Green Antimicrobials: Innovative Applications of Hops Extracts as Biocontrol Agents

Natural compounds represent a fundamental source of antimicrobial agents with applications in numerous industries. This study investigates the antimicrobial properties of different fractions of extracts obtained from six hop varieties, as well as of certain compounds contained in hops and other plants. The results indicate that soft resins exhibit the strongest antibacterial activity among the hop-derived fractions evaluated, reaching a minimum MIC₉₀ value of 25 µg/mL (Fuggle variety) against Gram-positive bacteria (S. aureus) and 50 µg/mL (Chinook variety) against Gram-negative bacteria (E. coli). Furthermore, the composition of hops varies among varieties, resulting in divergent antimicrobial patterns, indicating the necessity for further research to elucidate the origins of these activities. Additionally, while hop-derived fractions exhibited noteworthy antibacterial properties, their antifungal activity against A. niger was found to be negligible. In addition, natural compounds such as carvacrol and thymol demonstrated the lowest MIC₉₀ values against E. coli (130 and 250 µg/mL, respectively) and S. aureus (280 and 250 µg/mL, respectively). Moreover, xanthohumol exhibited a better MIC₉₀ value against S. aureus (3 µg/mL), while no inhibitory effects were observed against E. coli. These insights highlight the necessity for further exploration of natural extracts in the development of new antimicrobial agents.