Two fraction, one containing flavonols, flavan-3-ols, phenolic acids and the other containing anthocyanins, were isolated from Rubus (red raspberry, blackberry) and Prunus (sweet cherry, sour cherry) fruits to study their phenol content by HPLC and antioxidant activity using the DPPH test. Raspberries and blackberries were characterised by catechins and ellagic acid derivatives; sour and sweet cherries by phenolic acids. All fruits had relatively high anthocyanin content. Anthocyanins contributed more to the antioxidant activity of all fruits (90%) than flavonols, flavan-3-ols and phenolic acids (10%). A biphasic reaction was observed between DPPH • radicals and phenols, with 'fast' and 'slow' scavenging rates which might be important in the biological activity of these fruits. Sour cherries and blackberries which stand out with the highest total phenol content (1416 and 1040 mg kg )1 ) had also the strongest antioxidant activity (EC 50 = 807 and 672 g of fruit per gram of DPPH) and can be considered as good source of dietary phenols.

Carbon nanofibres (CNFs) and graphite flake microparticles were added to thermoplastic polystyrene polymer with the aim of making new conductive blends suitable for 3D‐printing. Various polymer/carbon blends were evaluated for suitability as printable, electroactive material. An electrically conducting polystyrene composite was developed and used with commercially available polystyrene (HIPS) to manufacture electrodes suitable for electrochemical experiments. Electrodes were produced and evaluated for cyclic voltammetry of aqueous 1,1’‐ferrocenedimethanol and differential pulse voltammetry detection of aqueous Pb2+ via anodic stripping. A polystyrene/CNF/graphite (80/10/10 wt%) composite provides good conductivity and a stable electrochemical interface with well‐defined active geometric surface area. The printed electrodes form a stable interface to the polystyrene shell, give good signal to background voltammetric responses, and are reusable after polishing.

Carnosine is a dipeptide synthesized in the body from β-alanine and L-histidine. It is found in high concentrations in the brain, muscle, and gastrointestinal tissues of humans and is present in all vertebrates. Carnosine has a number of beneficial antioxidant properties. For example, carnosine scavenges reactive oxygen species (ROS) as well as alpha-beta unsaturated aldehydes created by peroxidation of fatty acid cell membranes during oxidative stress. Carnosine can oppose glycation, and it can chelate divalent metal ions. Carnosine alleviates diabetic nephropathy by protecting podocyte and mesangial cells, and can slow down aging. Its component, the amino acid beta-alanine, is particularly interesting as a dietary supplement for athletes because it increases muscle carnosine, and improves effectiveness of exercise and stimulation and contraction in muscles. Carnosine is widely used among athletes in the form of supplements, but rarely in the population of cardiovascular or diabetic patients. Much less is known, if any, about its potential use in enriched food. In the present review, we aimed to provide recent knowledge on carnosine properties and distribution, its metabolism (synthesis and degradation), and analytical methods for carnosine determination, since one of the difficulties is the measurement of carnosine concentration in human samples. Furthermore, the potential mechanisms of carnosine’s biological effects in musculature, metabolism and on immunomodulation are discussed. Finally, this review provides a section on carnosine supplementation in the form of functional food and potential health benefits and up to the present, neglected clinical use of carnosine.

The mechanism of electrochemical oxidation of rutin on a glassy carbon electrode was studied at different pH by using several electrochemical techniques (cyclic, linear sweep, differential pulse and square-wave voltammetry) in order to give deeper insight into the mechanism of electrochemical oxidation of rutin and adsorption of its oxidation products on a glassy carbon electrode. It was determined that the rutin oxidation process on a glassy carbon electrode is reversible, pH dependent and includes the transfer of 2 e– and 2 H+. The products of electrochemical oxidation strongly adsorb on the electrode surface. Maximum surface coverage, Γmax, decreased with increasing scan rate from 3.4 × 10–9 mol cm–2 at scan rate 20 mV s–1 to 1.5 × 10–9 mol cm–2 at scan rate 100 mV s–1 and adsorption equilibrium constant was log K = 4.57 ± 0.05. Antioxidant properties of rutin were investigated by a Trolox equivalent antioxidant capacity (TEAC) assay. It was found that the TEAC values of rutin depend on concentration and the EC50 value of rutin amounted 0.23.

This work combines laboratory quantitative analysis of colored solutions and common devices for digital imaging (digital or web cameras or mobile phones, i.e., smartphones). ColorX software, specially designed for this study, was used for data collection and analysis in order to calculate concentrations of colored solutions from measured RGB values. Three different custom methods for determination of concentration have been developed: (i) RGB value measurement by pixel, (ii) RGB value measurement by pixel and Gaussian blur, and (iii) calculation of average RGB value of the selected image area. The performance of the developed software, ColorX, is demonstrated using different colored solutions, KMnO 4 (purple), CoSO 4 (red), NiSO 4 (green), and CuSO 4 (blue) solutions, as well as the Lowry protein assay (blue) in terms of its determination of the concentrations of unknown samples. The most suitable and effective method for studying the mentioned solutions was the calculation of an average RGB value for a selected image area. ColorX software is primarily designed for accessibility and simplicity, with the aim of promoting and encouraging students to explore and discover potential applications for digital imaging technology in basic analytical chemistry concepts.