## 1 Introduction  
_Armillaria mellea_ (Vahl) P. Kumm., also called honey mushroom, is an edible wild-growing mushroom commonly harvested and consumed in many countries, e.g., in Eastern Europe, and in China and the United Kingdom. Young fruiting bodies of _A. mellea_ are attractive culinary products due to their flavor and texture as well as nutritional value. This species has been found to possess large amounts of consumptionally and pharmaceutically valuable compounds, including polysaccharides, proteins, terpenoids, indole compounds, sterols, minerals, and vitamins [1]. Among them, polysaccharides have been found to exhibit different pharmacological activities, such as immunomodulatory, antioxidant, and anticancer properties [2]. A study of _A. mellae_ fruiting bodies harvested in China revealed that water-soluble polysaccharides from this species possess strong antitumor activities against the lung cancer cell line through the mitochondria-dependent pathway and activation of the caspase cascade via the release of cytochrome c [3]. Several in vivo studies have revealed an impact of polysaccharides from Chinese species of _A. mellae_ on the immune system, i.e., enhancement of the immunological function in mice and improvement of the immune ability of mice by adjusting the immunocyte and cytokine. Additionally, protective effects against cyclophosphamide-induced damage to murine bone marrow cells have been revealed [4]. [PERSON] et al. [5] found that polysaccharides from the honey mushroom from China were useful as a potential immunopotentiating agent, since they stimulated the murine lymphocyte proliferation induced by concanavalin A or lipopolysaccharideacharide. Moreover, the antioxidant activities of different types of extracts from cultured mycelia of _A. mellae_ have been evaluated. The available data indicate that water or ethanolic extracts can be used to reduce oxidative damage in the organism and prevent free radical-related diseases [6;7]. In recent years, it has been demonstrated that polysaccharides from _A. mellae_ can be used as potential agents against diabetes. Neutral polysaccharides from this species enhanced insulin sensitivity in vitro, and lowered the blood glucose level and modulated lipid metabolism in mice [8].  
All the aforementioned findings were revealed for specimens obtained in East Asia, most of which were cultivated. The knowledge of the composition and medicinal potential of polysaccharides obtained from _A. mellae_ growing in the wild in Eastern Europe has remained limited so far. Meanwhile, it was previously observed that the geographic and climatic conditions influence chemical profile and biological effects of wild-growing mushrooms [9].  
Since _A. mellae_ is one of the most frequently collected mushrooms in Poland, the aim of our study was to investigate the broad health-beneficial activity of crude polysaccharides (AmPS) from wild-growing honey mushrooms for the first time, including their antioxidant, anti-inflammatory, antidiabetic, and antiproliferative potential. The chemical composition of AmPS was evaluated using various spectrophotometric methods. Moreover, high-performance capillary electrophoresis and \({}^{1}\)H-nuclear magnetic resonance (\({}^{1}\)H NMR) were employed for the identification of the monosaccharide composition.