Search results for "Hydroxybenzoates"
showing 5 items of 25 documents
Simultaneous determination of main phenolic acids and flavonoids in tomato by micellar electrokinetic capillary electrophoresis
2017
[EN] A methodology for the determination of tomato phenolic acids and flavonoids has been developed combining MEKC and DAD detection. The influence on polyphenol separation of pH and background electrolyte, BGE (borax, acetonitrile, methanol and SDS concentrations), was studied and optimized using response surface methodology and weighted desirability function. Separation of polyphenols was achieved within 20 min at 15 degrees C using 11.3 mM borax and 11.2 mM SDS adjusted to pH 8.5 as BGE. Validation was performed using standards and tomato extracts. Recoveries ranged from 77 to 106%. Acceptable repeatabilities were obtained for peak area (% RSD <3.1% and <3.7%) and migration times (% RSD …
Fixed oil from seeds of narrow-leaved ash (F. angustifolia subsp. angustifolia): Chemical profile, antioxidant and antiproliferative activities.
2019
Fraxinus angustifolia subsp. angustifolia is a plant with an age-old use for the production of manna. However, it is also a valuable source of fixed oil rich-seeds. In the present study we examined the chemical and biological properties of this oil in order to support a possible application in foodstuffs, nutraceuticals and cosmetics. Fatty acid composition, volatile and phenolic substances were evaluated. Oleic and linoleic acid represented 45.5% and 50.0%, respectively, of the total fatty acid composition. Among polar phenolic substances identified (secoiridoids, phenylethanoid glycosides, phenolic acids and alcohols, flavonoids, coumarins) isoverbascoside is for the first time reported i…
Synthesis and characterization of triphenyltin(IV) 5-[(E)-2-(aryl)-1-diazenyl]-2-hydroxybenzoates. Crystal and molecular structures of Ph3Sn{O2CC6H3-…
2005
Abstract Triphenyltin 5-[(E)-2-(4-methylphenyl)-1-diazenyl]-2-hydroxybenzoate, Ph3SnL2H, has been prepared and characterized, its structure determined by X-ray crystallography, and the structure compared with those of its homologues. Two polymorphs were isolated from the same crystallization attempt. The reactivity of tetrahedral Ph3SnL1H (L1H = 5-[(E)-2-(2-methylphenyl)-1-diazenyl]-2-hydroxybenzoate) towards 2,2′-bipyridine (bipy) has been investigated to ascertain the ability of bipy to coordinate to the Sn-complex and the resultant changes in the molecular architecture. The crystal structure of the product revealed that the bipy moiety does not coordinate to the Sn atom, but forms a cycl…
Inactivation of PadR, the repressor of the phenolic acid stress response, by molecular interaction with Usp1, a universal stress protein from Lactoba…
2009
ABSTRACT The phenolic acid decarboxylase gene padA is involved in the phenolic acid stress response (PASR) in gram-positive bacteria. In Lactobacillus plantarum , the padR gene encodes the negative transcriptional regulator of padA and is cotranscribed with a downstream gene, usp1 , which encodes a putative universal stress protein (USP), Usp1, of unknown function. The usp1 gene is overexpressed during the PASR. However, the role and the mechanism of action of the USPs are unknown in gram-positive bacteria. Therefore, to gain insights into the role of USPs in the PASR; (i) a usp1 deletion mutant was constructed; (ii) the two genes padR and usp1 were coexpressed with padA under its own promo…
Direct Visualization of Molecule Deprotonation on an Insulating Surface
2012
Elucidating molecular-scale details of basic reaction steps on surfaces is decisive for a fundamental understanding of molecular reactivity within many fields, including catalysis and on-surface synthesis. Here, the deprotonation of 2,5-dihydroxybenzoic acid (DHBA) deposited onto calcite (101;4) held at room temperature is followed in situ by noncontact atomic force microscopy. After deposition, the molecules form two coexisting phases, a transient striped phase and a stable dense phase. A detailed analysis of high-resolution noncontact atomic force microscopy images indicates the transient striped phase being a bulk-like phase, which requires hydrogen bonds between the carboxylic acid moie…