining prooxidant stress a...Lactic acid bacteria(LAB)with enhanced oxidative stress tolerance are desirable for probiotic stability and the development of functional foods.In this study,a dual-fortification strategy combining prooxidant stress adap-tation mediated by indicaxanthin with betacyanin surface coating to improve the antioxidant functionality of Lactobacillus bulgaricus ATCC 11842 and Lactococcus lactis subsp.cremoris MG1363 was evaluated.Controlled exposure to indicaxanthin in the presence of a Fe^(2+)catalyst acted as a hormetic trigger,promoting cellular adaptation and leading to a significant increase in oxidative stress tolerance.L.lactis exhibited a stronger adaptive response,reaching 8.70 Log CFU/mL after four stress-recovery cycles,compared to 8.42 Log CFU/mL in L.bulgaricus.When combined with a betanin-rich coating,both strains displayed markedly higher radical-scavenging activity,with dual-fortified cells achieving up to~86%inhibition in DPPH and ABTS assays,out-performing naïve-coated cells.Incorporation of these fortified LAB into yogurt resulted in a dose-dependent enhancement of antioxidant capacity,with the FB+btc(C3 formulation)reaching~80-84%radical reduc-tion.Colorimetric evaluation revealed a clear shift from the achromatic region toward red-magenta hues,reflecting the integration and improved stability of betalain pigments within the dairy matrix.Overall,this work demonstrates that indicaxanthin-driven prooxidant priming,followed by betacyanin coating,yields LAB with superior intrinsic antioxidant defenses and enhances the functional properties and visual color stability of yogurt.This dual-fortification platform offers a promising approach for designing next-generation probiotic foods with improved bioactivity and consumer appeal.展开更多
The methanolic extract of the fresh leaves of khat/Catha edulis was investigated using established procedures for its phytochemical constituents and effect on lipid oxidation.The phytochemical analysis revealed the pr...The methanolic extract of the fresh leaves of khat/Catha edulis was investigated using established procedures for its phytochemical constituents and effect on lipid oxidation.The phytochemical analysis revealed the presence of alkaloids,tannins,phenols,and flavonoids.The effects of the extract on oxidation of locally produced edible NSO(niger seed oil)was assessed through the measurement of peroxide value,iodine value and conjugated diene concentration for a period of sixteen days.Control setup involving NSO without the extract was also kept for the same period of time under similar conditions.It was observed that the peroxide value and conjugated diene value of the oil containing varying concentrations of the extracts of khat leaves increased significantly,relative to the control,showing that the extract of the khat leaves promoted deterioration of the oil.In a similar manner,the iodine value of NSO with and without added khat leaves extract was assessed.It was observed that the iodine value of the oil containing the khat leaves extract decreased more rapidly than the control,suggesting that the double bonds in the fat constituting the oil were diminished by the extract of the khat leaves.It is thus inferred from the present study that methanolic extract of fresh khat leaves leads to deterioration of NSO.It can also be suggested from the results of the present investigation that the health problems khat chewers face may be related to the oxidative damaging effects of these leaves exert on biomolecules found in the body.展开更多
A scheme of the processes in Fenton solution with various substances is offered, and the channels of light formation registered by the luminometer are analyzed. Under the proposed scheme we discuss the possibilities o...A scheme of the processes in Fenton solution with various substances is offered, and the channels of light formation registered by the luminometer are analyzed. Under the proposed scheme we discuss the possibilities of studying the properties of antioxidants and prooxidants. Oxidation of alanine, albumin and sodium oxalate have been taken as an example. The properties of ascorbic acid and the mechanism of display of its oxidant and prooxidant properties are analyzed herewith. Methodical questions of the chemiluminescence research in Fenton solution such as the selection of reagents concentration, water preparation and the effect of the background radiation have been considered in this study as well.展开更多
Leishmaniasis is a dangerous yet neglected tropical disease affecting a vast population of the world.Several medicinal plants and their constituents(natural products/phytochemicals)have been considered of prime import...Leishmaniasis is a dangerous yet neglected tropical disease affecting a vast population of the world.Several medicinal plants and their constituents(natural products/phytochemicals)have been considered of prime importance for the management of leishmaniasis over the years.The present review sheds light on the molecular mechanisms of the constituents obtained from medicinal plants that are pre-clinically effective against leishmaniasis.Various mechanisms by which medicinal plant-derived natural products elicit their action against leishmaniasis are illustrated in the literature.The mechanisms identified include:disruption of cytoplasmic and mitochondrial membranes,induction of apoptosis and autophagy,modulation of gene expression and immunological pathways,pro-oxidant effects(disrupting redox balance)with mitochondrial dysfunction,cell cycle arrest,impaired cellular bioenergetics,i.e.,adenosine triphosphate production and coagulation of cellular contents within Leishmania parasites.Future phytochemical and pharmacological(especially clinical)studies are necessary to further understand the mechanistic details of medicinal plant-derived natural compounds and to develop new phytotherapeutic entities from nature against leishmaniasis.展开更多
Lipoxygenases catalyze the oxidation reaction of fatty acids that have 1,4-Z,Z-pentadiene systems,forming conjugated hydroperoxides as primary products.These enzymes are present in foods participating in oxidative pro...Lipoxygenases catalyze the oxidation reaction of fatty acids that have 1,4-Z,Z-pentadiene systems,forming conjugated hydroperoxides as primary products.These enzymes are present in foods participating in oxidative processes that can lead to organoleptic and nutritional quality spoilage.Therefore,different technological processes have been developed that modulate its pro-oxidant activity by antioxidant addition.As LOX substrates are insoluble in water,its reactions in reversed micelles offer numerous advantages,including the solubilization of both hydrophilic and hydrophobic substrates or products,minimized reaction volumes,a substantial hydrophilic/hydrophobic interfacial area,and control over enzyme activity and stability.The main aims of this work were to evaluate the inhibitory effect of synthetic and natural antioxidants on lipid oxidation catalyzed by lipoxygenase and to determine the kinetic parameters and type of inhibition in reverse micelles for the first time.This biomimetic system water in oil was designed using AOT as the surfactant and linoleic acid as a substrate to measure the enzyme inhibition of a series of phenolic compounds.All these compounds assayed have behavior as mixed non-competitive inhibitors according to linear and non-linear regression methods.The reductions of the catalytic activity of lipoxygenase were between 50% and 70%;besides,the kinetic parameters were also affected by decreasing the Vmax from 266μMs-1 to 217,215,and 101μMs-1 for sinapic acid,propyl gallate,and quercetin,respectively,as the most active inhibitors of the series.Selecting phenolic compounds with strong LOX inhibitory activity maximizes the prevention of lipid oxidation in various food matrices.展开更多
Garlic essential oil(GEO)was added to sunflower oil at different concentrations(0.005%,0.5%,10%)and enriched and non-enriched oils were subjected to accelerated storage(70℃).Oil samples were studied daily by Fourier ...Garlic essential oil(GEO)was added to sunflower oil at different concentrations(0.005%,0.5%,10%)and enriched and non-enriched oils were subjected to accelerated storage(70℃).Oil samples were studied daily by Fourier Transform Mid-Infrared(FTIR)spectroscopy.The changes in the frequency values and absorbance of specific bands of the spectra allowed to shed light on the effect of GEO on oil oxidative stability,in a very simple,fast and accurate way,providing information on the degradation of cis-double bonds of unsaturated acyl groups(band near 3008 cm^(-1)),as well as on the generation of oxidation compounds like hydroperoxides(band near 3469 cm^(-1))and aldehydes(band near 1746 cm^(-1)).Moreover,GEO composition was studied by Proton Nuclear Magnetic Resonance spectroscopy(^(1)H NMR)and by Solid-Phase Microextraction coupled with Gas Chromatography-Mass Spectrometry(SPME-GC/MS).The main GEO components identified were sulphurcontaining compounds(diallyl-disulfide,diallyl-trisulfide,methyl-allyl-disulfide…).The addition of GEO at 0.005% did not affect oil oxidative stability;at 0.5%,it provoked a decrease in oil oxidative stability;and the addition of 10%GEO increased it,causing remarkable differences in the oxidation process compared to the other oils under the same storage conditions.The present study evidences that under accelerated storage conditions the antioxidant efficacy of GEO depends on the concentration added to sunflower oil.This study also underscores the need for careful evaluation of the effect of potential antioxidants,emphasizing the usefulness of FTIR to follow the changes occurring in edible oils during oxidation under accelerated storage conditions.展开更多
文摘Selemum (Se) and many of its compounds are among the most toxic of nutrients. Selenium toxicity was first described in range animals in the western United States in the 1930's which consumed' selenium accumulator' plants of the genus Astragalus, Xylorrhiza,Oonopsis, and Stanleya. Selenites and selenates from the soil accumulate in these plants primarily as methylated selenium compounds and plants evolve dimethyldiselenide and dimethyselenide.Dietary selenium, primarily as selenomethionine and selenocysteine for humans fulfill the dietary requirement for selenoenzymes and proteins. In humans and animals excessive dietary selenium may be toxic. In vitro, selenium compounds such as selenite, selenium dioxide and diselenides react with thiols, such as glutathione, producing superoxide and other reactive oxygen species. This catalytic reaction of selenium compounds with thiols likely accounts for selenium toxicity to cells ex vivo and in vivo where the major glutathione producing organ,the liver, is also the major target organ of selenium toxicity.Selenium enzymes and selenoethers that do not readily form a selenide (RSe-) anion and compounds such as Ebselen where selenium is sequestered, are not toxic. Methylation of selenium by both plants and animals serves to detoxify selenium by generating methylselenides. Alternatively, full reduction of Se to elemental selenium (Se0) as done by some bacteria and the formation of heavy metal selenides such as Ag2Se or Hg2Se, results in a non-catalytic nontoxic form of selenium.This catalytic prooxidant attribute of some selenium compounds appears to account for its toxicity when such activity exceeds plant and animal methylation reactions and antioxidant defenses. This prooxidant activity may also account for cellular apoptosis and may provide a useful pharmaceutical application for selenium compounds as antibacterial, antiviral, antifungal and anticancer agents
文摘Natural phenolic compounds are secondary metabolites found in a wide range of plants including food crops. As many of them are known to be antioxidants and can prevent several chronic and degenerative diseases in humans, they are a part of a healthy diet. However, these antioxidants can act as prooxidants under high phenolic concentration, high pH, or in the presence of transition metal ions such as Cu<sup>2+</sup> or Fe<sup>3+</sup>, producing reactive oxygen species (ROS) including hydroxyl radicals resulting in oxidative stress and cell toxicity. While this can lead to pathogenesis including the development of various types of cancers, elevated levels of ROS are beneficial to kill malignant cells and foodborne pathogens to improve food safety. Thus, the dual nature of phenolic compounds allows them to act as antioxidants and prooxidants. Similarly, depending on the level of prooxidant activity, ROS can induce either pathogenesis or serve as a potential agent to kill malignant cells and foodborne pathogens.
基金supported by grants from ANID/FONDECYT/1250170 and ANID/FOVI/250065.
文摘Lactic acid bacteria(LAB)with enhanced oxidative stress tolerance are desirable for probiotic stability and the development of functional foods.In this study,a dual-fortification strategy combining prooxidant stress adap-tation mediated by indicaxanthin with betacyanin surface coating to improve the antioxidant functionality of Lactobacillus bulgaricus ATCC 11842 and Lactococcus lactis subsp.cremoris MG1363 was evaluated.Controlled exposure to indicaxanthin in the presence of a Fe^(2+)catalyst acted as a hormetic trigger,promoting cellular adaptation and leading to a significant increase in oxidative stress tolerance.L.lactis exhibited a stronger adaptive response,reaching 8.70 Log CFU/mL after four stress-recovery cycles,compared to 8.42 Log CFU/mL in L.bulgaricus.When combined with a betanin-rich coating,both strains displayed markedly higher radical-scavenging activity,with dual-fortified cells achieving up to~86%inhibition in DPPH and ABTS assays,out-performing naïve-coated cells.Incorporation of these fortified LAB into yogurt resulted in a dose-dependent enhancement of antioxidant capacity,with the FB+btc(C3 formulation)reaching~80-84%radical reduc-tion.Colorimetric evaluation revealed a clear shift from the achromatic region toward red-magenta hues,reflecting the integration and improved stability of betalain pigments within the dairy matrix.Overall,this work demonstrates that indicaxanthin-driven prooxidant priming,followed by betacyanin coating,yields LAB with superior intrinsic antioxidant defenses and enhances the functional properties and visual color stability of yogurt.This dual-fortification platform offers a promising approach for designing next-generation probiotic foods with improved bioactivity and consumer appeal.
文摘The methanolic extract of the fresh leaves of khat/Catha edulis was investigated using established procedures for its phytochemical constituents and effect on lipid oxidation.The phytochemical analysis revealed the presence of alkaloids,tannins,phenols,and flavonoids.The effects of the extract on oxidation of locally produced edible NSO(niger seed oil)was assessed through the measurement of peroxide value,iodine value and conjugated diene concentration for a period of sixteen days.Control setup involving NSO without the extract was also kept for the same period of time under similar conditions.It was observed that the peroxide value and conjugated diene value of the oil containing varying concentrations of the extracts of khat leaves increased significantly,relative to the control,showing that the extract of the khat leaves promoted deterioration of the oil.In a similar manner,the iodine value of NSO with and without added khat leaves extract was assessed.It was observed that the iodine value of the oil containing the khat leaves extract decreased more rapidly than the control,suggesting that the double bonds in the fat constituting the oil were diminished by the extract of the khat leaves.It is thus inferred from the present study that methanolic extract of fresh khat leaves leads to deterioration of NSO.It can also be suggested from the results of the present investigation that the health problems khat chewers face may be related to the oxidative damaging effects of these leaves exert on biomolecules found in the body.
文摘A scheme of the processes in Fenton solution with various substances is offered, and the channels of light formation registered by the luminometer are analyzed. Under the proposed scheme we discuss the possibilities of studying the properties of antioxidants and prooxidants. Oxidation of alanine, albumin and sodium oxalate have been taken as an example. The properties of ascorbic acid and the mechanism of display of its oxidant and prooxidant properties are analyzed herewith. Methodical questions of the chemiluminescence research in Fenton solution such as the selection of reagents concentration, water preparation and the effect of the background radiation have been considered in this study as well.
文摘Leishmaniasis is a dangerous yet neglected tropical disease affecting a vast population of the world.Several medicinal plants and their constituents(natural products/phytochemicals)have been considered of prime importance for the management of leishmaniasis over the years.The present review sheds light on the molecular mechanisms of the constituents obtained from medicinal plants that are pre-clinically effective against leishmaniasis.Various mechanisms by which medicinal plant-derived natural products elicit their action against leishmaniasis are illustrated in the literature.The mechanisms identified include:disruption of cytoplasmic and mitochondrial membranes,induction of apoptosis and autophagy,modulation of gene expression and immunological pathways,pro-oxidant effects(disrupting redox balance)with mitochondrial dysfunction,cell cycle arrest,impaired cellular bioenergetics,i.e.,adenosine triphosphate production and coagulation of cellular contents within Leishmania parasites.Future phytochemical and pharmacological(especially clinical)studies are necessary to further understand the mechanistic details of medicinal plant-derived natural compounds and to develop new phytotherapeutic entities from nature against leishmaniasis.
基金financially supported by Projects CICYT-UNSE 23/A301 and PIP 2021-2023 GI-11220200101164CO-CONICET.
文摘Lipoxygenases catalyze the oxidation reaction of fatty acids that have 1,4-Z,Z-pentadiene systems,forming conjugated hydroperoxides as primary products.These enzymes are present in foods participating in oxidative processes that can lead to organoleptic and nutritional quality spoilage.Therefore,different technological processes have been developed that modulate its pro-oxidant activity by antioxidant addition.As LOX substrates are insoluble in water,its reactions in reversed micelles offer numerous advantages,including the solubilization of both hydrophilic and hydrophobic substrates or products,minimized reaction volumes,a substantial hydrophilic/hydrophobic interfacial area,and control over enzyme activity and stability.The main aims of this work were to evaluate the inhibitory effect of synthetic and natural antioxidants on lipid oxidation catalyzed by lipoxygenase and to determine the kinetic parameters and type of inhibition in reverse micelles for the first time.This biomimetic system water in oil was designed using AOT as the surfactant and linoleic acid as a substrate to measure the enzyme inhibition of a series of phenolic compounds.All these compounds assayed have behavior as mixed non-competitive inhibitors according to linear and non-linear regression methods.The reductions of the catalytic activity of lipoxygenase were between 50% and 70%;besides,the kinetic parameters were also affected by decreasing the Vmax from 266μMs-1 to 217,215,and 101μMs-1 for sinapic acid,propyl gallate,and quercetin,respectively,as the most active inhibitors of the series.Selecting phenolic compounds with strong LOX inhibitory activity maximizes the prevention of lipid oxidation in various food matrices.
基金supported by the Basque Government and its Department of Education,Universities and Research(EJ-GV IT1490-22).
文摘Garlic essential oil(GEO)was added to sunflower oil at different concentrations(0.005%,0.5%,10%)and enriched and non-enriched oils were subjected to accelerated storage(70℃).Oil samples were studied daily by Fourier Transform Mid-Infrared(FTIR)spectroscopy.The changes in the frequency values and absorbance of specific bands of the spectra allowed to shed light on the effect of GEO on oil oxidative stability,in a very simple,fast and accurate way,providing information on the degradation of cis-double bonds of unsaturated acyl groups(band near 3008 cm^(-1)),as well as on the generation of oxidation compounds like hydroperoxides(band near 3469 cm^(-1))and aldehydes(band near 1746 cm^(-1)).Moreover,GEO composition was studied by Proton Nuclear Magnetic Resonance spectroscopy(^(1)H NMR)and by Solid-Phase Microextraction coupled with Gas Chromatography-Mass Spectrometry(SPME-GC/MS).The main GEO components identified were sulphurcontaining compounds(diallyl-disulfide,diallyl-trisulfide,methyl-allyl-disulfide…).The addition of GEO at 0.005% did not affect oil oxidative stability;at 0.5%,it provoked a decrease in oil oxidative stability;and the addition of 10%GEO increased it,causing remarkable differences in the oxidation process compared to the other oils under the same storage conditions.The present study evidences that under accelerated storage conditions the antioxidant efficacy of GEO depends on the concentration added to sunflower oil.This study also underscores the need for careful evaluation of the effect of potential antioxidants,emphasizing the usefulness of FTIR to follow the changes occurring in edible oils during oxidation under accelerated storage conditions.
