Qualitative Phytochemical Profiling and Antimicrobial Activity of Viscum album L. Extracts Obtained by Microwave-Assisted Extraction: Influence of Milling Pretreatment

This study compared a defined milling pretreatment with a non-milling preparation of Viscum album L. plant material subjected to microwave-assisted extraction (MAE) with 70% (v/v) aqueous ethanol under identical operating conditions. The milled material was processed for 30 s using a laboratory mill, whereas the non-milled material was cut into smaller fragments. Total extractive matter (TEM) increased with time and reached the maximum after 20 min, with values of 5.52 and 5.01 g/100 g plant material for milled and non-milled samples, respectively. Qualitative UHPLC-DAD-MS/MS analysis revealed that the most dominant compounds in both extracts are organic acids, phenolic acids and flavonoid glycosides, followed by chlorophyll derivatives, coumarin glucosides and sesquiterpenoids. Both extracts demonstrated antimicrobial potential against Bacillus cereus, Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Proteus vulgaris, Pseudomonas aeruginosa and Candida albicans. The MAE process that used the milled plant material had lower specific energy consumption, referred to as the TEM amount, together with the overall process cost. According to the differences in TEM yield, qualitative phytochemical profile and antimicrobial activity of the extracts, the milled Viscum album L. plant material is recommended to be used for future MAE optimization experiments in order to obtain extracts that can have different applications.