Jagiellonian University, Faculty of Chemistry, Gronostajowa 2, 30-387, Kraków, Poland; Jagiellonian University, Doctoral School of Exact and Natural Sciences, Łojasiewicza 11, 30-348, Kraków, Poland.
Jagiellonian University Medical College, Chair of Microbiology, Department of Infections Control and Mycology, Czysta 18, 31-121, Kraków, Poland.
Arch Biochem Biophys. 2024 Nov;761:110178. doi: 10.1016/j.abb.2024.110178. Epub 2024 Oct 10.
The aim of this work was to investigate the effect of monoterpenoid hinokitiol (β-thujaplicin) on the monolayers and bilayers composed of lipids typical for bacteria membranes and gain insight into the potential role of the lipids in antibacterial activity and selectivity of this compound. To explore this issue, the in vitro studies were performed on different bacterial strains to verify antibacterial potency of hinokitiol. Then, the experiments on E. coli and S. aureus bacteria membrane models (i.e. multicomponent lipid monolayers and bilayers) were done. Finally, the effect of hinokitiol on one component lipid monolayers was investigated. The lipids used in the experiments included Phosphatidylethanolamines (PEs), Phosphatidylglycerols (PGs) and Cardiolipins differing in the structure of the polar head and/or the hydrophobic chains. This choice allowed the analysis of correlations between the lipid structure and the effect of hinokitiol. In vitro tests confirmed the antimicrobial activity of hinokitiol against most of the strains tested. In addition, the in vitro tests showed that E. coli bacteria were more sensitive to hinokitiol than S. aureus bacteria. Interestingly, the studies on model systems evidenced that hinokitiol molecules are of stronger effect on E.coli film and they are able to insert into these systems even at membrane-related surface pressures. Moreover, the structure of the lipid and its content in the model system correlated with the effect exerted by hinokitiol on the monolayer properties. It was found that hinokitiol differs in the affinity to particular lipids and additionally hinokitiol/lipid interactions may occur according to different mechanisms. Namely, depending on the lipid structure, hinokitiol may incorporate into the lipid film (Cardiolipins and PEs) or interact preferentially with the lipid polar head (PGs) and form hydrogen bonds. The effect of hinokitiol on the lipids was determined by the charge and size of the polar head as well as by the spatial size of the lipid molecule. Moreover, comparing the lipids of the same polar heads, hinokitiol caused stronger expansion of the film formed from the lipid having unsaturated chains. The results obtained may explain the difference in the effect of hinokitiol on particular bacterial strains. In conclusions, it can be suggested that the lipids should be considered as the bacteria membrane structural elements of a possible role in the mechanism of action of hinokitiol.
本工作旨在研究单萜烯 hinokitiol（β-雪松醇）对细菌膜脂组成的单层膜和双层膜的影响，深入了解该化合物抗菌活性和选择性的潜在作用。为了探索这个问题，我们在不同的细菌菌株上进行了体外研究，以验证 hinokitiol 的抗菌效力。然后，我们在大肠杆菌和金黄色葡萄球菌的膜模型（即多组分脂质单层膜和双层膜）上进行了实验。最后，我们研究了 hinokitiol 对单组分脂质单层膜的影响。实验中使用的脂质包括磷脂酰乙醇胺（PEs）、磷脂酰甘油（PGs）和心磷脂，它们在极性头和/或疏水链的结构上有所不同。这种选择允许分析脂质结构与 hinokitiol 作用之间的相关性。体外测试证实了 hinokitiol 对大多数测试菌株的抗菌活性。此外，体外测试表明，大肠杆菌比金黄色葡萄球菌对 hinokitiol 更敏感。有趣的是，模型系统的研究表明，hinokitiol 分子对大肠杆菌膜的影响更强，即使在与膜相关的表面压力下，它们也能够插入这些系统。此外，脂质的结构及其在模型系统中的含量与 hinokitiol 对单层性质的影响相关。研究发现，hinokitiol 对特定脂质的亲和力不同，并且 hinokitiol/脂质相互作用可能根据不同的机制发生。即，根据脂质结构，hinokitiol 可以嵌入脂质膜（心磷脂和 PEs）中，或者与脂质的极性头优先相互作用（PGs）并形成氢键。hinokitiol 对脂质的影响取决于极性头的电荷和大小以及脂质分子的空间大小。此外，比较具有相同极性头的脂质，hinokitiol 导致具有不饱和链的脂质形成的膜的扩张更强。所得到的结果可以解释 hinokitiol 对特定细菌菌株的影响的差异。总之，可以认为脂质应该被视为细菌膜结构元素，可能在 hinokitiol 的作用机制中发挥作用。
