Taxiphyllin 6'-O-gallate, actinidioionoside 6'-O-gallate and myricetrin 2″-O-sulfate from the leaves of Syzygium samarangense and their biological activities.

Three new compounds were isolated from a MeOH extract of the leaves of Syzygium samarangense, one new cyanogenic glucoside, taxiphyllin 6'-O-gallate (1), one new megastigmane glucoside, actinidioionoside 6'-O-gallate (2), and one new sulfated flavonoid rhamnoside, myricetrin 2″-O-sulfate (3), together with 14 known compounds, lupeol (4), demethoxymatteucinol (5), cryptostrobin (6), betulinic acid (7), ß-sitosterol glucoside (8), 2R-prunasin (9), myrciaphenone A (10), 1-feruloyl-ß-D-glucopyranoside (11), (3S,5R,6R,7E,9S)-3,5,6,9-tetrahydroxymegastigman-7-ene (12), guaijaverin (13), myricetin 4'-methyl ether 3-O-α-L-rhamnopyranoside (14), myricetrin (15), gallic acid (16) and actinidioionoside (17). The structures of the new compounds were determined through a combination of spectroscopic, HPLC and chemical analyses.

Adsorption of gallic acid, propyl gallate and polyphenols from Bryophyllum extracts on activated carbon.

The adsorption of gallic acid (GA) and propyl gallate (PG) on activated carbon (AC) was studied as a function of the AC mass and temperature. Clean first order behavior was obtained for at least three half-lives and the equilibrium was reached after ∼4 h contact time. An increase in the temperature (T = 20-40 °C) increases their adsorption rate constant values (k1) by 2.5 fold but has a negligible effect on the amount of antioxidant adsorbed per mass of AC at equilibrium. We also analyzed the adsorption process of polyphenols from Bryophyllum extracts and ca 100% of the total amount of the polyphenols in the extract were adsorbed when using 7 mg of AC. Results can be explained on the basis of the Freundlich isotherm but do not fit the Langmuir model. Results suggest that the combination of emerging in vitro plant culture technologies with adsorption on activated carbon can be successfully employed to remove important amounts of bioactive compounds from plant extracts by employing effective, sustainable and environmental friendly procedures.

Determination of antioxidants in cosmetics by micellar electrokinetic capillary chromatography with electrochemical detection.

A new and efficient method for the determination of antioxidants [Propyl gallate (PG), tert-butylhydroquinone (TBHQ), butylated hydroxyanisole (BHA), and butylated hydroxytoluene (BHT)] in cosmetics has been established by using micellar electrokinetic capillary chromatography with electrochemical detection (MECC-ED). Under the optimum conditions of the method, all analytes were successfully separated within 13 min at the separation voltage of 18 kV in a 20 mmol/L borate running buffer (pH 7.4) containing 25 mmol/L sodium dodecyl sulfate. The excellent linearity was obtained in the concentration range from 5.0 x 10(-4) to 2.0 x 10(-6) mol/L and the detection limits (S/N = 3) of PG, TBHQ, BHA, and BHT range from 3 x 10(-7) to 3 x 10(-6) mol/L.

Molecularly imprinted electrochemical sensor for propyl gallate based on PtAu bimetallic nanoparticles modified graphene-carbon nanotube composites.

A novel molecularly imprinted electrochemical sensor for propyl gallate (PG) determination was developed via electropolymerization of an o-phenylenediamine membrane in the presence of template molecules on glassy carbon electrode surface modified by PtAu bimetallic nanoparticles-capped graphene-carbon nanotubes composites (PtAu-GrCNTs). The modified electrodes were characterized by cyclic voltammetry, scanning electron microscope, x-ray diffraction and chronoamperometry. Moreover, experimental parameters such as scan cycles, incubation time, molar ratios of template molecules to functional monomers and extraction time were optimized. It was found that the PtAu-GrCNTs composite could effectively enhance the electron transfer efficiency and remarkably improve the sensitivity of the sensor. The results revealed the sensor displayed superb resistance to no-specific binding, very attractive detection limit as low as 2.51×10(-8) mol/L, and a wide linear range from 7×10(-8) mol/L to 1×10(-5) mol/L towards PG. Furthermore, the MIPs sensor was also successfully used for the detection of PG in food samples. Therefore, the MIPs-based electrochemical sensing strategy might provide a sensitive, rapid, and cost-effective method for PG determination and related food safety analysis.

Ionic liquid-based aqueous biphasic systems as a versatile tool for the recovery of antioxidant compounds.

The comparative evaluation of distinct types of ionic liquid-based aqueous biphasic systems (IL-ABS) and more conventional polymer/salt-based ABS to the extraction of two antioxidants, eugenol and propyl gallate, is focused. In a first approach, IL-ABS composed of ILs and potassium citrate (C6H5K3O7/C6H8O7) buffer at pH 7 were applied to the extraction of two antioxidants, enabling the assessment of the impact of IL cation core on the extraction. The second approach uses ABS composed of polyethylene glycol (PEG) and potassium phosphate (K2HPO4/KH2PO4) buffer at pH 7 with imidazolium-based ILs as adjuvants. Their application to the extraction of the compounds allowed the investigation of the impact of the presence/absence of IL, the PEG molecular weight, and the alkyl side chain length of the imidazolium cation on the partition. It is possible to maximize the extractive performance of both antioxidants up to 100% using both types of IL-ABS. The IL enhances the performance of ABS technology. The data puts in evidence the pivotal role of the appropriate selection of the ABS components and design to develop a successful extractive process, from both environmental and performance points of view.

Ability of surfactant micelles to alter the partitioning of phenolic antioxidants in oil-in-water emulsions.

In oil-in-water emulsions, the physical location of antioxidants can be an important determinant in their activity. Surfactants can potentially influence the physical location of antioxidants in oil-in-water emulsions by causing solubilization of lipid-soluble antioxidants into the aqueous phase. Excess Brij micelles in an oil-in-water emulsion were found to increase the partitioning of phenolics into the continuous phase with polar antioxidants (propyl gallate) partitioning more than nonpolar antioxidants (butylated hydroxyltoluene). Solubilization of propyl gallate was rapid coming to equilibrium in less than 5 min. Increasing surfactant micelle concentrations from 0.3 to 2.8% increased the solubilization of propyl gallate by 2.3-fold. Solubilization of phenolic antioxidants into the aqueous phase by Brij micelles did not alter the oxidative stability of salmon oil-in-water emulsions, suggesting that surfactant micelles influenced oxidation rates by mechanisms other than antioxidant solubilization.

[Study on interaction of Radix Paeoniae 801 and endothelin-1 by using a piezoelectric quartz crystal biosensor].

OBJECTIVE: To explore the possible target and molecular mechanism of Radix Paeoniae 801 (RP801), an effective ingredient extracted from Radix Paeoniae, the Chinese herbal medicine for activating blood circulation to remove blood stasis, using experimental in vitro method by directly detecting the interaction between RP801 and endothelin-1 (ET-1). METHODS: Piezoelectric quartz crystal biosensor, namely, the quartz crystal microbalance (QCM) was used to detect the specific combining between RP801 and ET-1 by binding avidin to the pre-activated Au surface of electrode of QCM, followed by immobilizing biotinylated ET-1 to it, and adding RP801, then the binding curve was recorded. PBS washing was applied at the end of every steps of combining reaction for dissociate the non-specific absorption. RESULTS: Specific combining of RP801 and ET-1 was found. CONCLUSION: ET-1 could possibly be one of the acting targets of RP801 in the body, that is, RP801 could combine with ET-1 to impede the binding of ET-1 with its receptor, so as to counteract the action of ET-1, dilate blood vessels and inhibit platelet aggregation.

Cloud-point extraction and reversed-phase high-performance liquid chromatography for the determination of synthetic phenolic antioxidants in edible oils.

A cloud-point extraction (CPE) method using Triton X-114 (TX-114) nonionic surfactant was developed for the extraction and preconcentration of propyl gallate (PG), tertiary butyl hydroquinone (TBHQ), butylated hydroxyanisole (BHA), and butylated hydroxytoluene (BHT) from edible oils. The optimum conditions of CPE were 2.5% (v/v) TX-114, 0.5% (w/v) NaCl and 40 min equilibration time at 50 °C. The surfactant-rich phase was then analyzed by reversed-phase high-performance liquid chromatography with ultraviolet detection at 280 nm, using a gradient mobile phase consisting of methanol and 1.5% (v/v) acetic acid. Under the studied conditions, 4 synthetic phenolic antioxidants (SPAs) were successfully separated within 24 min. The limits of detection (LOD) were 1.9 ng mL(-1) for PG, 11 ng mL(-1) for TBHQ, 2.3 ng mL(-1) for BHA, and 5.9 ng mL(-1) for BHT. Recoveries of the SPAs spiked into edible oil were in the range 81% to 88%. The CPE method was shown to be potentially useful for the preconcentration of the target analytes, with a preconcentration factor of 14. Moreover, the method is simple, has high sensitivity, consumes much less solvent than traditional methods, and is environment-friendly. Practical Application: The method established in this article uses less organic solvent to extract SPAs from edible oils; it is simple, highly sensitive and results in no pollution to the environment.