Reactive oxygen species - sources, functions, oxidative damage.

Reactive oxygen species (ROS) are molecules capable of independent existence, containing at least one oxygen atom and one or more unpaired electrons. This group includes oxygen free radicals, e.g. superoxide anion radical, hydroxyl radical, hydroperoxyl radical, singlet oxygen, as well as free nitrogen radicals. Under physiological conditions, small quantities of ROS are formed during cell processes, such as aerobic respiration or inflammatory processes, mainly in hepatocytes and macrophages. Reactive oxygen species are primarily signalling molecules. In addition, they induce cell differentiation and apoptosis, thus contributing to the natural ageing process. They also participate in muscle contractions, regulation of vascular tone, and determine bactericidal and bacteriostatic activity. Increased production of free radicals is caused by excessive exposure to UV radiation, long-term stress conditions, intense physical exercise, improper diet and use of stimulants. Under physiological conditions, there is a balance between the generation and removal of free radicals from the body. The aim of the article was to review the current state of knowledge regarding oxidative stress, free radical function and free radical diseases. The search was performed using search engines such as PubMed and Google Scholar. The keywords used in the search included: oxygen radicals, oxidative stress, free radical-related diseases. Excessive formation of free radicals contributes to oxidative stress, causing damage at the molecular and cellular level. Reactive oxygen species in vitro cause chemical modifications as well as damaging effects to proteins (aggregation, denaturation), lipids (peroxidation), carbohydrates and nucleotides (changes in the DNA structure). These changes contribute to the development of many free radical-mediated diseases. Oxidative stress has a particularly adverse effect on the circulatory, respiratory and nervous systems.

Antioxidant properties of small-molecule non-enzymatic compounds.

Reactive oxygen species are molecules capable of independent existence, containing at least one oxygen atom and one or more unpaired electrons. Excessive formation of these molecules leads to oxidative stress. In recent years, there has been a growing interest in substances with antioxidant properties, reducing or preventing the harmful effects of free radicals. The compounds involved in antioxidant defence include endogenous and exogenous antioxidants, protecting body cells against the negative effects of oxygen radicals. The most important small-molecule non-enzymatic compounds found in food include ascorbic acid, retinol, ß-carotene, tocopherol and polyphenolic compounds. Products of plant origin may provide a valuable source of bioactive compounds with antioxidant properties. It is believed that a diet rich in antioxidants may reduce the risk of developing several nutrition-related conditions as well as delay the ageing process. The aim of this review was to elucidate this topic and the state of the art about the role of plant orgin substances in counteraction of free radical reactions in human body.

Antioxidant Properties and Nutritional Composition of Matcha Green Tea.

Matcha green tea (Camellia sinensis), which originates from Japan, is commonly considered as particularly beneficial to health. A large content of polyphenols, amino acids (mainly tannins) and caffeine potentially increase the antioxidant properties of the drink. The aim of the study was to determine the antioxidant potential and the content of substances with an antioxidant effect-vitamin C, total polyphenol content including flavonoids-in infusions made from Traditional Matcha (from the first and second harvests) and Daily Matcha (from the second and third harvests) at different temperatures. The infusions were made by pouring 100 mL of distilled water once at various temperatures (25 °C, 70 °C, 80 °C and 90 °C) over 1.75 g of the plant material. Matcha tea is characterized by a high level of antioxidant substances (flavonoids 1968.8 mg/L; polyphenols 1765.1 mg/L; vitamin C 44.8 mg/L) as well as antioxidant potential (41.2% DPPH (10× dilution); 6129.5 µM Fe(II)/dm3 FRAP). The concentration of these compounds depends on the time at which the plant material was harvested as well as on the temperature of water used to prepare the infusions. For most parameters, the highest values were observed in infusions prepared at 90 °C and from the daily Matcha.

Magnesium content, total antioxidant status and lipid peroxidation in rainbow trout (Oncorhynchus mykiss Walbaum).

The present study was aimed at evaluating magnesium content, ferric reducing antioxidant power (FRAP) and lipid peroxidation in selected tissues of rainbow trout during their development. For mineral and biochemical assay, samples of liver, kidney, gills and blood were taken from fish. Magnesium concentration ranged between 35.5 and 249.2 mg·kg⁻¹ wt/wt. Most magnesium was found in the gills and the less in kidneys. FRAP values in the examined fish varied from 0.85 to 4.64 nmol Trolox Eq.mg⁻¹ protein. The highest FRAP was observed in the kidneys and the lowest in the gills. Concentration of malondialdehyde (MDA) in the examined tissue homogenates averaged 4.16-11.36 nmol·mg⁻¹ protein. We observed that levels of analyzed parameters increased during growth of the fish.