Strong antimicrobial activity of xanthohumol and other derivatives from hops (Humulus lupulus L.) on gut anaerobic bacteria

Abstract

Strong antimicrobial activity of xanthohumol and other derivatives from hops (Humulus lupulus L.) on gut anaerobic bacteria. APMIS 2017; 125: 1033-1038.Anaerobic bacteria, such as Bacteroides fragilis or Clostridium perfringens, are part of indigenous human flora. However, Clostridium difficile represents also an important causative agent of nosocomial infectious antibiotic-associated diarrhoea. Treatment of C. difficile infection is problematic, making it imperative to search for new compounds with antimicrobial properties. Hops (Humulus lupulus L.) contain substances with antibacterial properties. We tested antimicrobial activity of purified hop constituents humulone, lupulone and xanthohumol against anaerobic bacteria. The antimicrobial activity was established against B. fragilis, C. perfringens and C. difficile strains according to standard testing protocols (CLSI, EUCAST), and the minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBC) were calculated. All C. difficile strains were toxigenic and clinically relevant, as they were isolated from patients with diarrhoea. Strongest antimicrobial effects were observed with xanthohumol showing MIC and MBC values of 15-107 lg/mL, which are close to those of conventional antibiotics in the strains of bacteria with increased resistance. Slightly higher MIC and MBC values were obtained with lupulone followed by higher values of humulone.Our study, thus, shows a potential of purified hop compounds, especially xanthohumol, as alternatives for treatment of infections caused by select anaerobic bacteria, namely nosocomial diarrhoea caused by resistant strains.

Phenolic Compounds from Humulus lupulus as Natural Antimicrobial Products: New Weapons in the Fight against Methicillin Resistant Staphylococcus aureus, Leishmania mexicana and Trypanosoma brucei Strains

“…Their effect on Bacillus , Streptomyces and Micrococcus strains was previously underlined [22,41]. Hops extracts are also able to combat some human pathogenic bacteria found in food, such as Clostridium perfringens and Listeria monocytogenes [42,43]. The screening conducted on some C. albicans strains showed that the spectrum of activity of hops extracts against these yeasts is weak, only two strains were susceptible to our extracts.…”

Potent antibacterial, antioxidant and toxic activities of extracts from Passiflora suberosa L. leaves

“…According to phytochemical results, though both extracts of P. suberosa contain tannins, saponins and flavonoids, only the methanol extract showed antibacterial activities. The MIC values of conventional antibiotics are in the range of 15–107 µg/mL ( Cermak et al, 2017 ) and observed MIC values for methanol extract of P. suberosa ranged from 10–13 µg/mL indicating high antibacterial activity of the plant extract. Gram-negative bacteria pose a huge challenge in modern days due to emerging drug resistance of these pathogens.…”

Exploration of isoxanthohumol bioconversion from spent hops into 8-prenylnaringenin using resting cells of Eubacterium limosum

“…In addition, also the aqueous solubility at room temperature of 8-PN almost triples for an increase in pH from neutral to pH 8 (from 3 to 8 mg L −1 ) (Riis et al 2007). The theoretic dissociated fraction of the weak acids was approached using the Henderson-Hasselbalch equation for a range of pKa values for bitter acids, IX and 8-PN (Verzele and De Keukeleire 1991;Simpson and Smith 1992;Hermans-Lokkerbol et al 1997;Irwin and Shoichet 2005;Cattoor 2012; NCBI 2019; PhytoHub 2019a, 2019b; PubChem 2019) and indeed confirmed pH 7.8-8 could be the most optimal value for fermentation (Fig. 5).…”