Concentrations Of Propyl Gallate Research Articles

Use of Propyl Gallate in Cardoon Biodiesel to Keep Its Main Properties during Oxidation

The use of alternatives for petroleum-based products is becoming more and more important, especially considering the new and constantly changing geopolitical context, where excessive energy dependence is not desirable. Thus, biodiesel could play an important role in contributing to the implementation of biorefineries, which represent desirable goals in terms of sustainability, green chemistry and the circular economy. However, one challenge related to biodiesel based on vegetable oils is its low oxidative stability, which can alter the properties of these products during storage. To avoid this problem, interesting antioxidants, such as propyl gallate (PG), could be added to biodiesel to allow it to keep its main properties during oxidation. Additionally, monitoring PG content during oxidation is interesting, and the use of voltammetry could be suitable for this purpose. The aim of this work was to assess the effectiveness of PG during cardoon biodiesel oxidation, while monitoring the process through cyclic voltammetry (CV). As a result, it was proven that PG was highly effective, increasing the length of oxidative stability to more than 10 h at low concentrations (600 mg·L−1) and retaining its main properties (viscosity and acidity) during oxidation. Regarding CV, this technique was successfully optimized to determine PG concentration in cardoon biodiesel during oxidation.

Propyl Gallate Treatment Improves the Postharvest Quality of Winter Jujube (Zizyphus jujuba Mill. cv. Dongzao) by Regulating Antioxidant Metabolism and Maintaining the Structure of Peel

The quality and color of winter jujube fruits are easy to change after harvest. We studied the regulation mechanism of propyl gallate (PG) on post-harvest physiological quality of winter jujube, from the perspective of antioxidant metabolism and peel structure. In our research, winter jujube fruits were treated with 0.001 mol L−1 PG solution for 20 min. Our results showed that PG delayed the development of peel color, and improved the firmness, total soluble solids (TSS), and titratable acid (TA) of winter jujube. Meanwhile, the PG treatment had higher content of total phenols, total flavonoids, ascorbic acid (AsA), and reduced glutathione (GSH), and kept the enzyme activity including superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and peroxidase (POD) at a higher level. PG treatment reduced membrane oxidative damage and maintained the integrity of pericarp structure by reducing electrolyte leakage (EL), lipoxygenase activity (LOX), hydrogen peroxide (H2O2), and malondialdehyde (MDA) content in the peel. Accordingly, PG improved the postharvest quality of jujube fruits by regulating antioxidant metabolism and maintaining the structure of peel. The appropriate concentration of PG has good application potential in the storage and preservation of fresh fruits such as winter jujube.

Dual-ratiometric electrochemical sensor for propyl gallate detection

A dual-ratiometric electrochemical sensor was constructed for propyl gallate (PG) detection based on anthraquinone/multi-walled carbon nanotube/chitosan modified glassy carbon electrode (AQ/MWCNT/CS/GCE). In the presence of the analyte PG, the AQ/MWCNT/CS/GCE displays three current peaks at different potentials, which are respectively related to the electro-oxidation of PG, AQ, and MWCNT. Anthraquinone and multi-walled carbon nanotube can be then used as inner reference electroactive probes. It was demonstrated that the modification of the GCE with AQ, MWCNT and chitosan can enhance the electrochemical signal of PG, leading to the improvement in the sensitivity of PG detection. Two ratiometric signals, namely, IPG/IAQ and IPG/IMWCNT, linearly increase with the increasing concentration of PG over the range of 1.0 to 30.0 μM, and the detection limit for PG detection are respectively estimated to be 0.67 μM and 0.76 μM. The electrochemical sensor can be applied for PG detection in edible oil samples with satisfactory results.

Effects of Temperature, Antioxidants, and High‐Vacuum Distillation on the Oxidation of Biodiesel Derived from Waste Vegetable Oil

AbstractBiodiesel offers several environmental benefits and improvements to some fuel performance properties, but its poor oxidative stability has been a major concern. Currently, the accepted practice to improve biodiesel oxidative stability is the addition of antioxidants; numerous antioxidants have been studied but their effectiveness in inhibiting biodiesel oxidation is difficult to predict due to variation with resonance stability, solubility, reactivity, and volatility. To improve prediction efforts, this study explored the Rapid Small‐Scale Oxidation Test (RSSOT) as a means to investigate how biodiesel oxidation is affected by antioxidant concentration and temperature, and compared its results with the oxidative stability index test. A weak correlation was identified due to antioxidant variation. A kinetic model expressed in temperature and induction period was developed for biodiesel before high‐vacuum distillation (HVD), after HVD and also after HVD with three concentrations of propyl gallate (PG) and tert‐butylhydroquinone (TBHQ) antioxidants. The approach was validated by comparing collected data on the oxidation of methyl oleate with kinetic parameters found in the literature. Antioxidant concentrations from 130–930 ppm were tested, and the results revealed that the apparent activation energy of biodiesel oxidation increases with increasing concentration of primary antioxidants and decreases during vacuum distillation. When treated with an increasing concentration (130–930 ppm) of PG and TBHQ, the apparent activation energies of a vacuum distilled biodiesel changed from 108.46 ± 4.45 to 112.72 ± 1.46 kJ·mol−1 and from 77.14 ± 2.25 to 89.91 ± 2.29 kJ·mol−1, respectively. These observed trends agree with both the accepted mechanism of primary oxidation of fuels and mode of action of primary antioxidants.

A Novel Approach to Fabricate Foam Ceramics from Steel Slag

A novel approach is used for fabricating steel slag foam ceramics based on the particle‐stabilized foaming method. In this work, steel slag was used as the raw material and propyl gallate (PG) was used as the surface modifier. For the first time, steel slag ceramic foams were successfully fabricated based on particle‐stabilized foams. The results show that the stability of the ceramic foams was closely related to the pH value and PG concentration. The porosity and compressive strength could be controlled by changing the solid loading of steel slag and sintering temperature. The porosity of steel slag foam ceramics ranged from 85.6% to 62.53%, and the compressive strength was from 1.74 MPa to 10.42 MPa. The thermal conductivity of steel slag foam ceramics was only 0.067 W (m·K)−1, which shows that it could be used as a thermal insulation material.

Highly porous barium strontium titanate (BST) ceramic foams with low dielectric constant from particle‐stabilized foams

AbstractA novel method for fabrication of highly porous barium strontium titanate (BST) ceramic foams based on particle‐stabilized foaming method was developed for the first time, in which propyl gallate (PG) was employed as BST particle modifier. The results showed that the stability of wet BST foams closely depends on the pH value and PG concentration, which could be explained by the adsorption behavior of PG on BST particle surface. BST ceramic foams with dense, uniform, and closed pore and defect‐free wall were obtained. The pore size and porosity can be well controlled by adjusting solid loading and sintering temperature. It was revealed that not only sintering temperature but also solid loading significantly influenced the growth of BST grain. The BST ceramic foams exhibited high porosity in the range of 81%‐95%, low dielectric constant in the range of 47‐150, and low dielectric loss below 0.0025. The BST ceramic foams with higher porosity presented a tendency of lower dielectric constant and the fitting results indicated that the natural logarithm of dielectric constant was linear correlated with porosity.

A novel fabrication method for glass foams with small pore size and controllable pore structure

AbstractIn this paper, a novel fabrication method for glass foams has been introduced based on colloidal suspension foaming method using waste glass as starting materials. It is demonstrated for the first time that foam stabilization via in‐situ hydrophobization of waste glass particles is possible. The fabrication conditions for stable glass particle‐stabilized foams are optimized by investigating the influences of pH value, concentration of propyl gallate and ball milling time, respectively. It is demonstrated that this is a versatile method for fabrication of stable foamed glass suspension and final glass foams with small pore size of dozens of microns, which is much smaller than that of most glass foams in previous literatures. This novel method enables both closed pore structure and open pore structure simply by tailoring solid loading of glass suspension. A “sieve‐like” hierarchical pore structure can be achieved by adjusting sintering temperature. The glass foams with controllable structure could be applied in thermal insulation fields for closed pores, and in catalyst loading, filtration, and separation fields for open pores and hierarchical pore structure.

Simultaneous Voltammetric Determination of tert-Butylhydroquinone and Propyl Gallate in Biodiesel–Ethanol at a Pt Ultramicroelectrode

A direct non-aqueous method for simultaneous determination of propyl gallate (PG) and tert-butylhydroquinone (TBHQ) in biodiesel (B100) is described. Differential pulse voltammetry (DPV) using a Pt disk ultramicroelectrode (ume) in 1:1 (v/v) B100/ethanol containing 0.02 mol L–1 tetrahexylammonium perchlorate showed two oxidation peaks in the range from 1.20 × 10–3 to 8.9 × 10–3 mol L–1 for TBHQ and from 8.6 × 10–4 to 4.9 × 10–3 mol L–1 for PG. Simultaneous quantification and addition–recovery experiments were carried out in antioxidant-free B100 samples spiked with variable concentrations of TBHQ and PG. Because of significant overlapping in oxidation signals, the amount of TBHQ and PG in B100 was calculated through calibration graphs after voltammogram deconvolution using Microcal Origin software (version 8.0). The method provides a direct, low-cost, non-aqueous, and small volume procedure for simultaneous quantification of TBHQ and PG in B100, with 116 and 104% recovery values, respectively.

Immunofluorescence evaluation of 4-hydroxynonenal and 8-hydroxy-2-deoxyguanosine activation in zebrafish (Daino rerio) larvae brain exposed (microinjected) to propyl gallate

Propyl gallate (PG) is a chemical compound obtained by esterification of propanol with gallic acid. Due to its antioxidative properties, it is widely used in cosmetics and pharmaceutical industries as well as to protect the oils in foods such as butter, milk-based desserts, chewing gum, mayonnaise, meat, soups, cereals, spices and seasonings from rancidity. This study has been designed to assessment 8-OHdG and 4-HNE activity, and histopathological changes in the brain tissues of zebrafish larvae, which is a lecithotrophic organism, after 96 h of PG exposure via microinjecting to yolk sac of embryo. To this end, approximately 5 nL of various concentrations of PG (1, 10, and 50 ppm) has been injected into yolk sac of fertilized embryo (final exposure concentrations are 5, 50, 250 pg/egg) with micro manipulator system. After 96 h exposure time, propyl gallate caused immunofluorescence positivity of 8-OHdG and 4-HNE in the brain tissues of zebrafish larvae. PG was not effect brain tissue histopathological in low concentrations (1 and 10 ppm) but highest concentration (50 ppm) caused degenerative changes in brain. These results suggests that PG treatment could lead oxidative DNA damage by causing an increase 8-OHdG and 4-HNE activities. This strategy will enable us to better understand the mechanisms of propyl gallate in brain tissues of zebrafish larvae.

Dielectric Strength Improvement of Natural Ester Insulation Oil via Mixed Antioxidants: Taguchi Approach

<span lang="EN-US">Recently, natural ester insulation (NEI) oils are found to be the best candidates to replace mineral-based insulation oils for oil-immersed transformer applications. However, NEI oils are prone to oxidation due to their poor oxidative stability which can be improved by adding antioxidants into the oils. Latest studies have also shown that the use of selected antioxidants improves the AC breakdown voltage (BdV) of NEI oils. However, the experiments in previous studies were designed using the conventional one-factor-at-a-time (OFAT) method, which requires a large number of samples to be tested in order to determine the optimum response. Thus, a Taguchi-based designed experiment is introduced in this study in replacement of the OFAT method. It is found that this method is capable of determining the optimum concentrations of propyl gallate (PG) and citric acid (CA) which will maximize the AC BdV and improve the oxidative stability of the NEI oil. An AC breakdown voltage test is conducted in accordance with the ASTM D1816 standard using Megger OTS60PB portable oil tester, in which the electrode gap distance is kept fixed at 1 mm. The results indicate that the addition of PG and CA antioxidants increases the AC BdV of the rapeseed-based NEI oil. It is found that the optimum concentrations of PG and CA antioxidant is 0.05 and 0.25 wt.%, respectively. Lastly, the model developed in this study is analysed using analysis of variance (ANOVA). Validation test is also conducted on the optimized NEI oil to determine its dielectric strength and oxidative stability.</span>

Determination of propyl gallate in edible oil by high-performance liquid chromatography with chemiluminescence detection

ABSTRACTA novel and convenient method based on high-performance liquid chromatography coupled with chemiluminescence (HPLC) for the determination of propyl gallate in edible oil is reported. The detection was based on the inhibition of chemiluminescence between luminol and hydrogen peroxide in alkaline solution. The analysis was performed using a C18 column with isocratic 60:40 methanol/water. Under the optimum conditions, the concentration of propyl gallate was linear from 9 × 10−6 mol L−1 to 1 × 10−4 mol L−1 with a detection limit of 2 × 10−7 mol L−1. The method is simple, sensitive, and inexpensive and was used for the determination of propyl gallate in edible oil.

Kinetic studies of bovine serum albumin interaction with PG and TBHQ using surface plasmon resonance

Propyl gallate (PG) and tert-butylhydroquinone (TBHQ) are examples of phenolic antioxidant agents, which have widespread uses in food industry. In this study, for the first time, we report on the interaction of PG and TBHQ with bovine serum albumin (BSA) using surface plasmon resonance (SPR). In order to modify Au slide with carboxyl functional group, 11-mercaptoundecanoic acid (MUA) was used. After activation of carboxylic groups, BSA was immobilized onto the MUA through both covalent amide bond and electrostatic binding formation. The SPR analysis showed dose-response sensograms of BSA upon increasing concentration of PG and TBHQ. At pH 4.5, the equilibrium dissociation constant or affinity unit (KD) for PG and TBHQ were 1.89e−10 and 1.49e−10 and at pH 7.5 were 4.74e−10 and 1.83e−9, respectively. The smaller amount of KD demonstrated high food additive molecules affinity to BSA. Based on these findings, it can be concluded that PG and TBHQ molecules can interact with BSA and effectively distributed within the body. Besides, SPR can be considered as useful automatic tool for quantification of PG and TBHQ interaction with serum albumin and it can deliver precise real-time kinetic data.

Electrochemical Sensor for Propyl Gallate, Based on Synergic Effect of Gold Nanoparticle and Poly(p-aminobenzenesulfonic Acid)

The present work reports the application of gold nanoparticle (AuNP)/poly(p-aminobenzenesulfonic acid) [poly(p-ABSA)] composite modified glassy carbon electrode (GCE) for the electrochemical determination of propyl gallate (PG). The AuNP/poly(p-ABSA) composite showed excellent electron transfer ability for the oxidation of PG by lowering the oxidation potential and remarkably enhancing the current response. Experimental parameters such as effect of pH, number of cycles of electro deposition, thickness of polymer film and scan rate were optimized. The calibration curve showed that the oxidation peak current was proportional to the concentration of PG in the range 1.0 × 10−4 to 9.0 × 10−6 M, with a correlation coefficient of 0.997 and limit of detection of 1.9 × 10−7 M. Diffusion coefficient of 2.3 × 10−6 cm2s−1 was calculated from chronoamperometric measurements. The designed sensor shows excellent reproducibility and stability. The developed sensor was successfully used to determine PG in edible vegetable oils and recoveries were between 98.9 and 101.3%.

In Vitro Formation of 8-hydroxy-2-deoxyguanosine (8-OHdG) in Calf Thymus DNA upon Treatment of 2-deoxyguanosine with Propyl Gallate and 2,6-di-tert-butyl-p-benzoquinone

Oxidative DNA damage caused by propyl gallate (PG) and 2,6-di- tert -butyl- p -benzoquinone (BHT-quinone, a metabolite of butylated hydroxytoluene (BHT)) was analyzed from the 8-hydroxy-2 ¢ -deoxyguanosine (8-OHdG) formation in calf thymus DNA and DNA base, 2 ¢ -deoxyguanosine (dG). PG in the presence of CuCl 2 increased the 8-OHdG formation in calf thymus DNA by around 9.17 times as compared to the control (untreated DNA). In the presence of CuCl 2 at 1.28×10 -5 M, the 8-OHdG per dG ratio resulting from the reaction of dG with PG at various concentrations (20–150 ppm) ranged from 75.50 to 312.06 8-OHdG per 10 5 dG. The 8-OHdG formation increased when the PG concentration was increased from 20 ppm to 80 ppm, and then, it began to plateau around 80 ppm. On the other hand, BHT-quinone increased the formation of 8-OHdG in the presence of CuCl 2 by 0.05 times as compared to the control (untreated DNA). LC-MS/MS analysis was used to identify the molecular structure of 8-OHdG, which had a base peak (M +. + 1) at m/z = 284 and two main fragments at m/z = 167.9 and m/z = 139.9.

Sensitized chemiluminescence of 2-phenyl-4,5-di(2-furyl)-1H-imidazole/K3Fe(CN)6/propyl gallate system combining with solid-phase extraction for the determination of propyl gallate in edible oil

In this paper, a novel chemiluminescence (CL) method has been developed for the determination of propyl gallate (PG). The proposed method was based on the enhancing effect of PG on the CL signal of 2-phenyl-4,5-di(2-furyl)-1H-imidazole (PDFI) and K3Fe(CN)6 reaction in an alkaline solution. Under the optimum conditions, the enhanced CL intensity was linearly related to the concentration of PG. The linear range of the calibration curve was 0.05–8μg/mL, and the corresponding detection limit (3σ) was 0.036μg/mL. The relative standard deviation for determining 1.0μg/mL PG was 2.8% (n=11). The proposed method has been successfully applied to the determination of PG in edible oil. The edible oil samples were prepared by the solid-phase extraction (SPE) with a C18 column served as the stationary phase. Furthermore, the possible CL mechanism was also discussed briefly based on the photoluminescence (PL) and CL spectra.

MWCNT-Modified Gold Electrode Sensor for the Determination of Propyl Gallate in Vegetable Oils

A differential pulse voltammetric method for the determination of the synthetic food antioxidant, propyl gallate (PG) was developed. Determination of PG was carried out using multiwalled carbon nanotube (MWCNT)-modified gold electrode (GE) in a solution of 0.1 M acetate buffer (pH 7) as supporting electrolyte. The developed sensor showed an excellent catalytic activity and stability for PG oxidation. Effect of common interfering ions, amount of MWCNT–Nafion suspension, pH of the supporting electrolyte, and scan rate were studied. Under optimized conditions, PG concentration as low as 6.3 × 10−7 M can be determined in food samples. The determination of PG in vegetable oils with the proposed sensor was in good agreement with those obtained by reported spectrophotometric method.

Research on Conditions of Solid-State Fermentation and Characters of Tannase by Aspergillus Niger B0201 with Gallnut

Study is on the solid-state fermentation of tannase with the Gallnut by Aspergillus niger B-0201.The experiments involved in the process and conditions of solid-state fermentation and factors influencing characters of tannase. The results indicated that the unpasteurized method before fermentation was in favor of the higher enzymic activity than the sterilized method. With the unpasteurized method, the tannase activity got the best level(51.2U/gds) ,when 5.0g of culture medium containing the 1g of Gallnut powder, 4g of the bran powder, 1% (w/w) of (NH4)2SO4, 0.1%(w/w) of NaCl, 0.1%(w/w) of MgSO4·7H2O, 8ml of water, 1.6:1 of the solid-to-liquid ratio and 1ml（1×108spores per milliliter）of inoculum size to a 250 ml conical flask was incubated at 30°C, initial pH6.0 for 96 hours. At the same time, the conditions of fermentation were further optimized using the Response Surface Design(RSM). The tannase activity got at 56.2U/gds with the .Gallnut(17%,w/w) and the solid-to-liquid ratio(1.5：1) in the medium under 32°C. The optimum temperature and pH of tannase was respectively 40°C and 5.0. Fe3+，Cu2+，Fe2+, Ba2+，Mn2+，Ca2+，Al3+were the inhibitor of tannase at 2.0mM concentration. The optimum concentration of propylgallate as the substrate catalyzed by Tannase was 1mM. The value of Kmwas 0.514mM and Vmaxwas 71.8μmol·(L·min)-1.

Effects of Propyl Gallate on adhesion of polymorphonuclear leukocytes to human endothelial cells induced by tumor necrosis factor alpha

To investigate the effects of Propyl Gallate (PrG) on cellular adhesion between human To investigate the effects of Propyl Gallate (PrG) on cellular adhesion between human umbilical vein endothelial cells (HUVEC) and polymorphonuclear leukocytes (PMN) as well as the expression umbilical vein endothelial cells (HUVEC) and polymorphonuclear leukocytes (PMN) as well as the expression of intercellular adhesion molecule-1 (ICAM-1, CD54) and E-selectin (CD62E) on the VEC surface. of intercellular adhesion molecule-1 (ICAM-1, CD54) and E-selectin (CD62E) on the VEC surface. A human VEC inflammation model was induced by tumor necrosis factor alpha (TNF-alpha). VECs were pre- A human VEC inflammation model was induced by tumor necrosis factor alpha (TNF-alpha). VECs were preincubated with varying concentrations of PrG (0.001-5 mmol/L) or 1 per thousand DMSO (v:v) or 10 mmol/L acetylsalicylic incubated with varying concentrations of PrG (0.001-5 mmol/L) or 1 per thousand DMSO (v:v) or 10 mmol/L acetylsalicylic acid (ASA) for 1 h, and then were stimulated with 10 ng/mL TNF-alpha for 6 h. Rose bengal vital staining method acid (ASA) for 1 h, and then were stimulated with 10 ng/mL TNF-alpha for 6 h. Rose bengal vital staining method was used to measure the adherence rate of PMN to VEC, while flow cytometry was used to determine the was used to measure the adherence rate of PMN to VEC, while flow cytometry was used to determine the expression of CD54 and CD62E on the VEC surface. expression of CD54 and CD62E on the VEC surface. After 6 h of incubation with TNF-alpha, the adherence After 6 h of incubation with TNF-alpha, the adherence of PMN to HUVECs as well as the percentage of fluorescence-positive cells and mean fluorescence intensity of PMN to HUVECs as well as the percentage of fluorescence-positive cells and mean fluorescence intensity (MFI) of surface CD54 and CD62E in HUVECs increased significantly ( (MFI) of surface CD54 and CD62E in HUVECs increased significantly (P<0.01). Pre-treatment of HUVECs with <0.01). Pre-treatment of HUVECs with PrG (0.1-5 mmol/L) significantly suppressed the adherence of PMN to VECs induced by TNF-alpha (PrG (0.1-5 mmol/L) significantly suppressed the adherence of PMN to VECs induced by TNF-alpha (P<0.05). PrG <0.05). PrG (1-5 mmol/L) inhibited the VEC surface expression of CD62E and CD54 in a dose-dependent way ( (1-5 mmol/L) inhibited the VEC surface expression of CD62E and CD54 in a dose-dependent way (P<0.05). PrG <0.05). PrG at lower concentrations (0.001-0.1 mmol/L) showed no effect on CD54 expression, while it showed a slightly at lower concentrations (0.001-0.1 mmol/L) showed no effect on CD54 expression, while it showed a slightly increasing trend in CD62E expression (increasing trend in CD62E expression (P>0.05). ASA at 10 mmol/L had no obvious effect on the positive rate of >0.05). ASA at 10 mmol/L had no obvious effect on the positive rate of CD62E and CD54. CD62E and CD54. High concentrations of PrG (0.1-5 mmol/L) exert its inhibitory effect on cellular High concentrations of PrG (0.1-5 mmol/L) exert its inhibitory effect on cellular adherence of PMN to HUVECs, and its mechanism may be related to inhibiting surface expression of CD54 and adherence of PMN to HUVECs, and its mechanism may be related to inhibiting surface expression of CD54 and CD62E in HUVECs. Its action concentration was lower than that of ASA. CD62E in HUVECs. Its action concentration was lower than that of ASA.

Impact of Phenolic Antioxidants on Structural Properties of Micellar Solutions

Antioxidants solubilized in micellar solutions can change micellar properties like the size and shape of micelles, critical micellar concentration (cmc) and viscosity. Interactions arising between antioxidants and the surfactant determine the locations of antioxidants and vice versa. The location and interaction are dependent on the type of both the antioxidant and surfactant. Influences of various antioxidants on the physical and structural properties were tested in micellar systems of cationic CTAB, non-ionic Brij 58 and anionic SDS. The antioxidants used to investigate the effects of gradually increasing lipophilicity were gallic acid (GA) and the gallate esters from methyl to octyl gallate (MG-OG). Hydroxy cinnamic acids (HCAs) like \(p\)-coumaric acid (pC), caffeic acid (CA), ferulic acid (FA) and sinapic acid (SA) were employed to observe effects of functional groups like hydroxyl and methoxy groups. Micellar size and shape determined by small angle neutron scattering (SANS), viscosity and cmc were chosen to characterize the antioxidant influence. In Brij 58 systems propyl gallate (PG) did not affect the cmc or aggregation number but decreased micellar size slightly due to an intercalation of PG into the region of the polyoxyethylene chain and the first adjacent alkyl chain methylene groups. In SDS systems the micellar size and cmc decreased in the presence of PG. This was attributed to PG residing in the Stern layer. However, in CTAB systems micelles swelled at low PG concentration and in the presence of GA, while higher PG concentrations and more lipophilic antioxidants led to a sphere-to-rod transition with a simultaneous increase in viscosity and decrease in cmc. This revealed the intercalation of antioxidants in the palisade layer of CTAB micelles entering into strong interactions of electrostatic and hydrophobic origin. It could be demonstrated that the interactions became stronger the more lipophil an antioxidant is and the more hydroxyl groups are attached to the aromatic ring. Differences in the location and interaction of antioxidant and micelles are proposed as being responsible for the effectiveness of antioxidants.

Effects of propyl gallate on interaction between TNF-alpha and sTNFR-I using an affinity biosensor1

To study the effects of propyl gallate on the interaction of tumor necrosis factor-alpha (TNF-alpha) with its soluble receptor, sTNFR-I. Interactions between TNF-alpha and sTNFR-I were analyzed using an IAsys biosensor. sTNFR-I was immobilized on the carboxymethyl dextran (CMD) surface of the IAsys biosensor cuvettes, and TNF-alpha preincubated with different concentrations of propyl gallate was added to the cuvettes. The resonant angle shift caused by the binding between TNF-alpha and sTNFR-I was then recorded. sTNFR-I was immobilized on the CMD surface at a density of 2.76 ng/mm(2). TNF-alpha then bound the immobilized sTNFR-I specifically, and propyl gallate was able to enhance the binding between TNF-alpha and sTNFR-I in a dose-dependent manner. The binding between TNF-alpha and sTNFR-I is one of the targets that propyl gallate can act on in vivo. The IAsys biosensor offers a new clue as to the study on the mechanisms of action of propyl gallate.