Influence des conditions de sechage sur la couleur des carottes. Optimisation des methodes d'analyse des pigments

SIGLEINIST T 75382 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Supercritical fluid chromatography for the analysis of natural dyes: From carotenoids to flavonoids

Plant-derived natural dyes are used in a variety of formulated products, from food to cosmetics and pharmaceutics. In addition to their color, they also provide some bioactivity. While they are mostly analyzed with high-performance liquid chromatography, supercritical fluid chromatography was also employed for several dye families, mostly for carotenoids and chlorophylls, and more recently for anthraquinones and flavonoids. These supercritical fluid chromatography methods are described in this review. Because the dyes have different structures and structural variations (polarity, isomers, etc.), the best chromatographic system to achieve their separation is not always the same. Hydrophobic stationary phases are preferred for the most hydrophobic dyes (chlorophylls and carotenoids) while polar stationary phases are preferred for the polar dyes (anthraquinones and flavonoids). Regarding the mobile phase composition, chlorophylls and carotenoids are best eluted with moderate proportions of co-solvent in CO2 (about 40%), while the most polar glycosylated flavonoids require higher proportions of co-solvent and acidic additives. Because dyes are colorful, ultraviolet-visible detection is often sufficient, while mass spectrometry offers additional structural information. Furthermore, fundamental information can also be gained through chromatographic analysis of dyes: either solubility in supercritical fluids, in view of their extraction, or retention behavior providing an understanding of stationary phase properties

Anatomie palpatoire du chat

L'anatomie palpatoire a pour but de mettre en évidence par une exploration manuelle tous les différents reliefs anatomiques normalement accessibles à la palpation. L'auteur décrit donc une méthode de palpation, associant gestes et sensations perçues pour l'ensemble des reliefs anatomiques les plus superficiels, applicable sur la plupart des chats adultes sains et vigiles. Quelques applications de cette anatomie palpatoire en médecine vétérinaire courante y sont également décrites pour souligner l'importance de son acquisition.NANTES-Ecole Nat.Vétérinaire (441092302) / SudocSudocFranceF

Selection of SFC stationary and mobile phases

Supercritical fluid chromatography (SFC) benefits from an extensive toolbox to achieve achiral or chiral separations. The most powerful tools in this box arise from the diversity of stationary phases available and the wide range of polarities achievable through manipulation of both the stationary phase and mobile phase composition. These parameters are the main topic of this chapter, with a particular focus on compounds of pharmaceutical interest, whether they be small chemicals, biopharmaceuticals, or traditional medicine from natural products. Secondary tools like column oven temperature, back-pressure applied to maintain the fluid in the supercritical or subcritical state, and the pumping flow rate are all useful when fine optimization is required. Their effects will also be described. Finally, the possibility to predict the outcome of SFC separations will also be briefly discussed

Optimization of supercritical fluid extraction of polar flavonoids from Robinia pseudoacacia L. heartwood

The black locust, known as an invasive species, represent many advantages, mainly due to its rapid growth rate and its richness with interesting flavonoids. In this study, supercritical fluid extraction of the two main flavonoids dihydrorobinetin and robinetin, was optimized using a three level Box-Behnken response surface design. The conditions investigated to influence the extraction yield of these flavonoids were temperature (40–80 °C), pressure (10–20 MPa) and modifier’s percentage EtOH:H2O 80:20 (10 %−30 %). The response was quantified using an UHPLC-DAD optimized chromatographic method. The results showed the influence of the extraction conditions on the yield of the molecules of interest. The data were fitted into a second-order polynomial equation, the multiple regression analysis showed a high determination coefficient value (R2) of 0.93. The optimal extraction conditions were 10 MPa, 80 °C and extraction phase composition of CO2:EtOH:H2O 80:16:4 for 30 min. These conditions allowed for the recovery 49.2 mg of flavonoids for 1 g of dried wood powder

Supercritical Fluid Extraction (SFE) of Polar Compounds from Camellia sinensis Leaves: Use of Ethanol/Water as a Green Polarity Modifier

International audienceThe use of bioactive plant extracts in cosmetic products is a common practice. Most of these extracts are obtained by maceration in organic solvents, and depending on which solvents are used, the polarity and the structure of the target molecules will vary. Polyphenols are polar compounds that often display antioxidant and/or antibacterial activities. To extract them, ethanol/water mixtures are usually selected as green solvents. This solid–liquid extraction (assisted or not) requires the use of high volumes of solvents and many additional steps like mixing, agitation, filtration, and evaporation. Alternatively, supercritical carbon dioxide (SC-CO2) offers many benefits for plant extraction: economical, non-toxic, and naturally concentrated extracts. However, its low polarity is not suitable to solubilize polar compounds. In this study, an experimental design was used to optimize supercritical fluid extraction (SFE) of caffeine and catechins from Camellia sinensis. Catechins are recognized for skin care use (antioxidant) and caffeine is also used for its skin care properties and to prevent excess storage of fat in cells. The temperature, modifier content, and water additive percentage were used as independent variables. The results showed that while the temperature was an insignificant parameter, a higher percentage of water (up to 20% in ethanol) and modifier favored the extraction of the polar target molecules. Additionally, the SFE results were compared with ultrasound-assisted extraction (UAE). Finally, a sequential selective extraction of caffeine from catechins is also presented