Danijela A. Kostić

Reducing power and radical scavenging activity of four Parmeliaceae species

The methanol extracts of four Parmeliaceae lichens (Hypogymnia physodes, Evernia prunastri, Flavoparmelia caperata and Parmelia sulcata) were screened for antioxidant properties and total phenol content. The H. physodes extract was the most effective at reducing iron(III) and scavenging 1,1-diphenyl-2-picrylhydrazyl radicals, while the P. sulcata extract was the most effective in reducing molybdenum(VI) in an acidic medium. The E. prunastri and H. physodes extracts contained more Folin-Ciocalteu reagent reactive substances than the F. caperata and P. sulcata extracts. Significant activity of the H. physodes extract in DPPH and reducing Fe(III) assays suggest that this lichen can be considered as a potential source of antioxidants.

Xanthine Oxidase: Isolation, Assays of Activity, and Inhibition

Xanthine oxidase (XO) is an important enzyme catalyzing the hydroxylation of hypoxanthine to xanthine and xanthine to uric acid which is excreted by kidneys. Excessive production and/or inadequate excretion of uric acid results in hyperuricemia. This paper presents a detailed review of methods of isolation, determination of xanthine oxidase activity, and the effect of plant extracts and their constituents on it. Determining the content and activities of XO can be used for diagnostic purposes. Testing inhibition of XO is important for detection of potentially effective compounds or extracts that can be used to treat diseases that are caused by increased activity of XO. In vitro bioassays are used to examine test material for XO inhibition, as inhibitors of XO may be potentially useful for the treatment of gout or other XO induced diseases. Several authors reported on the XO inhibitory potential of traditionally used medicinal plants.

Polyphenol content and antioxidant activity of sour cherries from Serbia

The aim of this study is to evaluate the content of phenolics: the total phenols (TP), flavonoids (TF), anthocyanins (TA), as well as the total antioxidant capacity (TAC) in three sour cherry cultivars (Prunus cerasus L.) introduced to the southeast Serbia climate conditions. Among the researched sour cherries, ‘Oblacinska’ cultivar contained the highest amounts of all groups of phenolics, followed by ‘Cigancica’ > ‘Marela’. A significant difference were observed in the phenolic content among different cultivars and growing seasons (p<0.05), and the phenolic compounds were significantly higher in the growing season 2009. The examined cultivars possess a high antioxidant capacity, and all phenolics of highy correlation with TAC. The following compounds were identified and quantified using HPLC-DAD: 4 anthocyanins, the most abundant of which was cyaniding-3-glucoside in ‘Marela’ and ‘Oblacinska’, and cyanidin-3-glucosylrutinoside in ‘Cigancica’, and 4 hydroxycinnamic acids, the most abundant of which was neochlorogenic acid in all sour cherry cultivars. The growing and ripening process on the tree of sour cherry cv. Oblacinska was evaluated, also. The results showed significant increases in total phenols during the ripening, the total anthocyanins and total antioxidant capacity and 4 quantified anthocyanins, however the neochlorogenic acid decreased during the ripening. The study indicated that the growing and climate conditions in southeast Serbia are convenient for introducing sour cherry cultivars.

Spectrophotometric determination of microamounts of quercetin based on its complexation with copper(II)

The complexation process of the transition metal Cu(II) with quercetin was studied. The investigation was conducted spectrophotometrically in ethanol at the maximum absorption wavelength of 458.5 nm. Cu(II)—quercetin complex composition (1: 1) was determined using the Job, Harvey—Manning, and mole ratio methods. Complex stability constant was calculated by the Job and mole ratio methods and the respective logarithm values were 7.53 ± 0.25 and 7.44 ± 0.03. A new method for quantitative determination of the quercetin content in solution was developed in this work. At the optimal conditions quercetin was determined in concentrations ranging from 0.202 to 1.006 µg cm−3 with relative standard error of 2.5 % to 5.5 %. The lower detection limit was 0.067 µg cm−3. The method was found very accurate, reproducible, and sensitive, capable to determine microamounts of quercetin in pharmaceutical preparations.

Statistical characteristics of selected elements in vegetables from Kosovo

Zinc, copper, iron, chromium and cobalt are essential elements for human health, showing toxicity only in high concentrations, while lead and cadmium are extremely toxic even as traces. Therefore, it is important to monitor the contents of toxic metals in vegetables. Large number of vegetables is grown and used in nutrition, in Kosovo. The concentrations of selected elements in vegetables (radish, onion, garlic and spinach) from Kosovo were determined using ICP-OES method. Oral intake of metals and health risk index were calculated. Statistical analysis indicated numerous positive correlations between concentrations of selected elements in vegetables. As a result of principal component analysis, 15 new variables were obtained which were characterized by eigenvalues. The sequence of health quotients for the heavy metals followed the decreasing order Zn = Mn > Pb > Cu > Ni > Fe > Cd > Co > Cr. The health quotients for all investigated heavy metals were below 1 (one), which is considered safe. The vegetables from Kosovo are mainly safe for use in everyday diet.

Metals content of soil, leaves and wild fruit from Serbia

AbstractThe concentrations of Zn, Mn, Fe, Pb, Ni, Cu and Cd in soil, leaves and edible wild fruit (Crataegus laevigata L., Cornus mas L. and Prunus spinosa L.) from southeast Serbia were determined by atomic absorption spectroscopy. Metal translocations from soil to fruit were calculated as well as their oral intake and health risk indices. Positive correlations were found among metal concentrations in soil, leaves and fruit.

The correlation of metal content in medicinal plants and their water extracts

The quality of some medicinal plants and their water extracts from South East Serbia is determined on the basis of metal content using atomic absorption spectrometry. The two methods were used for the preparation of water extracts, to examine the impact of the preparation on the content of metals in them. Content of investigated metals in both water extracts is markedly lower then in medicinal plants, but were higher in water extract prepared by method (I), with exception of lead content. The coefficients of extraction for the observed metal can be represented in the following order: Zn > Mn > Pb > Cu > Fe. Correlation coefficients between the metal concentration in the extract and total metal content in plant material vary in the range from 0.6369 to 0.9956. This indicates need the plants to be collected and grown in the unpolluted area and to examine the metal content. The content of heavy metals in the investigated medicinal plants and their water extracts is below the maximum allowable values, so they are safe to use.

Phenolic profiles and metal ions analyses of pulp and peel of fruits and seeds of quince (Cydonia oblonga Mill.)

Six hydroxycinnamic acids were identified and determined quantitatively in methanol and acetone extracts from quince peel and pulp, namely 3-O-caffeoylquinic acid (3-CQA), 4-p-coumaroylquinic acid (HC1), 4-O-caffeoylquinic acid (4-CQA), 5-O-caffeoylquinic acid (5-CQA), derivative of p-coumaroylquinic acid (HC2) and 3,5-dicaffeoylquinic acid (3,5-diCQA). The most abundant hydroxycinnamic acid was 5-CQA (neochlorogenic acid) with 259.12-481.4mg/kgf.w. in peel and 97.33-217.36mg/kg in quince pulp. Six flavonols were determined in the extracts from quince, quercetin-3-galactoside (Q-Ga), quercetin-3-rutinoside (Q-Ru), quercetin-3-glucoside (Q-Glu), kaempferol-3-rutinoside (K-Ru), kaempferol-3-glucoside (K-Glu) and derivative of quercetin produced in the reaction between quercetin-glucoside and p-coumaric acid (Q-Glu-p-CouA). Elemental analysis of quince seeds has not been performed previously. Also, using principal component and cluster analyses, we determined a strong negative relationship between total phenols and flavonoids, and Ni and Pb, specifically higher concentrations of these compounds were associated with lower concentrations of these metals.

Chemometric Analysis of Grapes

Abstract Concentrations of several heavy metals in soil, water and grape samples (variety Plovdina) collected at five locations at different distances from the road in Southeast Serbia were determined using the Flame Atomic Absorption Spectrophotometry. There was a decrease in analyzed samples with an increase in distance from the road. A complete absence of several examined, very harmful heavy metals (Mn, Ni, and Cd) in all analyzed samples was found. The analysis of grape samples proved the presence of iron, zinc and copper in concentration ranges 3.3-19.8, 0.31-0.63, and 3.4-13.6 μg g-1, respectively. The content of heavy metals in soil, water and grapes were below allowable limits. Correlation analysis showed a significant relationship between the concentrations of metals in soil and grape samples. Graphical Abstract

The influence of the addition of polymers on the physico-chemical properties of bentonite suspensions

Bentonite clays have many applications in industries ranging from construction to cosmetics. Addition of polymers can profoundly influence the properties of bentonite suspensions and we now describe the influence of a range of different polymers. Whereas polyvinyl pyrolidone and soy isolate only slightly influenced the pH and the electrical conductivity of bentonite polymers in suspension, Carbopol solution caused decreases in both pH and electrical conductivity. As expected, strong electrolytes like sodium chloride caused big changes in the electrical conductivity of the suspensions. When the temperature of the bentonite suspensions was increased, the pH was almost unchanged, but the electrical conductivity increased. Bentonite treated with polymer suspensions can be used in purifying polluted water; for example, our results suggest that high pH caused by phosphorous salts can be addressed using bentonite modified with Carbopol.