Antioxidant efficiency of polyphenols from coffee and coffee substitutes-electrochemical versus spectrophotometric approach.

Antioxidant (AO) capacity of instant, espresso, filter and Turkish/Greek coffee brews, coffee substitutes (roasted chicory root, barley, pea, chickpea, carob and dried fig) and individual compounds (phenolic acids, flavonoids, methylxanthines, N-methyl pyridinium and HMW melanoidins) was assessed using DC polarographic assay based on decrease of anodic current originating from hydroxo-perhydroxo mercury complex formed in alkaline solutions of H2O2 at potential of mercury dissolution, as well as three spectrophotometric assays (DPPH, ABTS and FRAP). A large difference between applied assays ability to recognize various types of individual AOs was noticed. Only according to DC polarographic assay significant AO activity was ascribed to methylxanthines and N-methyl pyridinum. The total content of phenolics (TPC) present in complex samples was determined by FC assay. The highest TPC was ascribed to instant coffees and coffee substitutes while the lowest to decaffeinated filter coffee. Complex samples were grouped based on principal components analysis, phenolics AO coefficient, calculated as the ratio between AO capacity and TPC, and relative AO capacity index (RACI), calculated by assigning equal weight to all applied assays including FC. The highest values of RACI were ascribed to instant coffee brews, followed by substitutes while the lowest to the decaffeinated espresso coffee.

Chemical composition, antiproliferative and antioxidant activity of differently processed Ganoderma lucidum ethanol extracts.

The content of phenolic compounds (TPC) and glucans, as well as the effectiveness of antiproliferative and antioxidant activity of differently processed Ganoderma lucidum ethanol extracts were determined and compared. The content of glucans (total, α- and ß-) strongly depended on the extraction time and particle size, but only interaction of these parameters influenced the TPC. Gallic acid, quercetin, trans-cinnamic acid, kaempferol, hesperetin and naringenin were detected in extracts by HPLC-DAD. The most abundant phenols were hesperetin (1.875-3.222 µg/g) and naringenin (1.235-2.856 µg/g). The ethanol extracts exhibited noteworthy antioxidant activity, but the significant amount of phenolic compounds was strongly linked to polysaccharides, and hence reduced their antioxidant capacity. The results of the antiproliferative activity in vitro showed that the analyzed extracts were the most effective against HeLa cells. Significant correlations were observed between the antiproliferative effect and the TPC/glucan content of extracts.

Antioxidant Capacity Determination of Complex Samples and Individual Phenolics - Multilateral Approach.

Antioxidant (AO) capacity of various medicinal plants extracts and phenolic compounds was assessed by the most widely used spectrophotometric assays such as ferric reducing antioxidant power (FRAP) and scavenging of 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH). In addition, two direct current (DC) polarographic assays, one based on a decrease of anodic current of [Hg(O2H)(OH)] - HydroxoPerhydroxoMercury(II) Complex (HPMC) formation in alkaline solution of H2O2, at the potential of mercury dissolution and another recently developed Mercury Reduction Antioxidant Power (MRAP), based on a a decrease of cathodic current of Hg(II) reduction were employed. Percentage of both currents decrease was plotted versus the volume of gradually added complex samples or the amount of individual ones and the slopes of these plots were used to express AO capacity. Total phenolic content (TPC) of extracts was determined by Folin- Ciocalteu (FC) assay. Correlations between applied assays were calculated by regression analysis. Relative Antioxidant Capacity Index (RACI), calculated by assigning equal weight to all applied assays and Phenolic Antioxidant Coefficients (PAC), calculated as a ratio between particular AO capacity and TPC, were used to achieve more comprehensive comparison between analyzed samples, as well as applied assays.

Physicochemical, antioxidant and sensory properties of peach wine made from redhaven cultivar.

Physicochemical, sensory, and health-related characteristics of peach wine produced from Redhaven variety and selected white wines produced from various grape varieties were determined and compared. The alcohol content, titratable acidity, and total extract of peach wine was significantly lower compared with that of white wines, while its pH value was higher. The content of total phenolics (TPC) and flavonoids (TFC) of peach wine (402.53 mg/L GAE and 332.67 mg CAE/L, respectively) have been found significantly higher in comparison with that of white wines (TPC range 243.67-319.00 mg/L GAE, TFC range 129.67-175.17 mg CAE/L). The main phenolic compounds found in peach wine were chlorogenic acid, caffeic acid, and catechin (3.59, 0.87, and 0.60 mg/L, respectively). Antioxidant capacities were strongly correlated with total phenolics with correlation coefficients over 0.99. The highest antioxidant capacity was ascribed to peach wine. The results of sensory analysis indicated that the peach wine was very well accepted by the regular consumers of wine and can be a very interesting product in the market.