The aim of this research was to determine the total phenolic and flavonoid contents as well as to measure antioxidant activity of 24 different commercial beers consumed in Serbia.The major phenolic acids (gallic acid, protocatechuic acid, 4-hydroxybenzoic acid, 2,5- dihydroxybenzoic acid, vanillic acid, caffeic acid, syringic acid, p-coumaric acid, ferulic acid, sinapic acid, salicylic), (+)-catechin, and (-)-epicatechin were also determined by high pressure liquid chromatography method using a photodiode array detector. Gallic acid, ferulic acid, and protocatechuic acid are the most abundant phenolic acids in all samples, followed by (+)-catechin. The total phenolic content was determined using the Folin-Ciocalteu assay. The total flavonoids were measured using spectrophotometrics as the aluminum chloride assay. The results showed that the highest total phenolic and flavonoid contents were established in dark and light beer samples. 2,2-Diphenyl-1-picrylhidrazyl radical scavenging activity, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) radical cation scavenging activity, and ferric reducing/antioxidant power were used to assess the antioxidant potential of beers. These assays, based on different chemical mechanisms, were selected to take into account the wide variety and range of action of antioxidant compounds present in selectedbeer samples. All beers showed antioxidant power, but a wide range of antioxidant capacities was observed. Statistical differences between ferric reducing-antioxidant power and the other two antioxidant capacity assays were confirmed. This study will be useful for the appraisal of phenolic profile and antioxidant activities of various beers, and it will also be of interest for people who like drinking this beverage.

Blackthorn (Prunus spinosa L.) is commonly used in food industry and phytotherapy. The contents of phenols, flavonoids, anthocyanins and antioxidative activity in extracts of blackthorn fruit were determined using spectrophotometric methods. The content of total phenol compounds varies from 15.33 to 20.94 mg GAE g -1 of fresh fruit. The content of total flavonoids is very low and ranges from 0.419 to 1.31 mg QE g -1 of fresh fruits. Anthocyanins content lies between 0.112 mg cyanidin 3-glucoside/g of fresh sample in ethanol extract and 0.265 mg of cyanidin 3-glucoside g -1 of fresh blackthorn fruit in methanolwater 50/50 (V/V) extract. The differences in total phenol compounds content depend on used extraction medium as a consequence of different polarity of used organic solvents and their mixtures, which selectively extract individual compounds. All explored extracts exhibited strong scavenging activity against DPPH radicals, which ranges from 32.05 to 89.10%. Phenolic acids (neochlorogenic and caffeic acids), flavonoids (quercetin and myricetin) and anthocyanins (cyanidin-3-O-glucoside, cyanidin-3-O-rutinoside and peonidin-3--O-glucoside) were identified in investigated ethanol extracts by HPLC analysis. Ethanol extract shows significant antimicrobial activity against Staphylococcus aureus ATCC 6538, Escherichia coli ATCC 8739, Pseudomonas aeruginosa ATCC 9027 and Salmonella abony NCTC 6017 and antifungal activity against Candida albicans ATCC 10231. Blackthorn fruit extract exhibits a high phenolic content and a high antioxidant activity, and can be used as an antioxidant in food and pharmaceutical industries.

No abstract

The heavy metals (Fe, Cu, Zn and Mn) contents of selected plant species, grown in Southeast region of Serbia, that are traditionally used in alternative medicine were determined. Among the considered metals, iron content was the highest one and varied from 137.53 up to 423.32 mg/kg, while the contents of Cu, Zn and Mn were remarkably lower, and ranged from 8.91 to 62.20 mg/kg. In addition, an analysis of plants extracts showed a significant transfer of heavy metals during extraction procedure; therefore, the corresponding extraction coefficients reached values up to 88.8%. Those were especially high in the ethanol based extracts. Moreover, it is established that such coefficients mostly depend on the solvent nature and also on the treated plant species. The obtained results impose that medicinal plants from Southeast region of Serbia due to rather low content of heavy metals are appropriate for preparation of teas and medicinal extracts

Fruits and vegetables constitute the cheapest source of essential trace elements for the majority of people living in developing countries. The Cu, Fe and Zn contents in twenty selected wine samples produced in the South-East region of Serbia were determined by flame atomic absorption spectrometry. The Cu concentrations varied from 0.07 to 0.57 ppm in wines, and the Fe concentrations fluctuated from 2.93 to 36.2 ppm, while the Zn levels were in the range from 0.21 to 0.67 ppm. The established contents of Cu and Zn showed that wines from this part of the world could serve as good dietary sources of the essential trace metals, and the determined values were within the allowed metals levels in wines for human consumption.

Based on the detected content of analysed elements it can be concluded that nuts may be a good additional source of minerals as micronutrients.

No abstract

The aim of this work was to determine the content of 22 macro- and microelements in ten raw Serbian propolis samples which differ in geographical and botanical origin as well as in polluted agent contents by atomic emission spectrometry with inductively coupled plasma (ICP-OES). The macroelements were more common and present Ca content was the highest while Na content the lowest. Among the studied essential trace elements Fe was the most common element. The levels of toxic elements (Pb, Cd, As and Hg) were also analyzed, since they were possible environmental contaminants that could be transferred into propolis products for human consumption. As and Hg were not detected in any of the analyzed samples but a high level of Pb (2.0-9.7 mg/kg) was detected and only selected portions of raw propolis could be used to produce natural medicines and dietary supplements for humans. Obtained results were statistically analyzed, and the examined samples showed a wide range of element content.