Comparison of hydrodistillation (HD), microwave-assisted hydrodistillation (MHD) and supercritical fluid extraction (SFE) for the isolation of volatiles from chamomile flower

Chamomile flower (Matricariae flos) is a herbal drug used mainly because of antiphlogistic, spasmolytic and antimicrobial properties, which are related to the presence of volatile essential-oil constituents (α-bisabolol and its oxides, chamazulene, spiroethers) and non-volatile compounds, such as sesquiterpene lactones, flavonoids, and coumarins.                In the present work, we used hydrodistillation (HD; sample-to-solvent ratio 1:20, 2 h), microwave-assisted HD (MHD; sample-to-solvent ratio 1:20, 2 h, microwave power 180 W) and supercritical CO2 extraction (SFE; 40 °C, 100 bar, 3 h) to obtain isolates, from a commercially available chamomile flower tea. The composition of the isolates was analyzed using GC-MS. The obtained results of the relative content of the selected pharmacologically relevant constituents were as follows.                HD and MHD yielded 0.2% and 0.3% of isolates, respectively. A much higher yield was obtained in the case of SFE (3%). In HD and MHD isolates, which were qualitatively and quantitatively similar, oxygenated sesquiterpenes dominated (64.4-67.4%), with bisabolol oxides comprising 54.2-54.4% of the isolates. Among non-terpene constituents (17.0-19.9%), spiroethers were present with 10.0% and 11.7% of HD and MHD isolates, respectively. Chamazulene (4.8-4.9%) was the most abundant among sesquiterpene hydrocarbons (8.8-9.7%). On the other hand, non-terpene compounds (57.4%) were the most abundant class of constituents in SFE extract, and among them hydrocarbons comprised 45.0% of the extract, followed by 10.2% of spiroethers. Among the oxygenated sesquiterpenes (32.2%), SFE extract contained 25.8% of bisabolol oxides. In contrast to HD and MHD, SFE resulted in a low amount of chamazulene, but the extract contained 3.2% of valuable sesquiterpene lactones.                Having in mind that HD and MHD resulted in similar yields and compositions of the isolates, and that SFE gave a higher amount of the isolate with a unique composition, the choice of traditional vs modern technique for the preparation of chamomile isolates should be strongly dependent on the specific use of the final product and in that sense carefully evaluated

The influence of the extraction temperature on polyphenolic profiles and bioactivity of chamomile (Matricaria chamomilla L.) subcritical water extracts

The main goal of this research was to determine the relationship among chemical structure, bioactivity and temperature of chamomile during subcritical water extraction in isobaric conditions (45 bar) at seven different temperatures (65-210 °C). The influence of temperature on phenolic profiles was defined by UHPLC-HESI-MS/MS. The overall results indicate that the presence of conjugated double bonds, side chains, glucose moiety or ether moiety in molecules influence the efficiency of polyphenols' extraction in subcritical water. In terms of antioxidant activity, the extracts were the most active towards ABTS radicals (IC50 = 7.3-16.8 µg/mL), whereby temperature of 150 °C was optimal. On the other hand, the extracts obtained at 115 °C showed highest cytotoxicity. Inhibition of α-amylase and α-glucosidase was the highest at 65 and 85 °C, i.e. 0.51 and 4.13 mmolAE/g, respectively. Activity against tyrosinase was the highest at 210 °C (17.92 mgKAE/g). The data showed that different non-phenolic compounds may also participate in bio-activities of the extracts.The present work was carried out within the projects of the Serbian Ministry of Education, Science and Technological Development, Serbia, (Projects No. TR31013 and 172017). The authors are grateful to Dr Dušan Adamović, Institute of Field and Vegetable Crops, Bački Petrovac, Serbia, for his support in supplying plant material.REQUIMTE received financial support from Programme PT2020 (NORTE-07-0124-FEDER-000069 and NORTE-01-0145-FEDER-000011-RL1-QUALIFOOD) and from FCT (UID/QUI/50006/2013- POCI/01/0145/FEDER/007265). M. Fátima Barroso would like to thank also to FCT for the post-doc fellowship (SFRH/BPD/78845/2011).info:eu-repo/semantics/publishedVersio

Mechanochemical Synthesis of TiO2-CeO2 Mixed Oxides Utilized as a Screen-Printed Sensing Material for Oxygen Sensor

TiO2 and CeO2 are well known as oxygen sensing materials. Despite high sensitivity, the actual utilization of these materials in gas detection remains limited. Research conducted over the last two decades has revealed synergistic effects of TiO2-CeO2 mixed oxides that have the potential to improve some aspects of oxygen monitoring. However, there are no studies on the sensing properties of the TiO2-CeO2 obtained by mechanochemical treatment. We have tested the applicability of the mechanochemically treated TiO2-CeO2 for oxygen detection and presented the results in this study. The sensing layers are prepared as a porous structure by screen printing a thick film on a commercial substrate. The obtained structures were exposed to various O2 concentrations. The results of electrical measurements showed that TiO2-CeO2 films have a significantly lower resistance than pure oxide films. Mixtures of composition TiO2:CeO2 = 0.8:0.2, ground for 100 min, have the lowest electrical resistance among the tested materials. Mixtures of composition TiO2:CeO2 = 0.5:0.5 and ground for 100 min proved to be the most sensitive. The operating temperature can be as low as 320 °C, which places this sensor in the class of semiconductor sensors working at relatively lower temperatures

Virtual histology study of atherosclerotic plaque composition in patients with stable angina and acute phase of acute coronary syndromes without ST segment elevation

Introduction. Rupture of vulnerable atherosclerotic plaques is the cause of most acute coronary syndromes (ACS). Postmortem studies which compared stable coronary lesions and atherosclerotic plaques in patients who have died because of ACS indicated high lipid-core content as one of the major determinants of plaque vulnerability. Objective. Our primary goal was to assess the potential relations of plaque composition determined by IVUS-VH (Intravascular Ultrasound - Virtual Histology) in patients with stable angina and subjects in acute phase of ACS without ST segment elevation. Methods. The study comprised of 40 patients who underwent preintervention IVUS examination. Tissue maps were reconstructed from radio frequency data using IVUS-VH software. Results. We analyzed 53 lesions in 40 patients. Stable angina was diagnosed in 24 patients (29 lesions), while acute phase of ACS without ST elevation was diagnosed in 16 patients (24 lesions). In the patients in acute phase of ACS without ST segment elevation IVUS-VH examination showed a significantly larger area of the necrotic core at the site of minimal lumen area and a larger mean of the necrotic core volume in the entire lesion comparing to stable angina subjects (1.84±0.90 mm2 vs. 0.96±0.69 mm2; p<0.001 and 20.94±15.79 mm3 vs. 11.54±14.15 mm3; p<0.05 respectively). Conclusion. IVUS-VH detected that the necrotic core was significantly larger in atherosclerotic lesions in patients in acute phase of ACS without ST elevation comparing to the stable angina subjects and that it could be considered as a marker of plaque vulnerability

Metoda za posmatranje i analizu protoka fluida u Si-Pyrex staklo opto-mikrofluidnim platformama

Ovo tehničko rešenje predstavlja razvoj metode za posmatranje i analizu protoka fluida u silicijum-Pyrex staklo opto-mikrofluidnim platformama. Metoda se zasniva na snimanju video zapisa pomoću metalografskog mikroskopa sa digitalnom kamerom dok se špric pumpama (syringe pump) definisano zadaje protok fluida kroz izrađenu platformu. Platforma se sastoji od mikrokanala koji su izrađeni procesima mikromašinstva, odnosno vlažnog hemijskog nagrizanja, i anodnog bondovanja silicijuma i Pyrex stakla. Kroz staklo platforme se posmatraju i snimaju protoci različitih fluida sa ili bez čestica u mikrokanalima. Mikrokanali mogu biti različitog dizajna i definisani u silicijumu i/ili Pyrex staklu. Validacija funkcije izrađene platforme (mikromiksera ili separatora čestica) vrši se analizom fotografija ili frejmova video zapisa pomoću odgovarajućih softverskih paketa, na primer ImageJ

Mechanochemical Synthesis of TiO2-CeO2 Mixed Oxides Utilized as a Screen-Printed Sensing Material for Oxygen Sensor

TiO2 and CeO2 are well known as oxygen sensing materials. Despite high sensitivity, the actual utilization of these materials in gas detection remains limited. Research conducted over the last two decades has revealed synergistic effects of TiO2-CeO2 mixed oxides that have the potential to improve some aspects of oxygen monitoring. However, there are no studies on the sensing properties of the TiO2-CeO2 obtained by mechanochemical treatment. We have tested the applicability of the mechanochemically treated TiO2-CeO2 for oxygen detection and presented the results in this study. The sensing layers are prepared as a porous structure by screen printing a thick film on a commercial substrate. The obtained structures were exposed to various O2 concentrations. The results of electrical measurements showed that TiO2-CeO2 films have a significantly lower resistance than pure oxide films. Mixtures of composition TiO2:CeO2 = 0.8:0.2, ground for 100 min, have the lowest electrical resistance among the tested materials. Mixtures of composition TiO2:CeO2 = 0.5:0.5 and ground for 100 min proved to be the most sensitive. The operating temperature can be as low as 320 &deg;C, which places this sensor in the class of semiconductor sensors working at relatively lower temperatures