Zoran Zeković

Modeling and optimization of ultrasound-assisted extraction of polyphenolic compounds from Aronia melanocarpa by-products from filter-tea factory

Aronia melanocarpa by-product from filter-tea factory was used for the preparation of extracts with high content of bioactive compounds. Extraction process was accelerated using sonication. Three level, three variable face-centered cubic experimental design (FCD) with response surface methodology (RSM) was used for optimization of extraction in terms of maximized yields for total phenolics (TP), flavonoids (TF), anthocyanins (MA) and proanthocyanidins (TPA) contents. Ultrasonic power (X₁: 72-216 W), temperature (X₂: 30-70 °C) and extraction time (X₃: 30-90 min) were investigated as independent variables. Experimental results were fitted to a second-order polynomial model where multiple regression analysis and analysis of variance were used to determine fitness of the model and optimal conditions for investigated responses. Three-dimensional surface plots were generated from the mathematical models. The optimal conditions for ultrasound-assisted extraction of TP, TF, MA and TPA were: X₁=206.64 W, X₂=70 °C, X₃=80.1 min; X₁=210.24 W, X₂=70 °C, X₃=75 min; X₁=216 W, X₂=70 °C, X₃=45.6 min and X₁=199.44 W, X₂=70 °C, X₃=89.7 min, respectively. Generated model predicted values of the TP, TF, MA and TPA to be 15.41 mg GAE/ml, 9.86 mg CE/ml, 2.26 mg C3G/ml and 20.67 mg CE/ml, respectively. Experimental validation was performed and close agreement between experimental and predicted values was found (within 95% confidence interval).

Supercritical Extraction of Thyme (Thymus vulgaris L.)

SummaryChromatographic methods for the qualitative and quantitative analysis of thyme (Thymus vulgaris L.) extracts (essential oil obtained by steam distillation and extracts obtained by carbon dioxide supercritical fluid extraction and methylene chloride) are described. The composition of extracts obtained at different pressures (from 80 bar to 400 bar) and constant temperature (40°C) is discussed. The extraction system thyme— supercritical carbon dioxide was modelled by empirical equations defining the dependence of the total extract (TE) solubility and thymol solubility in CO2 on the density of carbon dioxide.

Free radical scavenging activity, total phenolic and flavonoid contents of mulberry (Morus spp. L., Moraceae) extracts

Mulberry (Morus spp. L., Moraceae) fruits, leaves, bark and branch have been used in traditional medicine as diuretic, hypoglycemic and hypotensive. The mechanism of their effects is correlated with the content of active components. Objective of this work was to evaluate and compare antioxidant properties of different extracts of two Morus species growing in Serbia: Morus alba L. (white mulberry) and Morus nigra L. (black mulberry). Potential antioxidant activity, content of antioxidant compounds (phenolics and flavonoids) and radical scavenging capacity, tested by DPPH method, were evaluated. The phenolic and flavonoid composition of different Morus extracts was determined by the HPLC method. The extracts prepared from fruits, leaves and roots of M. alba and M. nigra exhibited different characteristics. The highest extraction yield was achieved by M. alba leaves extraction (23.40%). M. nigra roots extract shown the highest total phenolics (186.30 mg CAE/g), while highest total flavonoids content (67.37 mg RE/g) was determined for M. nigra leaves extracts. In addition, black mulberry leaves extracts with the highest antioxidant activity had the highest phenolic acids contents. The dominant phenolic components in the samples were rutin and chlorogenic acid. All investigated mulberry dry extracts shown high content of phenolic compounds and significant antioxidant activity. This work contributes to knowledge of the antioxidant properties of Morus species. The obtained results may be useful in the evaluation of new dietary supplements and food products.

Behavior of (–)-α-Bisabolol and (–)-α-Bisabololoxides A and B in Camomile Flower Extraction with Supercritical Carbon Dioxide

Abstract A systematic study of the extraction behavior of selected components of camomile flowers in extraction with supercritical carbon dioxide was carried out. (–)-α-Bisabolol and its A and B oxides, which have a wide importance in pharmacology and standardization of camomile flower products, were selected. The dependence of the yield of selected components on the pressure and/or temperature of supercritical extraction was investigated. The results obtained were correlated.

Chromatography in our investigations of camomile (Matricaria chamomilla L.)

SummaryChromatographic methods for qualitative and quantitative analysis of non-volatile and volatile compounds of camomile (Matricaria chamomilla L.) are described. For determination of flavonoids of the apigenin series HPTLC and HPLC were used. To obtain standard samples of components of camomile oil semi-preparative TLC was used. Mass spectra of these standards were obtained to provide a data base. Qualitative and quantitative analysis of camomile oil compounds by GC-MS was then possible.

MODELING OF THE THYME-SUPERCRITICAL CARBON DIOXIDE EXTRACTION SYSTEM. I. THE INFLUENCE OF CARBON DIOXIDE FLOW RATE AND GRINDING DEGREE OF THYME

The influence of carbon dioxide flow rate and grinding degree of thyme on supercritical fluid extraction of thyme was investigated. The extraction rate of the pharmacologically important compound of thyme-thymol can be successfully expressed by analogy to first-order reaction kinetics. To model extraction of the thyme–supercritical carbon dioxide system, we used the Reverchon-Sesti Osseo equation as well as our modified equation.

Comparative analysis of antioxidant, antimicrobiological and cytotoxic activities of native and fermented chamomile ligulate flower extracts

AbstractMain conclusionThe work investigated differences in apigenin content, as well as in other compounds, and examined the chemical profiles, antioxidant, antimicrobial and cytotoxic effects of extracts obtained from native and fermented chamomile ligulate flowers. Chamomile (Chamomilla recutita L.) has a long history of being used as a medicinal plant due to many health benefits, including antiinflammatory, anticancer, antispasmodic, radical-scavenging effects and others. Apigenin is recognized as one of the most bioactive phenolic compounds in chamomile. In comparison to its bound forms, which include mostly apigenin-7-O-β-glucoside and various acylated forms, the aglycone is attributed with much higher bioactivity. Due to this fact, in this work ligulate florets of chamomile anthodium were subjected to a fermentation process using native chamomile enzymes to hydrolyze bound forms of apigenin to free aglycone. The contents of apigenin and apigenin-7-O-β-glucoside were determined in both fermented and nonfermented samples by UHPLC-MS–MS analysis to define the efficiency of conversion. After defining their chemical profiles, the extracts of fermented and nonfermented chamomile samples were also compared with respect to their antioxidant, antimicrobial and cytotoxic effects. The antioxidant effects of the obtained extracts were defined by electron spin resonance analysis for hydroxyl and superoxide radicals. The antimicrobial activity was defined for eight microbial strains, whereas cytotoxic activity was evaluated using two human cell lines (human cervix carcinoma and human rhabdomyosarcoma) and murine fibroblasts.

Modeling of the Thyme–Supercritical Carbon-Dioxide Extraction System. II. The Influence of Extraction Time and Carbon Dioxide Pressure

The influence of extraction time and carbon dioxide pressure (i.e., carbon dioxide density) on supercritical fluid extraction of thyme was investigated. For determination of obtained extracts, HPLC and GC-MS methods were used. To model extraction of the thyme–supercritical carbon dioxide system, we used the Reverchon-Sesti Osseo equation as well as our modified equation.

Optimization of microwave‐assisted extraction (MAE) of coriander phenolic antioxidants ‐ Response surface methodology approach

BACKGROUND Microwave-assisted extraction (MAE) of polyphenols from coriander seeds was optimized by simultaneous maximization of total phenolic (TP) and total flavonoid (TF) yields, as well as maximized antioxidant activity determined by 1,1-diphenyl-2-picrylhydrazyl and reducing power assays. Box-Behnken experimental design with response surface methodology (RSM) was used for optimization of MAE. Extraction time (X1 , 15-35 min), ethanol concentration (X2 , 50-90% w/w) and irradiation power (X3 , 400-800 W) were investigated as independent variables. Experimentally obtained values of investigated responses were fitted to a second-order polynomial model, and multiple regression analysis and analysis of variance were used to determine fitness of the model and optimal conditions. RESULTS The optimal MAE conditions for simultaneous maximization of polyphenol yield and increased antioxidant activity were an extraction time of 19 min, an ethanol concentration of 63% and an irradiation power of 570 W, while predicted values of TP, TF, IC50 and EC50 at optimal MAE conditions were 311.23 mg gallic acid equivalent per 100 g dry weight (DW), 213.66 mg catechin equivalent per 100 g DW, 0.0315 mg mL(-1) and 0.1311 mg mL(-1) respectively. CONCLUSION RSM was successfully used for multi-response optimization of coriander seed polyphenols. Comparison of optimized MAE with conventional extraction techniques confirmed that MAE provides significantly higher polyphenol yields and extracts with increased antioxidant activity.

Pigment content and fatty acid composition of paprika oleoresins obtained by conventional and supercritical carbon dioxide extraction

An experiment was conducted to examine the influence of conventional and supercritical extraction of ground paprika (“Aleva N.K.” variety) on the quality of paprika oleoresin. Paprika was extracted using hexane as an organic solvent and supercritical carbon dioxide at 20, 30 and 40 MPa. The extraction yields were 12.8, 10.6, 10.6 and 10.3%, respectively. It was confirmed that the organic solvent was less selective than the supercritical carbon dioxide. The analyses of fatty acid composition showed that oleoresin consisted mostly of linoleic acid. The highest pigment content was found in the conventional oleoresin, 31,476 mg/kg. Among supercritical oleoresins, the richest in pigments was the one obtained at 40 MPa (14,134 mg/kg), 44.9% in comparison with the conventional.