Bogdanova Katerina, Kolar Milan, Langova Katerina, Dusek Martin, Mikyska Alexandr, Bostikova Vanda, Bostik Pavel, Olsovska Jana
Department of Microbiology, Faculty of Medicine and Dentistry, Palacky University Olomouc, Hnevotinska 3, Olomouc, Czech Republic.
Research Institute of Brewing and Malting, PLC, Lipova 15, Prague, Czech Republic.
Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub. 2018 May 23. doi: 10.5507/bp.2018.026.
Our research focused on the antimicrobial effects of purified hop (Humulus lupulus L.) fractions including α-bitter acids (humulones), β-bitter acids (lupulones) and xanthohumol, and a commercial CO hop extract of bitter acids against reference and multi-resistant strains of Gram-positive and Gram-negative bacteria and against selected yeast strains.
In vitro testing of antimicrobial activity was performed according to standard testing protocols (EUCAST). The effects of hop extracts on bacterial/yeast strains at concentrations below MICs were also determined and the antimicrobial potential of hop extracts was compared with selected antibiotics using optical density measurement.
The fractions were effective not only against reference strains of Gram-positive bacteria but, more importantly, against their methicillin- and vancomycin-resistant variants. No antimicrobial effect was detected against Gram-negative bacterial strains. Among the tested substances, xanthohumol was identified as the hop fraction with the most potent antimicrobial properties. It was also found that hop substances exerted their antimicrobial effects at concentrations considerably lower than the determined MICs, with the strongest effect in case of α-bitter acids in enterococci.
The search for and research of new compounds with antimicrobial properties represents a possible solution to the current global problem of bacterial resistance. Our data suggest a desirable activity of hop fractions against some multi-resistant bacterial strains. Thus, hops might find use as a source of potential antimicrobial agents applicable in both human and veterinary medicine.
我们的研究聚焦于纯化的啤酒花（Humulus lupulus L.）组分的抗菌作用，这些组分包括α-苦味酸（葎草酮）、β-苦味酸（蛇麻酮）和黄腐酚，以及一种市售的啤酒花苦味酸CO提取物，针对革兰氏阳性和革兰氏阴性细菌的参考菌株及多重耐药菌株，还有选定的酵母菌株。
根据标准测试方案（EUCAST）进行抗菌活性的体外测试。还测定了啤酒花提取物在低于最低抑菌浓度（MICs）的浓度下对细菌/酵母菌株的影响，并使用光密度测量将啤酒花提取物的抗菌潜力与选定的抗生素进行比较。
这些组分不仅对革兰氏阳性细菌的参考菌株有效，更重要的是，对其耐甲氧西林和耐万古霉素的变体也有效。未检测到对革兰氏阴性细菌菌株的抗菌作用。在测试的物质中，黄腐酚被确定为具有最强抗菌特性的啤酒花组分。还发现啤酒花物质在远低于确定的MICs的浓度下发挥其抗菌作用，在肠球菌中α-苦味酸的情况下效果最强。
寻找和研究具有抗菌特性的新化合物是解决当前全球细菌耐药性问题的一种可能方案。我们的数据表明啤酒花组分对一些多重耐药细菌菌株具有理想的活性。因此，啤酒花可能会成为一种潜在抗菌剂的来源，可应用于人类和兽医学。
