Polyphenol Content and Antioxidant Activity of Sour Cherries From Serbia

The aim of this study was to evaluate the content of phenolics: the total phenols (TP), flavonoids (TF), anthocyanins (TA), as well as the total antioxidant\ud capacity (TAC) in three sour cherry cultivars (Prunus cerasus L.) introduced to the southeast Serbia climate conditions. Among the investigated sour cherries,\ud „Oblačinska“ cultivar contained the highest amounts of all groups of phenolics, followed by „Cigančica“ > „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 cyanidin-3-glucoside in “Marela” and “Oblačinska”, and cyanidin-3-glucosylrutinoside in „Cigančica“, 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. „Oblačinska“ 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.\u

Content of Trace Metals in Medicinal Plants and their Extracts

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 was 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

A rapid and reliable determination of doxycycline hyclate by HPLC with UV detection in pharmaceutical samples

An accurate, sensitive and reproducible high performance liquid chromatographic (HPLC) method for the quantification of doxycycline hyclate in pharmaceutical samples has been developed and validated. The drug and the standard were eluted from a Lichrosorb RP-8 (250 mm´4.6 mm, 10 mm particle size) at 20 °C with a mobile phase consisting of methanol, acetonitrile and 0.010 M aqueous solution of oxalic acid (2:3:5, v/v/v). The flow rate was 1.25 ml min-1. A UV detector set at 350 nm was used to monitor the effluent. Each analysis required no longer than 4 min. The limits of detection and quantification were 1.15 and 3.84 μg ml-1, respectively. Recoveries for different concentrations ranged from 99.58 to 101.93 %

A Multidisciplinary Approach to Teaching Metals as Part of the Elementary School Curriculum in Serbia

The multidisciplinary approach to the study of metals which we are proposing includes the modernization of the curricular content and its connection with everyday life. The use of additional teaching material in elementary schools in rural and urban areas in the wider region of the city of Niš has contributed to increased interest and activities on the part of the schoolchildren, which has in turn led to a significant quantitative improvement in their knowledge of chemistry in general, but also of metals in particular. All of the schoolchildren achieved a satisfactory level of knowledge (>50%) following the implementation of the expanded curriculum

Phenolic Content, and Antioxidant and Antimicrobial Activities of Crataegus Oxyacantha L (Rosaceae) Fruit Extract from Southeast Serbia

Purpose: The aim of this work was to determine the content of total phenols, total flavonoids, anthocyanins, as well as antioxidant and antimicrobial activities of hawthorn ( Crataegus oxyacantha L.) alcohol, hydroalcohol and aqueous extracts. Methods: The content of total phenols, flavonoids and anthocyanins of the alcohol, hydroalcohol and aqueous extracts of hawthorn were determined using spectrophotometric methods. Antioxidant assay was based on the measurement of DPPH absorbance at 517 nm caused by the reaction of DPPH with the test sample. Antimicrobial activity was evaluated by measuring the zone of inhibition against selected test microorganisms: Bacillus subtilis , Staphylococcus aureus , Escherichia coli , Pseudomonas aeruginosa , and Salmonella abony while antifungal activity was tested against two organisms: Aspergillus niger and Candida albicans . Results: The results of spectrophotometric investigations indicate that the content of total phenol compounds in the investigated extracts varied from 2.12 to 30.63 mg GAE g-1 of fresh hawthorn sample. The content of anthocyanins ranged from 0.3207 to 3.168 mg of cyanidin-3-O-glucoside g-1 of fresh hawthorn fruit. The fruit extracts showed high antioxidant activity with DPPH radical transformation value as high as 89.9 % in the methanol-water (50/50, v/v%)) extract. The ethanol extract exhibited antimicrobial activity against all test microorganisms except two, Bacillus subtilis and Staphylococcus aureus, and one species of fungi, Aspergillus niger.Flavonoid structure influenced the extract’s selectivity towards Gram-positive and Gram negative bacteria. Conclusion: Extracts of the fruit of Crataegus oxyacantha L. can be used as natural antioxidant and antimicrobial preparations

Phenolic Content, and Antioxidant and Antimicrobial Activities of Crataegus Oxyacantha L (Rosaceae) Fruit Extract from Southeast Serbia

Total phenolic and flavonoid contents of different extracts of Papaver rhoeas L. were examined. High contents of total phenolic compounds (9.73 -19.91 mg GAE/g of fresh petals) and total flavonoids (7.904 -11.45 mg QE/g of fresh petals) were determined. Red pigment present in the flowers of P. rhoeas L. originates from anthocyanins, which may act as natural antioxidants. Anthocyanins content in the investigated extracts is very unified and ranged from 4.72 to 5.193 mg of cyanidin-3-O-glukoside/g of fresh petals. The antioxidant activity of different extracts was tested using the spectrophotometric method by means of the ability of extracts to scavenge stable 1,1-Diphenyl-2-picrylhydrazyl (DPPH). All tested extracts exhibited strong scavenging activity against DPPH radicals, that is higher then 80%. Total phenolic and flavonoid contents may be related to the percentages of the scavenging activity of DPPH assay (estimated correlation coefficient are R 2 = 0.965 and 0.752, respectively). The ethanol extract of P. rhoeas L. showed antimicrobial activity against the yeast Candida albicans, and all tested bacteria except Bacillus subtilis. This paper suggests that the investigated extracts of plant P. rhoes L. could be potentially applied as an antioxidant and antimicrobial agents. Key words: Papaver rhoeas L., phenolic content, anthocyanins content, flavonoid content, antioxidant activity, antibacterial activity. INTRODUCTION Papaver rhoeas L. (Papaveraceae) is an annual herb indigenous to numerous regions in the world. In traditional medicine until synthetic drugs are developed, extracts of this plant have been used for the treatment of a wide range of diseases including inflammation, diarrhea, sleep disorders and, moreover, for cough, analgesia and also the reduction of withdrawal signs of the opioid addiction. It is also claimed that plant P. rhoeas exhibits sedative, narcotic, and emollient effects ( In the present paper, the evaluation of P. rhoeas L. from Southeast Serbia with respect to phenolic content and the antioxidant data of different extracts obtained from plant petals are reported. As it is stated earlier, numerous polyphenols are known to possess excellent antioxidant effects, especially in vitro, and the amount of total polyphenols present in a plant has been suggested to correlate with the antioxidant activity. Therefore, this work represents the first report on phenolic content and related antioxidant activity of the extracts of P. rhoeas L. from Southeast Serbia. Antimicrobial activity of ethanol extract of P. rhoeas was investigated, too. EXPERIMENTAL Plant material The plant was collected at bloom stage in few villages from the South-eastern Cape Province of Serbia in July, 2009. The plant was firstly identified by its vernacular name and later validated by voucher number of the deposited herbarium specimens at the Department of Botany (University of Novi Sad, Serbia). Preparation of plant extracts The fresh petals of P. rhoeas L. were milled by an appropriate blender. Three samples (each weighed 2.0 g) were separated from the previously homogenized plant material, and extracted with the desired volumes (30, 20 and 20 ml, respectively) of the chosen solvents (methanol, ethanol, methanol-water mixture, ethanol-water mixture and water) three times in the further course. Samples were mixed in an ultrasound bath during the extraction procedure. Such obtained extracts were filtered using the Buchner funnel and Whatman No. 1 filter paper. Solid residues were rinsed for several times in order to gain transparent extracts. Finally, the obtained plant extracts were collected in graduated flask of the same volume of 100 ml. Chemicals and reagents 1,1-Diphenyl-2-picrylhydrazyl (DPPH), quercetin and AlCl3 were purchased from Sigma Chemical Co. (St. Louis, MO, USA). FolinCiocalteu's phenol reagent and sodium carbonate were purchased from Merck Chemical Suppliers (Darmstadt, Germany). Sodium chlorate buffer (pH 1.0) and acetate buffer (pH 4.5) were purchased from the same producer. The other used chemicals including solvents were of analytical grade. Determination of the total phenolics Total phenolic contents in the extracts were determined by the modified Folin-Ciocalteu method Determination of the total monomeric anthocyanins The total monomeric anthocyanin content in the plant extracts was determined using the pH-differential method previously described by (1) Content of the monomeric antocyanin pigment (MAP) was calculated by Equation 2