Hop leaves: From waste to a valuable source of bioactive compounds – A multidisciplinary approach to investigating potential applications

• Published in: Heliyon 2024-09, Vol.10 (18), p.e37593, Article e37593
• Main Authors: Sabbatini, Giulia, Mari, Eleonora, Ortore, Maria Grazia, Di Gregorio, Alessandra, Fattorini, Daniele, Di Carlo, Marta, Galeazzi, Roberta, Vignaroli, Carla, Simoni, Serena, Giorgini, Giorgia, Guarrasi, Valeria, Chiancone, Benedetta, Leto, Leandra, Cirlini, Martina, Del Vecchio, Lorenzo, Mangione, Maria Rosalia, Vilasi, Silvia, Minnelli, Cristina, Mobbili, Giovanna
• Format: Article
• Language: English
• Subjects: Alzheimer disease; amyloid; Anti-amyloid; antimicrobial properties; Antioxidant; antioxidant activity; antioxidants; beers; biomass; Biomass recycle; bovine serum albumin; circular economy; cosmetics; dietary supplements; drugs; Gram-positive bacteria; humans; Humulus lupulus; insulin; mucins; peptides; polyphenols; Synergistic antimicrobic; terpenoids; wastes
• ISSN: 2405-8440; 2405-8440
• DOI: 10.1016/j.heliyon.2024.e37593

After harvesting of cones used for beer production, the remaining hop vegetative biomass requires disposal. The hop plant contains bioactive compounds in all its parts—cones, leaves, and roots—exhibiting interesting antioxidant, antiviral, and antibacterial properties. In this work, extracts obtained from hop leaves, a plant material often neglected in the hop cultivation, have been investigated; the qualitative UHPLC-MS/MS and GC-TOF-MS characterization revealed the presence of bioactive compounds such as polyphenols, α- and β-acids and terpenes are present. The extract retained antioxidant activity, as verified by Folin-Ciocalteu, DPPH, ABTS and FRAP assays, and demonstrated some antimicrobial activity when combined with antibiotics, particularly against Gram-positive bacterial strains. Additionally, the extracts showed an ability to interact with proteins as human insulin, amyloid beta peptide, mucin and bovine serum albumin (BSA), has been detected, indicating their potential to counteract inflammatory processes and protect against Alzheimer's disease. These findings suggest that hop vegetative biomass, typically considered waste, can be potentially transformed into a valuable resource with applications in various fields, from nutraceuticals to pharmaceuticals and cosmetics, aligning with a circular economy perspective. [Display omitted] •Biomass from hop (Humulus lupulus L.) leaves can be a matrix to extract bioactive compounds.•Leaf extracts maintain antioxidant properties.•The extracts with antibiotics showed a synergistic to additive effect.•Leaf extracts exhibit anti-amyloid and anti-denaturation properties.•Hop leaves can switch from a by-product of beer-making process to a resource.