Characterization of Bioactive Compounds and Evaluation of Antimicrobial Activity of Humulus lupulus (L.) cv. Cascade Leaves Throughout the Growing Season

Hop (Humulus lupulus L.) is recognised for its abundance of bioactive compounds, which make it a valuable natural resource. While much of the research has focused on the cones, hop leaves remain relatively unexplored, particularly in terms of changes occurring throughout the plant's growing cycle. In this context, the present study aims to characterize extracts from the leaves of the hop variety ‘Cascade,’ harvested monthly over the growing season. The extracts obtained were evaluated for total (poly)phenolic content, antioxidant capacity, and (poly)phenolic profile using UPLC-ESI-QqQ-MS/MS. Additionally, their antimicrobial activity was assessed. The results highlighted the presence of bioactive compounds with antioxidant potential, with some variations observed at different stages of growth. Our analysis identified 29 distinct compounds, with their concentrations fluctuating throughout the plant's life cycle. Furthermore, the leaf extracts exhibited antimicrobial activity against Listeria monocytogenes and Staphylococcus aureus, particularly during the early stages of the plant's growth.