Multielement analysis and antioxidant capacity of Merlot wine clones developed in Montenegro.

The overall aim of this paper was to compare the multielement composition and antioxidant capacity of two Montenegrin Merlot wines obtained from specific vine clones (VCR1 and VCR 101) along with commercial Merlot wine throughout the consecutive vintages in 2010 and 2011. Elemental composition was analysed using inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS). Additionally, antioxidant capacity was assessed by cyclic voltammetry. VCR 1 wine from 2011 stood out for its elemental composition. On the other hand, antioxidant capacity of VCR 101 wines was the highest one for the both vintages. According to the experimental data obtained, all three wines are good source of essential elements and products with a significant antioxidant activity and specific geographical origin.

Comparative analytical study of the selected wine varieties grown in Montenegro.

Samples of the selected red wine varieties grown in Montenegro (Merlot, Cabernet Sauvignon and Vranac; vintages 2010-2012) were compared according to total phenolic content, anti-DPPH radical activity, phenolic profile and elemental composition. All the samples showed profound anti-DPPH radical activity, due to high content of total phenolic compounds (R = 0.92). The most abundant phenolics were catechin and gallic acid with the highest values recorded for Merlot 2012 (43.22 and 28.65 mg/L, respectively). In addition to this, the content of essential elements including the potentially toxic ones was within healthy (safe) level for all the samples analysed. This study has actually pointed out Merlot wine variety as the best quality one, though all three varieties may be used as safe and health-promoting nutritional products.

Optimisation of isolation procedure for pyrrolizidine alkaloids from Rindera umbellata Bunge.

Procedure for isolation of pyrrolizidine alkaloids (PAs) from Rindera umbellata Bunge plant species was optimised. Different extraction media (methanol, ethanol and sulphuric acid), concentration and volume of sulphuric acid, pH of PA solution for alkaline extraction, extraction time and techniques (maceration, ultrasonic and overhead rotary mixer assisted extraction) were investigated. The yields of six PAs (7-angeloyl heliotridane, 7-angeloyl heliotridine, lindelofine, 7-angeloyl rinderine, punctanecine and heliosupine) were monitored by GC-MS/FID. The best results for the isolation all of six PAs were obtained when the extraction was performed with 1 M sulphuric acid (30 mL per 1.00 g of dried sample) by overhead rotary mixer during three days. Optimal pH value for alkaline extraction of PAs with CH2Cl2 was 9, and the extraction should be performed with four portions of 30 mL of CH2Cl2. This procedure could be also useful for a plant sample preparation for GC and LC analyses of PAs.

Pyrrolizidine alkaloids and fatty acids from the endemic plant species Rindera umbellata and the effect of lindelofine-N-oxide on tubulin polymerization.

The examination of the aerial parts, roots, and seeds of the endemic plant Rindera umbellata is reported in this paper for the first time. Phytochemical investigation of R. umbellata led to the isolation and characterization of ten pyrrolizidine alkaloids and eleven fatty acids in the form of triglycerides. Pyrrolizidine alkaloids 1-9 were found in the aerial parts, 7 and 8 in the roots, and 6-10, together with eleven fatty acids, in the seeds of this plant species. The structures of compounds 1-10 were established based on spectroscopic studies (¹H- and ¹³C-NMR, 2D NMR, IR and CI-MS). After trans-esterification, methyl esters of the fatty acids were analyzed using GC-MS. The effect of lindelofine-N-oxide (7) on tubulin polymerization was determined.

Antioxidant activity of propolis extracts from Serbia: a polarographic approach.

Antioxidant activity (AO) of commercial propolis extracts (PEs), available on Serbian market, was determined by direct current (DC) polarography. Polarographic anodic current of 5.0 mmol L(-1) alkaline solution of H2O2 was recorded at potentials of mercury dissolution. Decrease of the current was plotted against the volume of gradually added PEs. The volume of PE causing 20% current decrease was determined from the linear part of the plot. Antioxidant activity was expressed in H2O2 equivalent (HPEq), representing the volume of PE that corresponds to 1.0 mmol L(-1) H2O2 decrease. Resulting HPEq ranged between 1.71±0.11 and 8.00±0.18 µL. Range of 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging activity was from 0.093±0.004% to 0.346±0.006%. Total phenolic content (TCP) of PE with superior AO activity was 5.31±0.05% g GAE, while the extract with the lowest activity contained 1.45±0.02% g GAE. Antioxidant activity, determined by polarographic method, was correlated with DPPH scavenging activity (R2=0.991) and TCP (R2=0.985). Validity of obtained results was further confirmed using ANOVA and post hoc Tukey HSD test.

Changes of hydrogen peroxide and radical-scavenging activity of raspberry during osmotic, convective, and freeze-drying.

This study was conducted to investigate the influence of different drying treatments on antioxidant (AO) activity and phenolic content of raspberry (Rubus idaeus), cultivar Willamette. Whole raspberry fruits were dried convectively (air-drying), osmotically, and freeze-dried. Acetone-water extracts of fresh and dried raspberries were assessed for total phenolic content by standard Folin-Ciocalteau method. Two AO assays were applied, a recently developed direct current (DC) polarographic assay based on decrease of anodic oxidation current of hydrogen peroxide and widely used radical scavenge against the 1,1-diphenyl-2-picrylhydrazyl (DPPH). Strong correlation has been obtained between both AO assays and total phenolic content. In addition, some individual phenolic compounds present in raspberry have been assessed using DPPH and DC polarographic assay. Comparison and evaluation of drying methods has been based on preservation of AO activity and total phenolic content. Obtained results confirmed superiority of freeze-drying; convective drying caused slight changes while osmotic dehydration showed a significant decrease of phenolic compounds and AO activity.

Polarographic assay based on hydrogen peroxide scavenging in determination of antioxidant activity of strong alcohol beverages.

Total antioxidant (AO) activity of strong alcohol beverages such as wine and plum brandies, whiskeys, herbal and sweet fruit liqueurs have been assessed using a polarographic assay based on hydrogen peroxide scavenging (HPS). Rank of order of total AO activity, expressed as percentage of decrease of anodic oxidation current of hydrogen peroxide, was found analogous with total phenolic content estimated by Folin-Ciocalteau (FC) assay and radical scavenging capacity against the stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH). Application of the assay for surveying of a quarter century long maturation of plum brandy in oak barrel was demonstrated. In addition, influence of different storage conditions on preservation of AO activity of some herbal liqueurs was surveyed. Wide area of application of this simple, fast, low cost and reliable assay in analysis and quality monitoring of various strong alcohol beverages was confirmed.

Antioxidant activity of wines determined by a polarographic assay based on hydrogen peroxide scavenge.

Antioxidant (AO) activity of various red and white wines of different origin as well as some individual phenolic compounds present in wine has been assessed using a polarographic assay. Direct current polarography has been used to survey hydrogen peroxide scavenge (HPS) upon gradual addition of tested samples. Results expressed as reciprocal value of wine volume required for 50% decrease of anodic limiting current of hydrogen peroxide have been validated through correlation with Folin-Ciocalteau and DPPH assays. All wines exhibit HPS activity analogous with total phenolic content and DPPH scavenge. Reliability and accuracy, low cost, and rapid and direct experimental procedure open a wide area for application of this assay, making it a good alternative to standard, widely accepted AO assays.

Application of a novel antioxidative assay in beer analysis and brewing process monitoring.

A novel antioxidative assay based on direct current polarography has been developed. Quantification of antioxidative (AO) activity has been based on a decrease of hydrogen peroxide anodic current in the presence of antioxidants. An efficient experimental procedure, without any special pretreatment of analyzed samples, has been applied. Antioxidative activity of different kinds of commercial beers (dark, blond, and alcohol-free), some small-scale made special beers with medicinal herbs and mushroom extracts, extracts themselves, as well as individual phenolic components present in beer has been measured. In addition, changes of AO activity during the full-scale industrial process of beer production have been monitored. A strong correlation between results obtained and total phenolics content has been observed. The assay can be recommended for application in brewing industry, either to survey a process with the aim to optimize relevant technological factors or to analyze quality of final product.