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    The influence of the extraction temperature on polyphenolic profiles and bioactivity of chamomile (Matricaria chamomilla L.) subcritical water extracts
    (ELSEVIER SCI LTD, 2019) Cvetanovic, Aleksandra; Svarc-Gajic, Jaroslava; Zekovic, Zoran; Jerkovic, Jelena; Zengin, Gökhan; Gasic, Urog; Tesic, Zivoslav; Mašković, Pavle; Soares, Cristina; Barroso, M. Fatima; Delerue-Matos, Cristina; Đurović, Saša
    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 degrees 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 mu g/mL), whereby temperature of 150 degrees C was optimal. On the other hand, the extracts obtained at 115 degrees C showed highest cytotoxicity. Inhibition of alpha-amylase and alpha-glucosidase was the highest at 65 and 85 degrees C, i.e. 0.51 and 4.13 mmolAE/g, respectively. Activity against tyrosinase was the highest at 210 degrees C (17.92 mgKAE/g). The data showed that different non-phenolic compounds may also participate in bio-activities of the extracts.
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    Isolation of apigenin from subcritical water extracts: Optimization of the process
    (ELSEVIER SCIENCE BV, 2017) Cvetanovic, Aleksandra; Svarc-Gajic, Jaroslava; Gasic, Uros; Tesic, Zivoslav; Zengin, Gökhan; Zekovic, Zoran; Durovic, Sasa
    Apigenin is a phytochemical which has been associated with numerous beneficial health effects. However, due to its low concentration and poor bioavailability, isolation from natural sources is very difficult. Subcritical water (SCW) is an excellent solvent for the extraction of moderately polar and non-polar flavonoids. Carefully balanced moderate hydrolytical potential of SCW was used in this work to liberate apigenin from its bound forms. In this research simultaneous extraction and hydrolysis of apigenin bound forms from chamomile have been performed. Optimal operation parameters for maximum yields of apigenin have been investigated and defined (solvent-to-sample ratio 1:30; agitation rate 3 Hz; pressure 45 bar; temperature 115 degrees C; time 30 min). Apigenin was further isolated in its pure form from water extracts obtained under optimal conditions using column chromatography. The purity of isolated compound was confirmed by spectroscopic analysis. Biological activity of extracts obtained under optimal conditions were determined as well. In order to identify polyphenolic compounds UHPLC-HESI-MS/MS analysis was performed. (C) 2016 Elsevier B.V. All rights reserved.