Mycotoxin sequestration materials are important tools to reduce mycotoxin illness and enable prop... more Mycotoxin sequestration materials are important tools to reduce mycotoxin illness and enable proper handling of mycotoxin-contaminated commodities. Three food-grade bentonite clays and four generally recognized as safe (GRAS) charcoal/biochar carbon materials that are marketed as feed additives and supplements were evaluated for their ability to sequester the mycotoxins aflatoxin B1, ochratoxin A, and zearalenone. The surface area of the clays varied between 32.1 to 51.4 mg2/g, and the surface area of the carbon-based materials varied from 1.7 to 1735 mg2/g. In vitro, gastric fluid studies indicated that certain pine biochar and activated coconut charcoal could sequester high amounts (85+%) of the mycotoxins at 1 ppm levels or below. However, some biochar materials with lower surface area properties lacked binding capacity. The coconut shell charcoal and pine biochar utilize agricultural waste products in a manner that significantly reduces carbon emissions and provides valuable mat...
Predictive models were developed using two-dimensional quantitative structure activity relationsh... more Predictive models were developed using two-dimensional quantitative structure activity relationship (QSAR) methods coupled with B3LYP/6-311+G** density functional theory modeling that describe the antimicrobial properties of twenty-four triazolothiadiazine compounds against Aspergillus niger, Aspergillus flavus and Penicillium sp., as well as the bacteria Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa. B3LYP/6-311+G** density functional theory calculations indicated the triazolothiadiazine derivatives possess only modest variation between the frontier orbital properties. Genetic function approximation (GFA) analysis identified the topological and density functional theory derived descriptors for antimicrobial models using a population of 200 models with one to three descriptors that were crossed for 10,000 generations. Two or three descriptor models provided validated predictive models for antifungal and antibiotic properties with R2 values be...
Antifungal compounds are of interest to reduce commodity spoilage and exposure to mycotoxins. In ... more Antifungal compounds are of interest to reduce commodity spoilage and exposure to mycotoxins. In this study, a series of quantitative structure-activity relationship (QSAR) equations based on topological properties were developed to gain insight into the antifungal activities of phenolic compounds. The molecules were geometry optimized using B3LYP/6-311+G** density functional theory calculations. Analysis of the frontier orbital properties revealed that conjugated phenolic compounds possessed smaller band gap energies. Genetic function approximation (GFA) on populations of 100 one to two descriptor models over 10,000 generations identified several models for antifungal activity against Fusarium verticillioides , Fusarium oxysporum , Aspergillus flavus , Aspergillus fumigatus , Penicillium expansum , and Penicillium brevicompactum. Phenolic compounds with greater antifungal activity possessed a lower electrophilicity index. The correlation coefficients for the one and two descriptor models ranged from 0.627 to 0.790 and 0.762 to 0.939, respectively. Molecular descriptors associated with electrostatic and topological properties are important to describe the antifungal activities of the phenolic compounds studied.
Hydroxytyrosol and tyrosol phospholipids were enzymatically synthesized and investigated for thei... more Hydroxytyrosol and tyrosol phospholipids were enzymatically synthesized and investigated for their bilayer properties. Dynamic light scattering demonstrated that hand extrusion at 100nm consistently resulted in liposomes of nearly 85nm diameter for both phosphatidyl-hydroxytyrosol (DOPHT) and phosphatidyl-tyrosol (DOPT). Transmission electron microscopy showed DOPT and DOPHT liposomes extruded at 100-nm to be spherical and non-distinctive from one another. Zeta potential measurements resulted in surface charges<-25mV, demonstrating both DOPT and DOPHT form highly stable liposomes. Quartz crystal microbalance with dissipation monitoring measurements demonstrated that liposomal adsorption was dependent on a combination of DOPT (or DOPHT) mole-percent and calcium ions concentration. Fluorescence anisotropy measurements indicated that melting temperatures of DOPT and DOPHT were below 4°C, suggesting that adsorption behavior and liposome formation was limited by electrostatic interact...
Aqueous cellulose gels were prepared by extraction of ground corn cobs with hot aqueous sodium hy... more Aqueous cellulose gels were prepared by extraction of ground corn cobs with hot aqueous sodium hydroxide/sodium hypochlorite and shearing. Initial shearing in a blender broke up cob tissue structure into individual cells and resulted in a gel. Subsequent shearing in a high pressure homogenizer increased viscosity by 50–100×. Rheological studies showed all samples were gel-like from 0.5 to 2.0% and
2-Aminopurine is a useful fluorescence probe for structure and interactions of single and double-... more 2-Aminopurine is a useful fluorescence probe for structure and interactions of single and double-stranded DNA, sensing changes in helical structure and exposure to water.(D. Xu, K.O. Evans and T.M. Nordlund (1994) Biochemistry 33,9592-9599.) 2D proton NMR and fluorescence spectral measurements of 2-aminopurine mononucleosides indicate the presence of two conformations in equilibrium in solution near room temperature. The NMR results showed
Feruloyl-sn-glycerol (FG) and 1,3-diferuloyl-sn-glycerol (F2G), the by-product of biocatalytic tr... more Feruloyl-sn-glycerol (FG) and 1,3-diferuloyl-sn-glycerol (F2G), the by-product of biocatalytic transesterification soybean oil and ethyl ferulate, were examined for their behavior in phospholipid vesicles. Based on absorbance and fluorescence methods, FG and F2G both were found to partition into vesicles and incorporate well into 1,2-dioleoylphosphocholine (DOPC) vesicles. FG and F2G incorporation resulted in vesicles that were as or slightly more stable than the unloaded vesicles. FG and F2G both demonstrated the ability to maintain antioxidant properties within the lipid bilayer. Bilayer depth analysis was conducted using the parallax method and molecular modeling.
A small cationic peptide (JH8944) was tested for activity against a number of pathogens of agricu... more A small cationic peptide (JH8944) was tested for activity against a number of pathogens of agricultural crops. JH8944 inhibited conidium growth in most of the tested plant pathogens with a dose of 50 μg/ml, although one isolate of Fusarium oxysporum was inhibited at 5 μg/ml of JH8944. Most conidia of Fusarium graminearum were killed within 6 hours of treatment with 50 μg/ml of JH8944. Germinating F. graminearum conidia required 238 μg/ml of JH8944 for 90% growth inhibition. The peptide did not cause any damage to tissues surrounding maize leaf punctures when tested at a higher concentration of 250 μg/ml even after 3 days. Liposomes consisting of phosphatidylglycerol were susceptible to leakage after treatment with 25 and 50 μg/ml of JH8944. These experiments suggest this peptide destroys fungal membrane integrity and could be utilized for control of crop fungal pathogens.
Time-Resolved Laser Spectroscopy in Biochemistry IV, 1994
Incorporation of 2-aminopurine (2AP) for adenine in DNA gives an optical probe of local and globa... more Incorporation of 2-aminopurine (2AP) for adenine in DNA gives an optical probe of local and global DNA conformation, since 2AP does not seriously disturb the B-DNA structure. The temperature dependence of the absorption of the double-stranded d[CTGA[2AP]TTCAG]2 DNA decamer shows that the helix melts in an all-or-none fashion. Absorbance at wavelengths of 260 nm and 330 nm monitor, respectively, the `average' normal base conformation and the 2AP base local conformation. The 2AP base locally melts at a temperature 0.5 degree(s)C or less below the other bases. Temperature dependence of the longest fluorescence decay time of the decamer also shows the melting transition, with the transition curve shifted a few degrees higher. Temperature dependent fluorescence spectral shifts, on the other hand, suggest the environment of the 2AP base changes about 10 degree(s)C below the primary melting temperature. The data suggest a premelting transition purely dynamic in nature--transient 2AP exposure to water increases but the average conformation remains B helical. A summary of conformational information extractable from 2AP fluorescence measurements is presented.
Time-Resolved Laser Spectroscopy in Biochemistry IV, 1994
Absorption and fluorescence spectra of the DNA duplex decamer d[CTGA(2AP)TTCAG]2 have been measur... more Absorption and fluorescence spectra of the DNA duplex decamer d[CTGA(2AP)TTCAG]2 have been measured as a function of temperature. Emission is dominated by the 2-aminopurine (2AP) base. A fluorescence excitation band near 260 to 270 nm disappears near the duplex melting temperature but reappears at higher temperatures, indicating singlet-singlet energy transfer occurs between normal DNA bases and the 2AP base in the B-helical conformation and to a lesser extent in the structurally-mobile melted conformation. The efficiency of transfer is 4 to 5% at 4 degree(s)C under the assumption of a single acceptor; preferential transfer to a low-fluorescence conformation of 2AP would imply no more than a two-times greater transfer efficiency. Emission spectra excited at 260 nm (energy transfer band), 330 nm (basepaired conformation of 2AP) and 305 nm (nonpaired 2AP conformation) appear to indicate transfer occurs from normal DNA bases to both 2AP conformers.
The phenols hydroxytyrosol and tyrosol made abundantly available through olive oil processing wer... more The phenols hydroxytyrosol and tyrosol made abundantly available through olive oil processing were enzymatically transesterified into effective lipophilic antioxidants with cuphea oil. The hydroxytyrosyl and tyrosyl esters made from cuphea oil were assessed for their ability to partition into, locate within and effect the bilayer behavior of 1,2-dioloeoylphosphatidylcholine liposomes and compared to their counterparts made from decanoic acid. Partitioning into liposomes was on the same scale for both hydroxytyrosyl derivatives and both tyrosyl derivatives. All were found to locate nearly at the same depth within the bilayer. Each was found to affect bilayer behavior in a distinct manner.
Journal of the American Oil Chemists' Society, 2012
The effect of desaturation from the C9 to the C15 carbon of 2‐monoacylglycerol (2‐MAG) fatty acid... more The effect of desaturation from the C9 to the C15 carbon of 2‐monoacylglycerol (2‐MAG) fatty acids on spontaneous acyl migration is described. Three 2‐MAG species, 2‐monooleoylglycerol (C18:1 cis‐Δ9), 2‐monolinoleoylglycerol (C18:2 cis‐Δ9,12), and 2‐monolinolenoylglycerol (C18:3 cis‐Δ9,12,15) were synthesized by lipase‐catalyzed ethanolysis of their respective triacylglycerols and isolated in >60 % yield and at 2‐MAG purities of >95 % relative to 1‐monoacylglycerol (1‐MAG). 1H‐NMR spectroscopy was used to monitor the spontaneous acyl migration of the 2‐MAG species over a temperature range from 20 to 80 °C. The relative energies of activation calculated from the Arrhenius relationships of the 2‐MAG acyl migration rate constants were 73.3, 68.0, and 72.9 kJ mol−1 for the three 2‐MAG species, respectively. Density functional calculations performed using the B3LYP functional at the 6‐31+G* basis set on the three ketal ring intermediate of the three 2‐MAG species followed a similar...
Mycotoxin sequestration materials are important tools to reduce mycotoxin illness and enable prop... more Mycotoxin sequestration materials are important tools to reduce mycotoxin illness and enable proper handling of mycotoxin-contaminated commodities. Three food-grade bentonite clays and four generally recognized as safe (GRAS) charcoal/biochar carbon materials that are marketed as feed additives and supplements were evaluated for their ability to sequester the mycotoxins aflatoxin B1, ochratoxin A, and zearalenone. The surface area of the clays varied between 32.1 to 51.4 mg2/g, and the surface area of the carbon-based materials varied from 1.7 to 1735 mg2/g. In vitro, gastric fluid studies indicated that certain pine biochar and activated coconut charcoal could sequester high amounts (85+%) of the mycotoxins at 1 ppm levels or below. However, some biochar materials with lower surface area properties lacked binding capacity. The coconut shell charcoal and pine biochar utilize agricultural waste products in a manner that significantly reduces carbon emissions and provides valuable mat...
Predictive models were developed using two-dimensional quantitative structure activity relationsh... more Predictive models were developed using two-dimensional quantitative structure activity relationship (QSAR) methods coupled with B3LYP/6-311+G** density functional theory modeling that describe the antimicrobial properties of twenty-four triazolothiadiazine compounds against Aspergillus niger, Aspergillus flavus and Penicillium sp., as well as the bacteria Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa. B3LYP/6-311+G** density functional theory calculations indicated the triazolothiadiazine derivatives possess only modest variation between the frontier orbital properties. Genetic function approximation (GFA) analysis identified the topological and density functional theory derived descriptors for antimicrobial models using a population of 200 models with one to three descriptors that were crossed for 10,000 generations. Two or three descriptor models provided validated predictive models for antifungal and antibiotic properties with R2 values be...
Antifungal compounds are of interest to reduce commodity spoilage and exposure to mycotoxins. In ... more Antifungal compounds are of interest to reduce commodity spoilage and exposure to mycotoxins. In this study, a series of quantitative structure-activity relationship (QSAR) equations based on topological properties were developed to gain insight into the antifungal activities of phenolic compounds. The molecules were geometry optimized using B3LYP/6-311+G** density functional theory calculations. Analysis of the frontier orbital properties revealed that conjugated phenolic compounds possessed smaller band gap energies. Genetic function approximation (GFA) on populations of 100 one to two descriptor models over 10,000 generations identified several models for antifungal activity against Fusarium verticillioides , Fusarium oxysporum , Aspergillus flavus , Aspergillus fumigatus , Penicillium expansum , and Penicillium brevicompactum. Phenolic compounds with greater antifungal activity possessed a lower electrophilicity index. The correlation coefficients for the one and two descriptor models ranged from 0.627 to 0.790 and 0.762 to 0.939, respectively. Molecular descriptors associated with electrostatic and topological properties are important to describe the antifungal activities of the phenolic compounds studied.
Hydroxytyrosol and tyrosol phospholipids were enzymatically synthesized and investigated for thei... more Hydroxytyrosol and tyrosol phospholipids were enzymatically synthesized and investigated for their bilayer properties. Dynamic light scattering demonstrated that hand extrusion at 100nm consistently resulted in liposomes of nearly 85nm diameter for both phosphatidyl-hydroxytyrosol (DOPHT) and phosphatidyl-tyrosol (DOPT). Transmission electron microscopy showed DOPT and DOPHT liposomes extruded at 100-nm to be spherical and non-distinctive from one another. Zeta potential measurements resulted in surface charges<-25mV, demonstrating both DOPT and DOPHT form highly stable liposomes. Quartz crystal microbalance with dissipation monitoring measurements demonstrated that liposomal adsorption was dependent on a combination of DOPT (or DOPHT) mole-percent and calcium ions concentration. Fluorescence anisotropy measurements indicated that melting temperatures of DOPT and DOPHT were below 4°C, suggesting that adsorption behavior and liposome formation was limited by electrostatic interact...
Aqueous cellulose gels were prepared by extraction of ground corn cobs with hot aqueous sodium hy... more Aqueous cellulose gels were prepared by extraction of ground corn cobs with hot aqueous sodium hydroxide/sodium hypochlorite and shearing. Initial shearing in a blender broke up cob tissue structure into individual cells and resulted in a gel. Subsequent shearing in a high pressure homogenizer increased viscosity by 50–100×. Rheological studies showed all samples were gel-like from 0.5 to 2.0% and
2-Aminopurine is a useful fluorescence probe for structure and interactions of single and double-... more 2-Aminopurine is a useful fluorescence probe for structure and interactions of single and double-stranded DNA, sensing changes in helical structure and exposure to water.(D. Xu, K.O. Evans and T.M. Nordlund (1994) Biochemistry 33,9592-9599.) 2D proton NMR and fluorescence spectral measurements of 2-aminopurine mononucleosides indicate the presence of two conformations in equilibrium in solution near room temperature. The NMR results showed
Feruloyl-sn-glycerol (FG) and 1,3-diferuloyl-sn-glycerol (F2G), the by-product of biocatalytic tr... more Feruloyl-sn-glycerol (FG) and 1,3-diferuloyl-sn-glycerol (F2G), the by-product of biocatalytic transesterification soybean oil and ethyl ferulate, were examined for their behavior in phospholipid vesicles. Based on absorbance and fluorescence methods, FG and F2G both were found to partition into vesicles and incorporate well into 1,2-dioleoylphosphocholine (DOPC) vesicles. FG and F2G incorporation resulted in vesicles that were as or slightly more stable than the unloaded vesicles. FG and F2G both demonstrated the ability to maintain antioxidant properties within the lipid bilayer. Bilayer depth analysis was conducted using the parallax method and molecular modeling.
A small cationic peptide (JH8944) was tested for activity against a number of pathogens of agricu... more A small cationic peptide (JH8944) was tested for activity against a number of pathogens of agricultural crops. JH8944 inhibited conidium growth in most of the tested plant pathogens with a dose of 50 μg/ml, although one isolate of Fusarium oxysporum was inhibited at 5 μg/ml of JH8944. Most conidia of Fusarium graminearum were killed within 6 hours of treatment with 50 μg/ml of JH8944. Germinating F. graminearum conidia required 238 μg/ml of JH8944 for 90% growth inhibition. The peptide did not cause any damage to tissues surrounding maize leaf punctures when tested at a higher concentration of 250 μg/ml even after 3 days. Liposomes consisting of phosphatidylglycerol were susceptible to leakage after treatment with 25 and 50 μg/ml of JH8944. These experiments suggest this peptide destroys fungal membrane integrity and could be utilized for control of crop fungal pathogens.
Time-Resolved Laser Spectroscopy in Biochemistry IV, 1994
Incorporation of 2-aminopurine (2AP) for adenine in DNA gives an optical probe of local and globa... more Incorporation of 2-aminopurine (2AP) for adenine in DNA gives an optical probe of local and global DNA conformation, since 2AP does not seriously disturb the B-DNA structure. The temperature dependence of the absorption of the double-stranded d[CTGA[2AP]TTCAG]2 DNA decamer shows that the helix melts in an all-or-none fashion. Absorbance at wavelengths of 260 nm and 330 nm monitor, respectively, the `average' normal base conformation and the 2AP base local conformation. The 2AP base locally melts at a temperature 0.5 degree(s)C or less below the other bases. Temperature dependence of the longest fluorescence decay time of the decamer also shows the melting transition, with the transition curve shifted a few degrees higher. Temperature dependent fluorescence spectral shifts, on the other hand, suggest the environment of the 2AP base changes about 10 degree(s)C below the primary melting temperature. The data suggest a premelting transition purely dynamic in nature--transient 2AP exposure to water increases but the average conformation remains B helical. A summary of conformational information extractable from 2AP fluorescence measurements is presented.
Time-Resolved Laser Spectroscopy in Biochemistry IV, 1994
Absorption and fluorescence spectra of the DNA duplex decamer d[CTGA(2AP)TTCAG]2 have been measur... more Absorption and fluorescence spectra of the DNA duplex decamer d[CTGA(2AP)TTCAG]2 have been measured as a function of temperature. Emission is dominated by the 2-aminopurine (2AP) base. A fluorescence excitation band near 260 to 270 nm disappears near the duplex melting temperature but reappears at higher temperatures, indicating singlet-singlet energy transfer occurs between normal DNA bases and the 2AP base in the B-helical conformation and to a lesser extent in the structurally-mobile melted conformation. The efficiency of transfer is 4 to 5% at 4 degree(s)C under the assumption of a single acceptor; preferential transfer to a low-fluorescence conformation of 2AP would imply no more than a two-times greater transfer efficiency. Emission spectra excited at 260 nm (energy transfer band), 330 nm (basepaired conformation of 2AP) and 305 nm (nonpaired 2AP conformation) appear to indicate transfer occurs from normal DNA bases to both 2AP conformers.
The phenols hydroxytyrosol and tyrosol made abundantly available through olive oil processing wer... more The phenols hydroxytyrosol and tyrosol made abundantly available through olive oil processing were enzymatically transesterified into effective lipophilic antioxidants with cuphea oil. The hydroxytyrosyl and tyrosyl esters made from cuphea oil were assessed for their ability to partition into, locate within and effect the bilayer behavior of 1,2-dioloeoylphosphatidylcholine liposomes and compared to their counterparts made from decanoic acid. Partitioning into liposomes was on the same scale for both hydroxytyrosyl derivatives and both tyrosyl derivatives. All were found to locate nearly at the same depth within the bilayer. Each was found to affect bilayer behavior in a distinct manner.
Journal of the American Oil Chemists' Society, 2012
The effect of desaturation from the C9 to the C15 carbon of 2‐monoacylglycerol (2‐MAG) fatty acid... more The effect of desaturation from the C9 to the C15 carbon of 2‐monoacylglycerol (2‐MAG) fatty acids on spontaneous acyl migration is described. Three 2‐MAG species, 2‐monooleoylglycerol (C18:1 cis‐Δ9), 2‐monolinoleoylglycerol (C18:2 cis‐Δ9,12), and 2‐monolinolenoylglycerol (C18:3 cis‐Δ9,12,15) were synthesized by lipase‐catalyzed ethanolysis of their respective triacylglycerols and isolated in >60 % yield and at 2‐MAG purities of >95 % relative to 1‐monoacylglycerol (1‐MAG). 1H‐NMR spectroscopy was used to monitor the spontaneous acyl migration of the 2‐MAG species over a temperature range from 20 to 80 °C. The relative energies of activation calculated from the Arrhenius relationships of the 2‐MAG acyl migration rate constants were 73.3, 68.0, and 72.9 kJ mol−1 for the three 2‐MAG species, respectively. Density functional calculations performed using the B3LYP functional at the 6‐31+G* basis set on the three ketal ring intermediate of the three 2‐MAG species followed a similar...
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