Of female cancer survivors more than half had suffered from breast or gynaecological Belinostat nmr cancer [2]. 40% to 80% of these patients use complementary therapies additionally to well-established treatments [3–8]. This includes a variety of medicinal plants, but also acupuncture, psychosocial support, yoga, art therapies and others. These are supportive measures to control symptoms, improve quality of life, boost the immune system, and possibly prolong life. Sufficient evaluation is often lacking, however, of the extent to which these therapeutic goals are

achieved, as well as of issues relating to safety and mode of action. Medicinal plants in particular have a long history in the treatment of cancer and other conditions connected with tumours, and also play a major role in the development of new drugs today. Over 60% of currently used anti-cancer agents originally derive from natural sources such as plants, marine organisms and micro-organisms [9]. Across Europe, Viscum album L. extracts small molecule library screening (VAE or European mistletoe, not to be confused with the Phoradendron species or “”American mistletoe”") are among the most common herbal extracts applied in cancer treatment

[3, 7, 8, 10]. Viscum album is a hemi-parasitic shrub and contains a variety of biologically active compounds. Mistletoe lectins (ML I, II and III) have been most thoroughly investigated. MLs consist of two polypeptide chains: a carbohydrate-binding B-chain that can bind on cell surface receptors, which enables the protein to enter the cell [11–13]; and the catalytic A-chain which can subsequently inhibit protein synthesis, due to its ribosome-inactivating properties, by removing an adenine Resminostat residue from the 28S RNA of the 60S subunit of the ribosome [11]. Other pharmacologically relevant VAE compounds are viscotoxins and

other low molecular proteins, VisalbCBA (Viscum album chitin-binding agglutinin) [14], oligo- and polysaccharids [15, 16], flavonoids [17], vesicles [18], triterpene acids [19], and others [20, 21]. Whole VAE as well as several of the compounds are cytotoxic and the MLs in particular have strong apoptosis-inducing effects [22–24]. MLs also display cytotoxic effects on multidrug-resistant cancer cells (e.g. MDR + colon cancer cells [25]) and enhance cytotoxicity of anticancer drugs [26, 27]. In mononuclear cells VAE also possess DNA-stabilizing properties. VAE and its compounds stimulate the immune system (in vivo and in vitro activation of monocytes/macrophages, granulocytes, natural killer (NK) cells, T-cells, dendritic cells, induction of a variety of cytokines such as IL-1, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12, GM-CSF, TNF-α, IFN-γ (overview see [20, 21]).