HPLC Analysis of Phenolic Compounds and Antioxidant Activity of Ribes Fruit Leaves

Berry fruit leaves are recognized as potential medicaments which are rich in different phenolic compounds, and have been used in folk medicine for centuries. In order to evaluate phenol composition of fruit leaves from red currant (Ribes rubrum) and black currant (Ribes nigrum) species were subjected to the spectrophotometric and HPLC analysis. The antioxidant activity was estimated using DPPH free radical scavenging assay. Flavonols, flavan-3-ols and phenolic acids were the main phenol classes found in the investigated leaf extracts. Investigated extracts showed significant antioxidant activity and a correlation with total phenol content. Ribes leaf extracts, rich in phenolic content, with significant antioxidant activity, can be used as medical supplements

Kinetic Study of Oxidation Degradation of Polyphenols in Sour Cherry and Blackberry Extracts During Storage

In this study was to investigate the influence of storage time, light and temperature on stability of polyphenols in sour cherry (Prunus cerasus) and blackberry (Rubus fruticosus), were harvested in western Serbia (Rasinski region). Total phenol content was monitored in the fruit extracts during 23 days stored at 7°C under darkness and 90 days storage at 23°C in oxygen. For analyzed extracts, first-order reaction kinetics was established for the degradation process of polyphenols. The temperature dependence of the polyphenols degradation rate constants was expressed by the temperature coefficients Q10 of the process. It is found that the Q10 values of polyphenols degradation in sour cherry and blackberry extracts were 1.247 and 3.239, respectively

Polyphenols and Antioxidant Activity of Different Vinegrape Leaves

The volume of the grape waste produced directly relates to the volume of grapes pressed and in turn depends on the specific climatic conditions of the relevant vintage. The aim of this work is to evaluate vinegrape leaves as a potential source of natural antioxidants – polyphenols for their possible use as dietary supplement or food antioxidants. To this purpose antioxidant activity and contents of phenolic compounds of the leaves extracts of five grape varieties of Vitis vinifera L (Vranac, Prokupac, Merlot, Gamay and Italian Rizling), grown in southern Serbia were investigated. The analysis show high content of polyphenols reflecting their high antioxidant activity (R2 = 0.9819, p<0.01). According to the obtained results, the leaves extracts, can be considered rich natural source of phenolic compounds with good antioxidant properties

Phenolic compounds and biological activity of Capsicum annuum L.

The objective of this study was to evaluate antifungal and antioxidant activities of vegetable extracts (Capsicum annuum L. cv. Dora, cv. Strizanka, cv. Morava), grown in Serbia. Different experimental models have included the determination content of total phenolics, total flavonoids, antioxidant capacity and minimum inhibitory concentration of the extract. The phenolic composition of different extracts was determined by the high-performance liquid chromatography (HPLC) method. The highest amounts of phenols and highest antioxidant capacity were found in the cultivar Dora extracts. The highest phenolic content has been shown in cultivar Strizanka ethanol extract. All of the extracts showed strong antimicrobial activity. On the basis of the results obtained, the extracts were found to serve as a potential source of natural antioxidants and antimicrobial due to their marked activity. The obtained results may be useful in the evaluation of new dietary and food products.Key words: High-performance liquid chromatography (HPLC), phenolic components, antimicrobial activity, antioxidant activity

QUALITY AND ANTIOXIDANT PROPERTIES OF PINOT NOIR GRAPEVINE VARIETY UNDER AGROECOLOGICAL CONDITIONS OF VRŠAC IN SERBIA

This research was focused on the antioxidant properties of grape variety Pinot Noir in the period from 2009-2011 in Vojvodina (location Vršac - 45o 8' 40,80" N; 21º 24' 7,97" E, 199 m a. s. l.). Pinot Noir variety was grown on Berlandieri x Riparia Kober 5BB rootstock, at a distance of 3 x 0.8 m. Mechanical properties of bunch and berry, quality and chemical properties of grapes were analyzed. The contents of monomeric and polymeric anthocyanins in grape berry skin were 11.68 and 94.67 mg of malvidin-3-glucoside/g. Correlative relationship between phenolic content and antioxidant activity of berry skin was r = 0.754, n = 18, p &lt;0.0005. Quality and antioxidant activity of Pinot Noir grape variety was determined to be high under the agroecological conditions of Vršac in Serbia

Development of an ultrasonic method for effective extraction of capsaicin as a potent bioactive compound

Many recent studies concerning the medicinal use of capsaicin as a bioactive compound, justify the demands for new and effective methods of its extraction. Its pharmacological activity includes antihyperlipidemic, antiglicemic, anti-oxidative, antitumor properties. The majority of basic research studies suggest that capsaicin induces cell-cycle arrest or apoptosis or inhibits proliferation in different malignant cells including lung cancer, adeno carcinoma, pancreatic cancer, breast cancer. In many cases this activity of capsaicin is concentration dependent and that is one of the reasons for establishing a method for more effective extraction of capsaicin from hot peppers. Moreover synergistic effect of capsaicin with the effects of the other bioactive compounds of the peppers (vitamin C, vitamin E, quercetin, luteolin, carotene), makes these extracts more effective in potential antitumor therapy. This method for capsaicin extraction was performed by using an ultrasonic bath with frequency of 35 kHz. We have used three different ratios of solid/liquid phase, different extraction times (20 to 60 min), and different temperatures (45 to 60°C). Concentration of capsaicin in the extracts was measured by HPLC-DAD. Results obtained from liquid chromatography showed that capsaicin concentration was highest in the extract obtained with 1:25 (solid/liquid ratio), with ethanol (96% V/V). Results for time and temperature dependency on the efficiency of extraction of capsaicin showed that concentration of capsaicin in extracts from 50 and 60°C, is 0.406 mg/ml and 0.726 mg/ml, successively, and for the time of 60 minutes the highest concentration of capsaicin was obtained 0.685 mg/ml. As a conclusion of this study we can propose that extraction time of 60 min on temperature of 60°C for 1/25 (solid/liquid ratio), gives the most efficient extraction of capsaicin. Optimization of the conditions for ultrasonic method of extraction is one of the key factors for obtaining an extract with high concentration of capsaicin, and protected pharmacological activity

Antimicrobial activity of some isatin-3-thiosemicarbazone complexes

Isatin-3-thiosemicarbazone complexes with Co(II), Ni(II), Cu(II), Zn(II), Hg(II) and Pd(II) were synthesized and evaluated for their antimicrobial activity against 7 pathogenic bacteria and 4 fungi. The complexes have an enhanced activity compared to the ligand due to transition metal involved in coordination. The anti-amoebic activity in vitro was evaluated against the HM1:IMSS strain of Entamoeba histolytica and the results were compared with the standard drug, metronidazole. The preliminary test results showed that the complexes had better anti-amoebic activity than their respective ligands. Moreover, the complexes showed better inhibition of the test organism

Thermal behaviour of Co(II), Ni(II), Cu(II), Zn(II), Hg(II) and Pd(II) complexes with isatin-beta-thiosemicarbazone

The isatin-beta-thiosemicarbazone (ITC) complexes of Co(II), Ni(II), Cu(II), Zn(II), Hg(II) and Pd(II) were prepared and characterized by elemental analysis, as well as molar conductivity, magnetic susceptibility, FTIR, UV-Vis and H-1 NMR spectroscopic methods. The complexes were also studied for its thermal stability. They all behaviour as anhydrous complexes and its thermolysis passes through the stages of deamination (517-547 K) and complete thermal decomposition (619-735 K).32nd Workshop on Heterogeneous Equilibria between Phases (JEEP 2006), Mar 30-31, 2006, Univ Rouen, Rouen, Franc

Spectrophotometric study of Co(II), Ni(II), Cu(II), Zn(II), Pd(II) and Hg(II) complexes with isatin- β-thiosemicarbazone

The composition and stability of the complexes of isatin-b-thiosemicarba­zone with Co(II), Ni(II), Cu(II), Zn(II), Pd(II) and Hg(II) have been investigated us­ing spectrophotometric method at 30 °C and constant ionic strength of 0.1 mol dm-3 (KNO3) in 70 % ethanol. Experimental results indicate the formation of MeL and MeL2 complexes for Ni(II) and Co(II), and MeL for Cu(II), Zn(II), Pd(II) and Hg(II) complexes, whose stability constants, bn, have been calculated using a com­puteri­zed iterative method of successive approximation