## 1 Introduction  
Berries, thanks to their distinctive color, specific taste and aroma, high content of vitamins and minerals, as well as their wide use in the food process industry, play an important role among other fruits. Moreover, they can grow in extreme conditions, in which a majority of other fruit species do not grow. They are widely distributed. A rich variety of species grows in the North America, particularly in the USA and Canada [1,2]. _Rubus_ L. (_Rosaceae_) berries, due to their nutritional and bioactive value, arouse interest all over the world. Red raspberry (_Rubus ideas_ L.), an herbaceous plant in the _Rosaceae_ family, is a bush described as a nanofemorophyte. Raspberries are prized by both nutritionists and herbalists, due to their high content of pro-health substances [3]. A chemical constitution of raspberries leaves, which are a by-product of raspberry processing, has not been studied as thoroughly as its fruit. In particular, the healing properties of raspberry leaves, known since antiquity, are prescribed for the treatment of a wide variety of diseases, for example, by including them in herbal preparations used for the uterus relaxation during childbirth. Other applications of raspberry leaves include their use as an additive to drinks, nutritional supplements, preparations of functional herbal teas, teas, and chocolate, in order to enhance their nutritive and flavour-forming properties [4, 5]. It has been revealed that _Rubus_ berries are an increasingly important source of bioactive substances due to their anti-oxidant, anti-inflammatory, chemoprerative and antibacterial properties, their positive effects on blood lipids and above-mentioned atherosclerosis, as well as their advantageous composition. Therefore, thanks to their biological effect, they can potentially be applied as health-promoting [6]. The development of an increasing number of diseases has been attributed to the action of oxygen free radicals. Some of these diseases are caused by a shift in the cell's oxidoreductase-tive balance toward excessive free radical production by the mitochondria or as a result of uncontrolled inflammation (e.g., diabetes, atherosclerosis, or rheumatoid arthritis). Others, such as cancer, are due to disruptions in intracellular signal transduction or gene expression. Still others are due to impaired antioxidant mechanisms, particularly a reduction in GSH (glutathione) or impaired SOD (superoxide dismutase) activity. Free radicals are responsible for complications in transplantation, as well as heart attacks and strokes; they also lead to the development of Parkinson's and Alzheimer's diseases, some prenatal complications, lung and intestinal diseases, cataracts, male infertility, and poisoning [7, 8]. There are non-enzymatic and enzymatic mechanisms in the body that protect against the excess and harmful effects of free radicals. Non-enzymatic mechanisms are based on chemical reactions mainly involving vitamin E in cell membranes, vitamin C in the cytoplasm, and phenolic compounds. Scientists emphasize the biological importance of polyphenic compounds as effective antioxidants. These are secondary metabolites widespread in the plant world (mostly in the form of glycosides or esters) that are not synthesized in animal organisms. Polyphenols can act in several ways: as reducing agents, as free radical blocking compounds, chelating metal ions that catalyze oxidation reactions (thus preventing reactions caused by a single active oxygen atom), and inhibiting the activity of oxidative enzymes such as lipoxygenases. Polyphenols have an ideal chemical structure for capturing free radicals and for forming chelates with metals, making them much more effective in vitro antioxidants than antioxidant vitamins [9, 10]. Carotenoids exhibit a broad spectrum of antioxidant activity, and they are classified as both preventive and interventional antioxidants. They are divided into two subgroups: carotenes and xanthophylls.