Bronislaw Glod

Free radicals are atoms, compounds or ions with the odd numbers of electrons. They are usually more reactive than other chemical species and harmful to biological cells and the whole living organisms, like human beings. They are implicated in the pathogenesis of many diseases including, e.g., cancer, Alzheimer’s disease, rheumatoid arthritis, and Parkinson’s disease. Free radicals are inactivated by the free radicals scavengers and/or antioxidants. Sometimes, both terms are used convertib le. Usually, the antioxidants are also identified with the sample antiradical activity because free radicals or, more generally, reactive oxidant species (ROS) are main oxidants occurred in the biological samples. Total antioxidant potential (TAP) is proportional to the products of concentrations of all antioxidants in the sample and their antioxidant powers (rate constants). Due to components interaction in the sample, tap frequently better describes the antioxidant properties of the complex b iological samples, such as herbal extracts. The aim of the study was to determine the total antioxidant potential of water infusions of selected medicinal plants. In order to investigate the TAP we used spectrophotometric and chromatographic methods. The results were correlated with the TAPs values related to the DPPH and peroxyl radicals as well as to the total polyphenols content in the sample.

The determination of free radicals and their reaction products in biological systems is discussed, with an emphasis on the use of liquid chromatographic methods for the analysis. Free radicals formed from oxygen and its reduction products, nitric oxide, and lipid radicals are considered. Whilst reversed-phase high-performance liquid chromatography has found wide application for these analyses, ion-exclusion chromatography also has significant potential and some developments in this area are described.

Kompleksy metali z zasadami Schiffa znane s od ko ca XIX wieku. Zwi zki te wzbudzaj zainteresowanie ze wzgl du na obecno ugrupowania iminowego RCH=NR’ w chemii koordynacyjnej oraz w badaniach procesów metabolicznych zachodz cych w organizmach ywych. Zasady Schiffa tworz z metalami grup przejciowych kompleksy o ró nej strukturze, stabilizuj c ró ne stopnie utleniania tych e metali. W pracy przedyskutowano rozdzia kompleksów niklu (II) z pi cioma ligandami, zasadami Schiffa. Zosta y one rozdzielone w uk adzie faz odwróconych. Z danych literaturowych wiadomo, e zarówno jon centralny jak i ligandy badanych kompleksów ulegaj reakcj utleniania i redukcji. Okaza o si jednak e, e w niektórych przypadkach detektor elektrochemiczny charakteryzowa si du niepewno ci pomiaru i/lub ma czu o ci . Elektrochemiczne w asno ci kompleksów zbadano za pomoc woltamperometrii cyklicznej. Okaza o si , e niektóre z nich adsorbowa y si na elektrodzie i/lub tworzy y przewodz ce polimery na powierzchni elektrody, w rozpuszczalnikach o niskiej liczbie donorowej.

Abstract Cyclodextrins (CDs) are a group of toroidal oligosaccharides that contribute to several guest-associated phenomena in gas or liquid phases. For over 100 years these macrocycles have been of interest in both pure research as well as applied technologies. The host–guest nanocapsulation of low-molecular-mass compounds with cyclodextrins (host and guest molecules, respectively) is highly molecular shape selective and in modern analytical chemistry is the method of choice for resolution of various isomers, including enantiomers. Particularly, in separation systems involving liquid mobile phases, cyclodextrins are frequently used as very efficient chiral and nonchiral selectors. CD modification of stationary phase allows enantiomers separation by gas chromatographic techniques. Over the past few decades these compounds have found a wide range of applications, in pharmacy, cosmetology, analytical, and food chemistry. The polar/nonpolar nature of cyclodextrins results in that compounds capsulated within CD cavity are characterized by different physicochemical properties than the free ones. CDs are commonly used to (1) increase the solubility of included compounds; (2) stabilize oxygen sensitive substances; (3) stabilize highly volatile compounds, enabling easy storage or transport; (4) dispose of toxins; (5) modify the chemical reactivity of the included substance and change its physicochemical and/or biomedical properties (mask of color, unpleasant odor or taste); as well as (6) reduce the adverse effects of drugs. Inclusion phenomena can be studied using UV-Vis, IR, NMR, cyclic or differential pulse voltammetry. In cosmetology CDs are used to change the volatility of the target substances, particularly for maintaining longer aroma of the commercial products, removing unwanted odors, or releasing the active substances to the nails or skin. Practical applications in agriculture and environment include the delay of germination in seeds/potatoes and removing of heavy metals and organic micropollutants. By complexation of nonpolar molecules, CDs increase bioavailability of pharmaceutical formulations, especially drugs that are nonsoluble in pure water steroids. In the food industry cyclodextrins are used as stabilizers for butter, margarine, mayonnaise, or garlic dry extracts. This chapter summarizes the literature concerning general information about cyclodextrins and related macrocycles, their supramolecular nano-complexes with low-molecular mass compounds, physicochemical properties of host–guest complexes, encapsulation of bioactive target components in food and cosmetics products as well as pharmaceutical formulations, based on the research communications, mainly published over a period of the last 3 years (2012–15). Moreover, the research dealing with the influence of encapsulated target compounds by CDs on their antioxidant properties is discussed. Some aspects of antioxidants analysis and preservation of such chemicals in complex samples in the presence of macrocyclic additives as well as quantitative analysis of free radicals and radicals scavengers is presented from a practical point of view. In addition, a review concerning the use of macrocyclic nano-additives as an ingredient of food, pharmaceutical formulations, cosmetics, and related products that are considered theoretically as well as currently on the market is reported.

There is limited literature on the antioxidative properties of food of animal origin. Measurements of antioxidative properties are usually performed using the reaction of reduction of colored 2,2-diphenyl-1-picrylhydrazyl (DPPH) radials. Changes of the DPPH color are tracked photometrically. These measurements are interfered by both, the tested samples and reduced DPPH. This study aims to demonstrate the ability to separate different forms of DPPH (DPPH• and DPPH-H) by thin-layer chromatography (TLC). Further, it has been practically applied in the study of the determination of antioxidative properties of the meat samples. It was found that TLC can be used for the separation of different forms of DPPH as well as for measurement of TAP (total antioxidant potential) values related to the DPPH•. The strongest antioxidant properties were observed for pork neck extracted in buffer pH 2 and for smoked salmon fish extracted in acetone, the lowest for veal and turkey fillet extracted in met...

The antioxidative activities of honeys collected in Poland were screened. The total antioxidant potential (TAP) provides more information about the system than the determination of individual antioxidant. TAP is proportional to the sum of products of concentrations of all antioxidants in the sample and their antioxidant powers (rate constants). To measure, compare and correlate TAPs, we used techniques which we had recently elaborated (i) related to hydroxyl radicals, (ii) RP-HPLC measurements with amperometric detection and (iii) differential pulsed voltammetry (DPV). They were correlated with techniques already described in the literature (i) related to the DPPH radicals, (ii) the total content of phenolic compounds and (iii) color intensity. All assays revealed the following order of obtained TAP values: buckwheat > honeydew > linden > multi-flower> acacia honey. Correlations were found between results obtained using different techniques. There was also a significant ...

The aim of this preliminary study was to investigate whether the fermentation process affects the antioxidative properties of honeys. Therefore, the total antioxidant potential (TAP) of eleven meads was examined. TAPs were estimated using DPPH, hydroxyl radicals, and amperometric measurements in the flow-through HPLC system. The results were correlated with the total content of polyphenols and anthocyanins. Additionally, the concentrations of ethanol, sugars, and hydrogen peroxide were measured. The influence of side reactions and the presence of hydrogen peroxide, glucose, ethanol, and anthocyanins on the free radicals generation were also tested. The use of HPLC electrochemical detection for TAP measurements is particularly preferred. Depending on the potential used, different antioxidants can be measured. It turned out that fruit and species meads are characterized by much higher TAPs measured at high potential of the working electrode than at lower potential due to the high conc...

In this paper a new method for the determination of Total Antioxidant Potential (TAP) using mass spectrometry has been described. The method is based on the generation of hydroxyl radicals in Fenton reaction and analysis of the product of their interaction with p-hydroxybenzoic acid - 3,4-dihydroxybenzoic acid. It has been found that the proposed assay is superior to the previously described chromatographic method with respect to analysis time. The method has been applied to the determination of TAP for some herbal extracts and melatonin.

The anti-oxidative properties of bitriazines (BTs) were evaluated using HPLC and cyclic voltammetry. In the first case, a RP-HPLC assay was made, using a fluorescence detector, hydroxyl radicals generated in Fenton reaction, and terephthalic acid as a spin trap. The measurements were performed using aqueous or methanolic solutions. It was found that when the BTs were dissolved in water they were antioxidants, while dissolved in methanol they were pro-oxidants. Their different physicochemical properties in both solvents were confirmed by voltammetric, chromatographic as well as spectrophotometric measurements.

HPLC has been already used for the TAP estimation. Phenylalanine, salicylic, p-hydroxybenzoic (pHBA) or terephthalic (TPA) acids have been used as sensor compounds. Products of their reaction with the hydroxyl radicals, generated in the Fenton-like reaction, were analyzed using electrochemical or fluorescence detection. This paper describes the TAP assay based on the hydroxyl radicals reaction with pHBA, reversed-phase-HPLC separation and UV photometric detection. The elaborated assay has been used to evaluate TAP values of some apiculture products.