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    Chemical and biological insights on aronia stems extracts obtained by different extraction techniques: From wastes to functional products
    (ELSEVIER SCIENCE BV, 2017) Cvetanovic, Aleksandra; Svarc-Gajic, Jaroslava; Zekovic, Zoran; Maskovic, Pavle; Durovic, Sasa; Zengin, Gökhan; Delerue-Matos, Cristina
    The present study aimed to evaluate chemical and biological potential of aronia stems for providing new raw material for food and pharmaceutical industries. Aqueous extracts of aronia stems were prepared by three different techniques (microwave-assisted, ultrasound-assisted and subcritical water extraction). For biological activities, antioxidant, antimicrobial and cytotoxic activities were evaluated. For chemical characterisation, phenolic compounds and essential elements were analysed as well as total phenolic contents. Subcritical water extracts exhibited the strongest antioxidant activity with the highest content of phenolics. Minimum inhibitory concentrations for analysed extracts were in the range from 9.76 to 156.25 mu g/mL in antimicrobial assays. The extracts exerted prominent cytotoxicity against different cell lines. Rutin was detected as the major compound in the studied extracts and these extracts were also rich in essential elements. Our study suggested that subcritical water extract of aronia stem could be considered as a new raw material in developing novel functional/industrial products.
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    Effects of Orange Leaves Extraction Conditions on Antioxidant and Phenolic Content: Optimization Using Response Surface Methodology
    (TAYLOR & FRANCIS INC, 2018) Uysal, Şengül; Cvetanovic, Aleksandra; Zengin, Gökhan; Durovic, Sasa; Zekovic, Zoran; Aktümsek, Abdurrahman
    In the last few years, bioactive components or their extraction techniques are gaining special interest in scientific areas. In this framework, orange leaves were used for preparation of extracts with high content of biologically active compounds. To optimize the extraction process, three levels and three variables of Box-Behnken design with response surface methodology were applied. Investigated responses were the total phenolic content (TPC), 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, cupric ion reducing antioxidant capacity (CUPRAC), and ferric reducing antioxidant power (FRAP). Independent variables were methanol concentration (10-90%), temperature (20-60 degrees C), and extraction time (60-180min). Experimentally obtained results were fit into a second-order polynomial model with multiple regression. Analysis of variance was used to estimate model fitness and determine optimal conditions for processing. Estimated optimal conditions were 90% methanolic solution, 60 degrees C and 180min using these parameters; the predicted values of investigated responses were 43.19mg GAE/g (GAE: gallic acid equivalents), 43.04mg TE/g (TE: trolox equivalents), 139.34 and 93.76mg TE/g for TPC, DPPH, CUPRAC, and FRAP, respectively. The obtained optimal conditions could be considered as an alternative strategy for developing novel functional products.
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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.
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    Multidirectional Approaches on Autofermented Chamomile Ligulate Flowers: Antioxidant, Antimicrobial, Cytotoxic and Enzyme Inhibitory Effects
    (ELSEVIER, 2019) Cvetanovic, Aleksandra; Zekovic, Zoran; Zengin, Gökhan; Maskovic, Pavle; Petronijevic, Mirjana; Radojkovic, Marija
    In the frame of the present paper the enzymatic transformation of apigenin-glucosides into free aglycone was achieved by autofermentation of chamomile ligulate flowers (CLF). Antioxidant properties of the autofermented CLF (A-CLF) extract were evaluated by their radical scavenging activity against hydroxyl radicals and inhibition of lipid peroxidation. Obtained results showed that A-CLF extract in a concentration of 0.84 mg/mL was able to inhibit 50% of hydroxyl radicals, while IC50 value in the case of inhibition of lipid peroxidation was 5.21 mg/mL. Antimicrobial activity was done by measuring minimal inhibitory concentration (MIC) values for eight microbial strains. Obtained MIC values (9.75-156.25 mu g/mL) confirmed high antibacterial and antifungal activities of the extract. Cytotoxic activity was done by using three histological different cell lines: Hep2C; RD and L2OB. Obtained IC50 values for these cell lines were: 28.72; 17.31 and 10.92, respectively. Furthermore, in vitro investigation of the A-CLF ability to inhibit selected enzymes (alpha-amylase, alpha-glucosidase, tyrosinase) was done as well. Determined activities against alpha-amylase and alpha-glucosidase were 0.94 and 3.24 mmol ACAE/g, respectively. Further, measured activity against tyrosinase was 0.69 mg KAEs/g indicating high enzyme-inhibitory activity of examined sample. Results demonstrated that A-CLF extracts showed considerable pharmacological activity. (c) 2018 SAAB. Published by Elsevier B.V. All rights reserved.
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    A new source for developing multi-functional products: biological and chemical perspectives on subcritical water extracts of Sambucus ebulus L.
    (WILEY, 2018) Cvetanovic, Aleksandra; Zekovic, Zoran; Svarc-Gajic, Jaroslava; Razic, Slavica; Damjanovic, Ana; Zengin, Gökhan; Delerue-Matos, Cristina
    BACKGROUND: To obtain bioactive fractions from plant material subcritical water is notably advantageous in comparison to any other technique. Excellent solvating properties and selectivity combined with finely tuned reactivity of subcritical water enable exploitation of the potential of plants. Herein subcritical water extraction was used for recovery of bioactive compounds from leaves, roots and fruits of Sambucus ebulus L. Extracts obtained were characterized in terms of biological and chemical fingerprints. RESULTS AND DISCUSSIONR: esults obtained by using several antioxidant assays that focused on different mechanisms showed that subcritical water extracts of Sambucus ebulus were powerful antioxidants. Enzyme inhibitory effects were tested against alpha-amylase, alpha-glucosidase and tyrosinase, and the results showed the anti-diabetic potential of the extracts as well as its possible use with skin disorders. Antiproliferative properties were detected on three cell lines (A-549; LS-174 T; HeLa) and showed prominent cytotoxicity against all tumor cell lines. Inhibitory concentrations obtained were in the range 0.58-8.10 mu g mL(-1). Generally, the SCW extracts from leaves exhibited stronger biological activities with higher levels of phenolic compounds compared with the roots and fruits of Sambucus ebulus. Gallic acid, catechin and caffeic acid were identified as major components in these extracts and these components seem to relate with observed biological activity. CONCLUSION: The results obtained suggest that Sambucus ebulus has great potential for preparing new phyto-pharmaceuticals and functional food ingredients. (C) 2017 Society of Chemical Industry.
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    Optimization of maceration conditions for improving the extraction of phenolic compounds and antioxidant effects of Momordica Charantia L. leaves through response surface methodology (RSM) and artificial neural networks (ANNs)
    (TAYLOR & FRANCIS INC, 2019) Uysal, Şengül; Cvetanovic, Aleksandra; Zengin, Gökhan; Zekovic, Zoran; Mahomoodally, Mohamad Fawzi; Bera, Oskar
    The main goals of this research were the chemical and biological characterization of the bitter melon (Momordica charantia) isolate obtained by traditional (maceration) extraction, as well as optimization of this process using response surface methodology (RSM) and artificial neural networks (ANNs). Experiments were performed using Box-Behnken experimental design on three levels and three variables: extraction temperature (20 degrees C, 40 degrees C, and 60 degrees C), solvent concentration (30%, 50%, and 70%) and extraction time (30, 60, and 90 min). The measurements consisted of 15 randomized runs with 3 replicates in a central point. The antioxidant activity of obtained extracts was determined by the 1,1-diphenyl-2-picrylhydrazyl (DPPH), cupric ion reducing antioxidant capacity (CUPRAC) and ferric reducing antioxidant power (FRAP) assays while chemical characterization was done in terms of the total phenolic content (TPC). The methodology shows positive influence of solvent concentration on all four observed outputs, while temperature showed a negative impact. RSM showed that the optimal extraction conditions were 20 degrees C, 70% methanol, and an extraction time of 52.2 min. Under these conditions, the TPCs were 20.66 milligrams of gallic acid equivalents (mg GAE/g extract), DPPH 30.22 milligrams of trolox equivalents (mg TE/g extract), CUPRAC 67.78 milligrams of trolox equivalents (mg TE/g extract), and FRAP 45.48 milligrams of trolox equivalents (mg TE/g extract). The neural network coupled with genetic algorithms (ANN-GA) was also used to optimize the conditions for each of the outputs separately. It is anticipated that results reported herein will establish baseline data and also demonstrate that that the present model can be applied in the food and pharmaceutical industries.