Search results for " Phenols"

Glass-capillary gas chromatography of chlorobenzenes on SE-30 and Carbowax 20M columns. Simultaneous determination of chlorobenzenes and chlorophenols

1983

Gas chromatography of benzene and all chlorobenzenes has been studied on SE-30 and Carbowax 20M glasscapillary columns under various operating conditions. The benzene isomers are eluted on both columns according to their boiling points. Separation of all components in a mixture is achieved on Carbowax 20M, whereas on SE-30 the peaks of closely related isomers overlapped. Also one partial overlapping is observed on a non-polar phase. The relative retention times for compounds are given and the retention order is discussed. The retention behaviour of chlorobenzenes and chlorophenols is compared. By using an SE-30 quartz-capillary column a mixture of 33 individual components gives 29 resolved …

Gas chromatographic separation of acetylated chlorinated phenols, guaiacols and catechols on an SE-30 quartz capillary column

1983

Natural polyphenols in cancer therapy.

2011

Natural polyphenols are secondary metabolites of plants involved in defense against different types of stress. Extracts containing these compounds have been used for thousands of years in traditional eastern medicine. Polyphenols act on multiple targets in pathways and mechanisms related to carcinogenesis, tumor cell proliferation and death, inflammation, metastatic spread, angiogenesis, or drug and radiation resistance. Nevertheless, reported effects claimed for polyphenols are controversial, since correlations between in vitro effects and in vivo evidence are poorly established. The main discrepancy between health claims versus clinical observations is the frequent use of nonphysiological…

Neutron Electron Spin Resonance dosimetry with phenol compounds

2014

Phenol compounds for Electron Spin Resonance (ESR) dosimetry in gamma and neutron field

2015

The use of neutrons for cancer treatments has stimulated the research for beam characterization in order to optimize the therapy procedures in Neutron Capture Therapy (Altieri, 2008). Several research laboratories have shown an increasing interest aimed at extending the applicability of Electron Spin Resonance (ESR) dosimetry to radiotherapy with different types of radiation beams. In particular, ESR spectrometry provides absorbed dose measurements through the detection of the stable free radicals produced by ionizing radiations. The ESR dosimetric method has many advantages such as simple and rapid dose evaluation, the readout procedure is non-destructive, linear response of many organic a…

Phytochemical study of Cistus libanotis L.

2015

n continuation of our ongoing study on Mediterranean Flora, we focused the attention on Cistus genus. These plants possess interesting secondary metabolites and are used in many fields, principally in perfumery and more recently as raw material for food supplements (botanicals). n this article, we report the phytochemical analysis of Cistus libanotis L. from Tunisia. Among the diterpenes, labdane compounds resulted absent, in favour of two clerodanes, one of that never reported in Cistus sp. The main representative compounds were found to be several flavonoids with various grades of O-methylation. Other interesting components were two cinnamic esters of borneol, reported here for the first …

Sensory-active compounds influencing wine experts' and consumers' perception of red wine intrinsic quality

2015

© 2014 Elsevier Ltd. There is a lack of studies focusing on the chemical compounds involved in quality perception. The present work combines both sensory and chemical approaches with the final goal of evaluating the sensory-active compounds influencing wine experts' and consumers' perception of red wine quality. Perceived quality was categorised by 108 consumers and 119 experts according to four levels going from very low to very high quality. In parallel, samples were described by a descriptive trained panel and volatile and non-volatile chemicals with known sensory activity were quantified. Wines with higher concentrations of eugenol, E- and Z-whiskylactones and 4-ethylphenol (discussed i…

Organocatalytic Enantioselective Synthesis of α-Hydroxyketones through a Friedel−Crafts Reaction of Naphthols and Activated Phenols with Aryl- and Al…

2016

[EN] An efficient organocatalytic asymmetric synthesis of alpha-hydroxyketones has been developed. Quinine-derived thiourea catalyzed the enantioselective Friedel Crafts alkylation of naphthols and activated phenols with aryl- and alkylglyoxal hydrates, providing the corresponding chiral alpha-hydroxyketones with high yields (up to 97%) and excellent enantioselectivities (up to 99% ee).

Influence of the drying processes of yeasts on their volatile phenol sorption capacity in model wine.

2009

International audience; Volatile phenols, such as 4-ethylphenol, are responsible for a "horsey" smell in wine. Thus, the study of volatile phenol sorption in yeasts, and their subsequent elimination from wine, helps to optimize eco-friendly wine curative processes. Here, we compared the influences of spray drying, lyophilization and evaporative drying at low water activity on yeast, for improving the 4-ethylphenol sorption capacity in a synthetic model wine. The changes that occur in the physico-chemical characteristics of the yeast surface (surface hydrophobicity, electron-donor character and zeta potential) during these drying processes were determined to assess if any correlation exists …

Tapentadol at medium to high doses in patients previously receiving strong opioids for the management of cancer pain.

2014

Abstract Abstract Objective: The aim of this study was to assess the efficacy and tolerability of tapentadol (TP) for a period of 4 weeks in patients who were already treated by opioids. Methods: A convenience sample of 30 patients was selected for a prospective observational cohort study. Cancer patients who were receiving at least 60 mg of oral morphine equivalents were selected. Patients discontinued their previous opioid analgesics before starting TP, in doses calculated according the previous opioid consumption (1:3.3 ratio with oral morphine equivalents). The subsequent doses were changed according to the patients' needs for a period of 4 weeks. Oral morphine was offered as a breakthr…