Medium pH and macronutrients content affects growth and production of secondary metabolites by Drosera plants

Carnivorous plants have always been fascinating to humans. Sundew (Drosera) has been known since middle ages as a plant with a wide application in herbal and folk medicine. The infusion or tincture was used as antitussive drug and painkiller, as well as a remedy for intimate infections and gastrointestinal diseases. Today we know that the biological activity of Drosera is mainly due to the high content of flavonoids and naphthoquinones, as well as cyanogens, proteolytic enzymes, anthocyanins and organic acids. Most of these compounds are plant secondary metabolism products. Secondary metabolites are a kind of plant’s weapon, protecting against threats (bacteria, fungi, insects) and adverse environmental conditions (unsuitable soil pH, unavailability of minerals, UV radiation). The substances of plant origin are also used in various industries as flavouring additives, dyes, natural preservatives or active ingredients of medicines. It has been shown that extracts from Drosera plants, rich in naphthoquinones, may have anti-cancer (Ahmad, Banerjee, Wang, Kong, & Sarkar, 2008) and bactericidal effects, even against multiresistant bacteria (Krolicka et al., 2009).