Viljoen Alvaro, van Vuuren Sandy, Ernst Erika, Klepser Michael, Demirci Betul, Başer Husnu, van Wyk Ben Erik
Department of Pharmacy and Pharmacology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
J Ethnopharmacol. 2003 Oct;88(2-3):137-43. doi: 10.1016/s0378-8741(03)00191-0.
The essential oil composition and antimicrobial activity of Osmitopsis asteriscoides, a medicinal plant used in traditional herbal preparations in South Africa has been investigated. Three different antimicrobial methods (disc diffusion, minimum inhibitory concentration by micro-titer plate and time-kill studies) were comparatively evaluated against Candida albicans, Staphylococcus aureus and Pseudomonas aeruginosa. A preliminary screening was done using the disc diffusion method on nine bacterial and four fungal isolates. Minimum inhibitory concentrations showed some correlation with the disc diffusion method. However, time-kill studies appear to be a more superior method for determining antimicrobial activity of volatile compounds such as essential oils. Two moderately susceptible and one resistant organism were selected to further demonstrate the variability between the three methods. The antimicrobial activity of the essential oil, tested by means of time-kill methodology at concentrations ranging from 0.5 to 2% (v/v) indicate a strong fungicidal activity against Candida albicans and the oil was also found to be bacteriostatic against Staphylococcus aureus in a concentration-dependent manner. The essential oil rapidly reduced viable counts of Pseudomonas aeruginosa, but regrowth was noted after 240 min. The results have been generated in duplicate in separate microbiology laboratories using different time-kill methods and the results are congruent. The two major essential oil components camphor and 1,8-cineole were investigated indicating the positive antimicrobial efficacy of 1,8-cineole independently and in combination with camphor. In addition to (-)-camphor and 1,8-cineole, 40 compounds were identified by GC-MS in the hydro-distilled essential oil. The high concentration of cineole and camphor and their synergistic effect is presented as a possible explanation for the traditional use of Osmitopsis asteriscoides for treating microbe-related illnesses.
对南非传统草药制剂中使用的药用植物星状奥斯米托普斯（Osmitopsis asteriscoides）的精油成分和抗菌活性进行了研究。采用三种不同的抗菌方法（纸片扩散法、微量滴定板法测定最低抑菌浓度和时间杀菌研究），对白色念珠菌、金黄色葡萄球菌和铜绿假单胞菌进行了比较评估。使用纸片扩散法对9种细菌和4种真菌分离株进行了初步筛选。最低抑菌浓度与纸片扩散法有一定相关性。然而，时间杀菌研究似乎是一种更优越的方法，用于确定挥发性化合物如精油的抗菌活性。选择了两种中度敏感和一种耐药菌株，以进一步证明这三种方法之间的差异。通过时间杀菌方法在0.5%至2%（v/v）浓度范围内测试的精油抗菌活性表明，对白色念珠菌有很强的杀真菌活性，并且还发现该精油对金黄色葡萄球菌有浓度依赖性的抑菌作用。精油迅速降低了铜绿假单胞菌的活菌数，但在240分钟后观察到有再生长现象。这些结果在不同的微生物实验室使用不同的时间杀菌方法重复产生，结果是一致的。对两种主要的精油成分樟脑和1,8-桉叶素进行了研究，表明1,8-桉叶素单独以及与樟脑组合具有积极的抗菌效果。除了（-）-樟脑和1,8-桉叶素外，通过GC-MS在水蒸馏精油中鉴定出40种化合物。高浓度的桉叶素和樟脑及其协同作用被认为是星状奥斯米托普斯传统上用于治疗微生物相关疾病的可能解释。
