Fermented aqueous extracts of Viscum album L. are widely used for cancer treatment in complementary medicine. The high molecular weight compounds viscotoxins and lectins are considered to be the main active substances in the extracts. However, a vast number of small molecules (≤1500 Da) is also expected to be present, and few studies have investigated their identities. In this study, a comprehensive metabolome analysis of samples of fermented aqueous extracts of V. album from two host tree species (Malus domestica and Pinus sylvestris), both prepared by two pharmaceutical manufacturing processes, was performed by liquid chromatography−high resolution tandem mass spectrometry (LC-HRMS/MS). A total of 212 metabolites were putatively annotated, including primary metabolites (e.g., amino acids, organic acids, etc.) and secondary metabolites (mostly phenolic compounds). A clear separation between V. album samples according to the host tree species, but not due to manufacturing processes, was observed by principal component analysis. The biomarkers responsible for this discrimination were assessed by partial least squares−discriminant analysis. Because V. album extracts from different host trees have different clinical applications, the present work highlights the possibility of characterizing the metabolome for identification and traceability of V. album fermented aqueous extracts.

Macrophyte extracts inhibit cyanobacteria growth, offering a sustainable solution for bloom control. The present study aimed to evaluate Microcystis aeruginosa’s response to aqueous extracts obtained from the dried biomass of Pistia stratiotes L. and Pontederia crassipes Mart. Solms. Physiological parameters analyzed included growth, photosynthesis, and antioxidative response. Reactive oxygen species generation and the chemical profile of the aqueous extracts were analyzed. At 4.0 g L ^-1 , both extracts inhibited cyanobacterial growth in 6 days. P. stratiotes extract achieved 100% inhibition, while P. crassipes extract reached 60%. P. stratiotes extract showed higher photosynthetic inhibition (99% vs. 12% for P. crassipes ). This was related to the downregulation of the psbA gene (coding for the photosystem II protein D1). Exposure to both extracts increased intracellular reactive oxygen species content in cyanobacterial cells and increased peroxiredoxin gene ( prxA) transcripts. This response was not noted for sod (superoxide dismutase) transcripts, although SOD enzymatic activity increased in cultures exposed to P. stratiotes extracts. Upon incubation of the macrophyte extracts with M. aeruginosa cultures, phenol concentrations decreased, and their general metabolic profile changed. Thus, P. stratiotes extract outperformed P. crassipes , inhibiting M. aeruginosa growth, affecting photosystem II, and inducing oxidative stress. Highlights: Aqueous extracts from dried biomass of P. stratiotes and P. crassipes inhibited M. aeruginosa growth. P. stratiotes extract suppressed photosystem II activity, while P. crassipes did not Both extracts elicited ROS production in cells. Peroxiredoxin gene expression upregulated by extract exposure. P. stratiotes extract increased SOD activity in cells.