Biological Activity of Hops (Humulus lupulus L.): Molecular Mechanisms and Significance for Human Health—A Review

Introduction/Objective: Common hop (Humulus lupulus L.) is a multi-component plant material that has been extensively studied for its antioxidant, anti-inflammatory, cardioprotective, metabolic, neuroprotective, immunomodulatory and anti-cancer properties. This review summarises current data on the molecular mechanisms of action of hop compounds, their therapeutic potential, metabolic interactions and biological significance, with particular emphasis on bioavailability, signalling pathways and organ-specific effects. Methods: A comprehensive literature review was conducted, covering in vitro and in vivo studies and available clinical trials analysing the biochemical activity, molecular targets and physiological effects of bioactive compounds in hops. Particular attention was paid to the regulation of oxidative stress, inflammatory signalling, mitochondrial function, metabolic pathways, interactions with the gut microbiota and their impact on the development of chronic diseases. Results: Bioactive compounds in hops modulate numerous key signalling pathways, including NF-κB, Nrf2, AMPK, MAPK, PPAR and PI3K/AKT/mTOR. They have been shown to reduce oxidative stress, inhibit the production of pro-inflammatory cytokines, regulate apoptosis, improve mitochondrial function, and activate endogenous antioxidant systems. Hops have a protective effect in cardiovascular diseases, metabolic disorders, neurodegenerative diseases and selected cancers through anti-inflammatory, anti-proliferative and metabolic mechanisms. In addition, hop compounds modulate the composition and activity of the gut microbiota, which promotes improved metabolic homeostasis. Despite relatively good intestinal absorption, systemic bioavailability remains limited; however, modern delivery systems significantly increase the stability and plasma concentrations of these compounds. Conclusions: Common hops have broad therapeutic potential due to their ability to regulate oxidative, inflammatory, metabolic and apoptotic processes at multiple levels. Their pleiotropic activity makes them a promising candidate for the prevention and treatment of chronic diseases. The development of delivery systems and consideration of the role of the gut microbiota may further increase its clinical application.