Matrix-free laser desorption ionization mass spectrometry as a functional tool for the analysis and differentiation of complex phenolic mixtures in propolis: a new approach to quality control.

Matrix-free laser desorption ionization (LDI) is a rapid and versatile technique for the ionization of small, UV-light-absorbing molecules. Indeed, many natural products such as polyphenols exhibit inherent LDI properties, potentially facilitating their detection from highly complex samples such as crude extracts. With this in mind, the present work thoroughly evaluated the potential of LDI as an analytical tool for the chemical profiling and differentiation of propolis samples obtained from different global regions. Propolis is a complex bee product containing, among others, significant amounts of phenolic constituents that may show LDI effects. The present work will demonstrate that LDI not only provides reproducible and highly specific fingerprint spectra for each of the tested samples, it further allows their clear differentiation by principal compound analysis (PCA). Contrary to classical analytical approaches such as LC- or GC-MS, LDI does not require time-consuming sample preparation and method optimization procedures. Thus, the technique represents a most interesting analytical tool and potent supplement to classic LC-MS for quality control of herbal pharmaceuticals and dietary supplements. Present results clearly support this approach and further suggest the use of LDI as a versatile tool for the automated analysis of large sample batches on an industrial scale. Graphical abstract ᅟ.

Chemical Composition of Laurencia obtusa Extract and Isolation of a New C15-Acetogenin.

A new C15-acetogenin, sagonenyne (20), exhibiting an unusual single tetrahydropyran ring was isolated from an ethyl acetate extract of Laurencia obtusa collected on the Corsican coastline. Its structure was established by detailed NMR spectroscopic analysis, mass spectrometry, and comparison with literature data. Twenty-three known compounds were identified in the same extract by means of column chromatography steps, using a 13C-NMR computer aided method developed in our laboratory. In addition to sesquiterpenes, which represent the main chemical class of this extract, diterpenes, sterols, and C15-acetogenins were identified. The crude extract was submitted to a cytotoxicity assay and was particularly active against THP-1 cells, a human leukemia monocytic cell line.

Potential of extracts from Saponaria officinalis and Calendula officinalis to modulate in vitro rumen fermentation with respect to their content in saponins.

Saponins have the potential to favorably modulate rumen fermentation, but there is generally a lack of the chemical structures associated with the described effects. The activity of extracts from Calendula officinalis and Saponaria officinalis in the rumen was evaluated in vitro. The S. officinalis root extract, reduced CH4 production by 8.5% and increased total VFA concentration by 25.2%. C. officinalis and S. officinalis root extracts and the S. officinalis aerial part extract decreased the acetate to propionate ratio from 8.6 to 17.4%, according to the extract. An HPLC-ELSD analysis indicated that the saponin content ranged from 43.6 to 57.6 mg/g of dry matter (DM) in the C. officinalis extracts and from 224.0 to 693.8 mg/g of DM in the S. officinalis extracts, expressed as the hederacoside C equivalent. Identification of the saponin compounds present in the extracts by HPLC-MS(n) suggested that the saponin profile modulated the biological activities, showing the importance of determining the structure of saponins when evaluating extracts.

Comparison of two methods, UHPLC-UV and UHPLC-MS/MS, for the quantification of polyphenols in cider apple juices.

The aim of this study was to develop faster and more efficient phenotyping methods for in-depth genetic studies on cider apple progeny. The UHPLC chromatographic system was chosen to separate polyphenolic compounds, and quantifications were then simultaneously performed with a UV-PDA detector and an ESI-triple quadrupole mass analyzer (SRM mode). Both quantification methods were validated for 15 major compounds using two apple juice samples, on the basis of linearity, limits of detection and quantification, recovery and precision tests. The comparison between UV and SRM quantifications in 120 different samples of a cider apple progeny showed an excellent correlation for major compounds quantified with both methods. However, an overestimation was revealed for five compounds with the UV detector and the mass analyzer. Co-elution and matrix effects are discussed to explain this phenomenon. SRM methods should therefore be considered with restrictions in some cases for quantification measurements when several phenolic compounds are simultaneously quantified in complex matrices such as apple juices. For both methods, analyses were carried out over short periods of time while maintaining a high quality for the simultaneous quantification of phenolic compounds in apple juice. Each method is relevant for more in-depth genetic studies of the polyphenol content of apple juice.

Influence of complexation phenomena with multivalent cations on the analysis of glyphosate and aminomethyl phosphonic acid in water.

Experimental and theoretical influence of multivalent cations on the analysis of glyphosate and aminomethyl phosphonic acid (AMPA) was studied in pure water and in one surface water. The procedure chosen, based on derivatization with FMOC-Cl, HPLC separation, and fluorescence detection, appears highly affected at cations concentrations current in natural waters. A detailed speciation study performed with the VMINTEQ software strongly suggests that the complexes formed between analytes and cations do not dissociate during the reaction and do not react with the derivatization agent, so that only the free forms are derivatized. These results point out the necessity of a pre-treatment to prevent these interferences, even in low salinity waters. The different ways conceivable are discussed in terms of kinetic and thermodynamic considerations.

Impact of UV-irradiation on the formation of odorous chloroaldimines in drinking water.

In order to explain some of the possible origins of an odor episode which took place in a drinking water supply in the region of Paris (France), the impact of disinfection on the formation of odorous by-products was investigated. We have previously established that very odorous and stable chloroaldimines are formed during amino acid chlorination in conditions relevant to those of drinking water treatment. As chlorination is preceded by a UV-irradiation step, we examined here the impact of this irradiation on the formation of chloroaldimines. Irradiation (30 m W cm(-2)) of various amino acids (glycine, valine, phenylalanine) and peptides (Phe-Gly-Gly-Phe, Phe-Ala) led to a degradation of the compounds but it was negligible at the doses applied in drinking water supplies. As peptides were concerned, contrary to what we previously expected, the degradation did not involve the peptidic bond breaking: irradiation induces therefore no increase in the quantity of free amino acids, precursors of odorous chloroaldimines. However chlorination of peptides (Phe-Ala-Ala-Val, Phe-Gly-Gly-Phe and Ala-Phe) showed that chloroaldimines are also probably formed during combined amino acids chlorination.

Effect of chlorination on the formation of odorous disinfection by-products.

In order to explain some of the possible origins of an odor episode, which took place in a drinking water supply in the region of Paris (France), the chlorination reaction of some simple amino acids (valine, leucine and phenylalanine) was investigated. In addition to the commonly admitted intermediates and products of this reaction (monochloramines, aldehydes and nitriles), the formation of far less documented products was observed: N-chloroaldimines which proved to present particular properties. These products appeared to remain relatively stable in water, especially at low temperatures, and can be formed under disinfection conditions relevant to those of drinking water treatment (i.e. at high chlorination rates). N-chloroaldimines also present strong swimming pool odors with a floral background, with odor detection thresholds close to 1microgL(-1) and even less. These values were established with a laboratory-made protocol. These products appeared more odorous than the corresponding aldehydes, known for a long time as potent odor causing chemicals and which have previously been involved in some odor problems in the field of drinking water treatment. N-chloroaldimines are consequently products of interest for water treaters and are now suspected to be a source of off-flavor concerns among consumers. We have therefore developed an analytical method (gas chromatography coupled with mass spectrometry) to demonstrate the presence of some of these compounds in water at concentrations close to their odor detection thresholds. Considering the levels of amino acids that can be reached in water, this level of chloroaldimines concentration could be obtained under certain pollution conditions.

Odorous products of the chlorination of phenylalanine in water: formation, evolution, and quantification.

To explain some of the possible origins of an odor episode which took place in a drinking water supply in the region of Paris (France), the chlorination reaction in water of phenylalanine was studied. This amino acid was chosen for first experiments because of its physical and chemical particular properties. Changes in the different byproducts formed were followed by high-performance liquid chromatography (HPLC) over a period of time. N-chlorophenylalanine (mono-N-chlorinated amino acid) and then phenylacetaldehyde were the major products formed for the lower chlorine to nitrogen molar ratios. For Cl/N molar ratios of 1 and beyond, phenylacetonitrile and N-chlorophenylacetaldimine appeared and increased with the chlorination level. N-chlorophenylacetaldimine was quantified by using its difference of stability in various organic solvents. Our attention was first directed to the monochlorinated derivative but further examination indicated that it could not be responsible for odor troubles: it dissociated before reaching the consumer's tap and it was produced at consistently low yields under conditions relevant to drinking water treatment. On the contrary, chloroaldimine appeared to be a very odorous and water-stable product: it strongly smells of swimming pool with a floral background. The odor detection threshold is about 3 microg x L(-1) and it can persist for more than one week at 18 degrees C. It is now suspected of being a source of off-flavor concerns among consumers.