UHPLC-PDA-ESI-TOF/MS metabolic profiling and antioxidant capacity of arabica and robusta coffee silverskin: antioxidants vs phytotoxins

A deeper knowledge of the chemical composition of coffee silverskin (CS) is needed due to the growing interest in its use as a food additive or an ingredient of dietary supplements. Accordingly, the aim of this paper was to investigate the metabolic profile of aqueous extracts of two varieties of CS, Coffee arabica (CS-A), Coffee canephora var. robusta (CS-R) and of a blend of the two (CS-b) and to compare it to the profile of Coffee arabica green coffee (GC). Chlorogenic acids, caffeine, furokauranes, and atractyligenins, phytotoxins not previously detected in CS, were either identified or tentatively assigned. An unknown compound, presumably a carboxyatractyligenin glycoside was detected only in GC. Caffeine and chlorogenic acids were quantified while the content of furokauranes and atractyligens was estimated. GC and CS were also characterized in terms of total polyphenols and antioxidant capacity. Differences in the metabolites distribution, polyphenols and antioxidant capacity in CG and CS were detailed

Encapsulation of antioxidant phenolic compounds extracted from spent coffee grounds by freeze-drying and spray-drying using different coating materials

Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.foodchem.2017.05.142.Freeze-drying and spray-drying techniques were evaluated for encapsulation of phenolic compounds (PC) extracted from spent coffee grounds. Additionally, the use of maltodextrin, gum arabic and a mixture of these components (ratio 1:1) as wall material to retain the PC and preserve their antioxidant activity was also assessed. The contents of PC and flavonoids (FLA), as well as the antioxidant activity of the encapsulated samples were determined in order to verify the efficiency of each studied condition. Additional analyses for characterization of the samples were also performed. Both the technique and the coating material greatly influenced the encapsulation of antioxidant PC. The best results were achieved when PC were encapsulated by freeze-drying using maltodextrin as wall material. Under these conditions, the amount of PC and FLA retained in the encapsulated sample corresponded to 62% and 73%, respectively, and 73-86% of the antioxidant activity present in the original extract was preserved.This work was supported by the Science and Technology Foundation of Portugal (FCT - grant SFRH/BD/80948/2011); the Strategic Project (PEst-OE/EQB/LA0023/2013); and the Project ‘‘BioInd - Biotechnology and Bioengineering for improved Industrial and Agro-Food processes” Co-funded by the Programa Operacional Regional do Norte (ON.2 – O Novo Norte), QREN, FEDER (Ref. NORTE-07-0124-FEDER-000028).info:eu-repo/semantics/publishedVersio

Three-dimensional fabrication of sub-micron optical waveguides in PDMS and other polymer materials

Optical waveguides are one of the most important photonic components. They are indispensable tools in many of todayâs technologies because of their capacity of guiding light. In particular, compact, low loss, flexible polymer optical waveguides are crucial in optofluidic and microfluidic devices for a dense integration of optical functionalities. The sought after suitable materials and innovative fabrication techniques to achieve low loss long polymer optical waveguides and interconnects has proven to be challenging. In a fiber optic endoscope, thousands of single-mode (SM) optical fibers acting as single pixels are closely packed together, delivering the local information to a camera chip. Biocompatible polymer-based waveguides increasingly became valid alternatives to silica fibers to deliver and collect light for optical diagnosis, therapy and surgery. In particular, polydimethylsiloxane (PDMS) is well known to be a suitable polymer for biomedical implantation devices, thanks to its excellent physical and chemical properties. In this thesis, I demonstrate the fabrication of compact optical waveguides in PDMS through multiphoton laser direct writing (MP-LDW). The core of this research consists of the investigation of suitable combinations of monomer and PI capable of efficient photopolymerization in a cured PDMS matrix. We achieved, for the first time, the photoinitiator-free fabrication of optical waveguides employing phenylacetylene as the photosensitive monomer via multi-photon absorption. Because of the dense Ï-electrons in phenylacetylene, we achieved a high refractive index contrast (În ⥠0.06) between the waveguide core and the PDMS cladding. This allowed for efficient waveguiding at a core size of 1.3-µm with a measured loss of 0.03 dB/cm in the spectral band of 650-700 nm. Motivated by the need of minimizing self-focusing, we investigated alternative chemical schemes and demonstrated the fabrication of submicron optical waveguides in PDMS using divinylbenzene (DVB) as the monomer through two-photon polymerization (2PP). We show that the commercial oxime ester photoinitiator Irgacure OXE02 is suitable for triggering the DVB polymerization, resulting in a stable and controllable fabrication process for the fabrication of defect-free, 5-cm long waveguides. Moreover, I present the methodologies we have developed for the fabrication of polymer rectangular step-index (STIN) optical waveguides using a commercial 3D printing system (Photonic Professional GT, Nanoscribe GmbH), using the proprietary IP-dip resist. We performed a full calibration and implemented a printing strategy for the fabrication of a 720 ÎŒm long SM-fiber bundle. We characterized it in terms of refractive index, transmission loss and imaging capabilities. We further demonstrate how a convolutional neural network (CNN) can reconstruct the original images from a scrambled output from the waveguide bundle due to crosstalk. To achieve this, we have constructed a CNN of the U-net type and trained the network with the input images and their corresponding output from the bundle. Overall, the presented work provides innovative materials and new insights into the fabrication of polymer optical microstructures, opening new scenarios for future technological development in the field of microfabrication using MP-LDW. We expect such waveguides will receive a wide range of applications in biosensors, microfluidic flow cytometry and wearable photonic devices

Internet communications : a challenge for Legislators. by Gianpaolo Panusa

tag=1 data=Internet communications : a challenge for Legislators. by Gianpaolo Panusa tag=2 data=Panusa, Gianpaolo tag=3 data=Canadian Parliamentary Review, tag=4 data=17 tag=5 data=3 tag=6 data=Autumn 1994 tag=7 data=26-28. tag=8 data=TECHNOLOGY tag=10 data=Policy issues between jurisdictions can be dealt with more effectively when parliamentarians can utilize instantaneous methods of communication. This article looks at both "one-way" communication for information retrieval and possibilities for "two-way" communication between parliamentarians across the county. tag=11 data=1994/6/9 tag=12 data=94/0517 tag=13 data=CABPolicy issues between jurisdictions can be dealt with more effectively when parliamentarians can utilize instantaneous methods of communication. This article looks at both "one-way" communication for information retrieval and possibilities for "two-way" communication between parliamentarians across the county

UHPLC-PDA-ESI-TOF/MS metabolic profiling of aqueous extracts of Arabica and Robusta Coffee Silverskin: not only natural antioxidants.

Coffee wastes and by-products from coffee industry are a source of contamination and a serious environmental problem, being mainly unutilized, discharged to the environment or burned. This promoted the interest of researchers in the characterization of wastes and by-products as coffee silverskin (CS, the tegument covering the coffee beans) to evaluate the possibility of reusing them. The high content of caffeine (CAF) and chlorogenic acids (CGAs) in CS and a significant antioxidant activity make them attractive for the recovery of natural antioxidants to be used as food supplements, dietary additives or cosmetic ingredients. The presence of phytotoxins and miycotoxins in green and roasted coffee beans, in CS and in dietary supplements containing green coffee (GC) extracts has recently been reported suggesting that a deeper knowledge of the metabolic profile of CS is required in order to evaluate advantages and risks associated with its consumption. In the present study, a comprehensive UHPLC-PDA-ESI-TOF/MS metabolic profiling of aqueous extracts of Arabica (CS-A) and Robusta (CS-R) CS was carried out. CS-A and CS-R were also characterized in terms of total polyphenols, flavonoids and antioxidant activity. The results were compared to those of Arabica GC aqueous extracts. Caffeic acid (CA) derivatives were found as the main CGAs in GC and CS, and the content of both CAF and CGAs followed the order GC >> CS, with CS-R > CS-A. Furokauranes as mozambioside and mascaroside, not previously reported in CS, were found and their levels in CS-A were much higher than in CS-R. The aglycone of mozambioside, not previously reported in coffee, was also evidenced. Atractyligenin and differently glycosilated derivatives were detected in GC and CS, the estimated content being CS-A >> CS-R

Direct HPLC enantioseparation of chemopreventive chiral isothiocyanates sulforaphane and iberin on immobilized amylose-based chiral stationary phases under normal-phase, polar organic and aqueous conditions

Sulforaphane and iberin are promising chemopreventive chiral phytochemicals. The chirality of these organic isothiocyanates is due to the presence of a stereogenic sulfur atom. Investigations of the effectiveness of single enantiomers as chemoprotective agents highlight the key role played by sulfur chirality on biological activity. The predominant native (R)-enantiomer is active whereas the (S)-counterpart is inactive or poorly active. Here, we provide an enantioselective method for the direct and complete resolution of both chiral sulfoxides by high-performance liquid chromatography on immobilized amylose-derived chiral stationary phases. A set of five different columns was investigated utilizing normal-phase, polar organic and aqueous conditions. The effect of the composition of mobile phase on enantioselectivity and retention was carefully evaluated. U-shape retention maps, which are indicative of a double and competitive hydrophilic interaction liquid chromatography and reversed-phase liquid chromatography retention mechanism, were established by recording the retention factors of the enantiomers of sulforaphane on the Chiralpak IA-3 and Chiralpak IG-3 chiral stationary phases varying progressively the water content in the water-acetonitrile mobile phases

Hemoglobin glutathionylation can occur through cysteine sulfenic acid intermediate : electrospray ionization LTQ-Orbitrap hybrid mass spectrometry studies

Glutathionylated hemoglobin (Hb-SSG) is now recognized as a promising biomarker of systemic oxidative stress. Aim of this study is to gain a mechanistic insight into its formation. The ability of GSSG to form Hb-SSG through a thiol-disulfide exchange mechanism was firstly examined. For this purpose, GSSG (ranging from 0.23 to 230 \u3bcmol/g Hb, 15 \u3bcM\u201315 mM final concentrations) was incubated with 1 mM Hb and the relative content of Hb-SSG determined by direct infusion mass spectrometry (Orbitrap as analyzer). No detectable Hb-SSG was observed at a GSSG concentration range found in physiopathological conditions (0.13\u20130.23 \u3bcmol/g Hb). To reach a detectable Hb-SSG signal, the GSSG concentration was raised to 2.3 \u3bcmol/g Hb (0.5% relative abundance). The relative content of Hb-GSSG dose-dependently increased to 6% and 11% at 77 and 153 \u3bcmol/g Hb, respectively. The second step was to demonstrate whether Hb-SSG is formed through a sulfenic acid intermediate, a well-recognized mechanism of S-protein glutathionylation. Cys \u3b293 sulfenic acid was found to be formed by oxidizing Hb with 1 mM H2O2, as demonstrated by direct infusion and LC\u2013ESI-MS/MS experiments and using dimedone as derivatazing agent. When H2O2-treated Hb was incubated with physiological concentrations of GSH (9 \u3bcmol/g Hb), the corresponding Hb-SSG form was detected, reaching 15% of relative abundance. In summary, we here demonstrate that Hb glutathionylation can occur through a Cys sulfenic acid intermediate which is formed in oxidizing conditions. Hb glutathionylation is also mediated by a thiol-disulfide transfer mechanism, but this requires a concentration of GSSG which is far to be achieved in physiopathological condition