Antibiofilm Activity of Sundew Species Against Multidrug-Resistant Strains

Species of the genus , known for carnivorous plants, such as sundew, have been traditionally used for centuries as medicinal plants. Efficacy-determining compounds are naphthoquinones and flavonoids. Flavonoids possess a broad spectrum of bioactive properties, including biofilm inhibitory activity. Biofilms render antibiotics ineffective, contributing to the current rise in antimicrobial resistance. In this study, the biofilm inhibitory activity of two European sundew species ( and ) grown agriculturally in Germany and four commercial sundew products (declared as , sp. and Drosera planta trit.) against three multidrug-resistant strains was tested. The aim of the study was to comparatively investigate the biofilm inhibitory potential of sundew species extracts grown locally in northern Germany and commercial sundew products. The minimum biofilm inhibitory concentration of the European sundew species was approx. 35 µg mL. In comparison, commercial sundew products ranged in concentration from 75 to 140 µg mL. Additionally, individual compounds isolated from European sundew were tested. Among these compounds, biofilm inhibitory activity was determined for four of the eight substances, with 2″-O-galloyl hyperoside standing out for its activity (38 µg mL). The whole plant extracts of and proved to be more effective than the commercial products and the single compounds in its biofilm inhibition activity against strains. Sundew extracts may serve as a potential therapeutic approach for targeting biofilm production.