Merghni Abderrahmen, Belmamoun Ahmed Reda, Urcan Adriana Cristina, Bobiş Otilia, Lassoued Mohamed Ali
Laboratory of Antimicrobial Resistance LR99ES09, Faculty of Medicine of Tunis, University of Tunis El Manar, Tunis 1007, Tunisia.
Department of Agricultural Sciences, Faculty of Nature and Life Sciences, Djillali Liabes University, Sidi-Bel-Abbes 22000, Algeria.
Antioxidants (Basel). 2023 Jul 6;12(7):1388. doi: 10.3390/antiox12071388.
Due to the increased emergence of drug-resistant bacteria, the declining efficiency of traditional antimicrobials has generated severe concerns in recent years. Subsequently, more interest in other antimicrobial agents from natural resources draws more attention as an alternative to conventional medications. This study investigated the bactericidal mechanism of monoterpene 1,8-cineol (eucalyptol), a major compound of various essential oils, against methicillin-resistant (MRSA). The antibacterial activity of 1,8-cineol was assessed by an MTT assay against clinical and reference MRSA strains. A cell membrane integrity test, followed by zeta potential (ZP) measurements, was performed to evaluate the disruption of the bacterial membrane integrity. Additionally, the cytotoxic effect of this molecule on MRSA bacteria was investigated by monitoring reactive oxygen species (ROS) generation, lipid peroxidation (MDA), and antioxidant enzyme activities (CAT and SOD). Regarding the anti-staphylococcal effect, the obtained results revealed the antibacterial efficacy of 1,8-cineol wherein the minimum inhibitory concentrations were equal to 7.23 mg/mL. Furthermore, it enhanced membrane permeability, with a 5.36-fold increase in nucleic acid and protein leakage as compared with untreated strains, along with the alteration of surface charge (ZP) in MRSA cells. The tested compound caused an increase in ROS generation reaching 17,462 FU and MDA production, reaching 9.56 μM/mg protein, in treated bacterial cells, along with a decrease in oxidative stress enzymes activities. Our findings suggest that 1,8-cineol has the ability to damage the membrane integrity and induce ROS-mediated oxidative stress in MRSA cells, leading to its antagonistic effect against this pathogen and consequently aiding in the reversal of antibiotic resistance.
由于耐药菌的出现日益增多，近年来传统抗菌药物效率的下降引发了严重关注。随后，作为传统药物的替代品，对来自自然资源的其他抗菌剂的更多关注吸引了更多目光。本研究调查了单萜1,8-桉叶素（桉油精）——各种精油的主要成分——对耐甲氧西林金黄色葡萄球菌（MRSA）的杀菌机制。通过MTT试验评估了1,8-桉叶素对临床和参考MRSA菌株的抗菌活性。进行了细胞膜完整性测试，随后测量zeta电位（ZP），以评估细菌膜完整性的破坏情况。此外，通过监测活性氧（ROS）生成、脂质过氧化（MDA）和抗氧化酶活性（CAT和SOD），研究了该分子对MRSA细菌的细胞毒性作用。关于抗葡萄球菌作用，所得结果显示1,8-桉叶素具有抗菌功效，其最低抑菌浓度等于7.23 mg/mL。此外，它增强了膜通透性，与未处理菌株相比，核酸和蛋白质泄漏增加了5.36倍，同时MRSA细胞的表面电荷（ZP）也发生了改变。受试化合物使处理后的细菌细胞中ROS生成增加至17462 FU，MDA生成增加至9.56 μM/mg蛋白质，同时氧化应激酶活性降低。我们的研究结果表明，1,8-桉叶素能够破坏MRSA细胞的膜完整性并诱导ROS介导的氧化应激，从而对该病原体产生拮抗作用，进而有助于逆转抗生素耐药性。
