Abstract

Variation in chemical composition and biological activity of essential oils of medicinal plants may be observed due to the developmental stage of collected plant materials. In the present study, we compared the chemical compositions and antimicrobial activity of the essential oils from the aerial part of Thymus daenensis Celak. and Thymus fedtschenkoi Ronniger at different developmental stages. The highest essential oil content in both species was observed at the full flowering stage. The phenolic monoterpene thymol (71.9-73.9 %) and the monoterpene alcohol linalool (45.5-83.1 %) were the most abundant constituents at all phenological stages of T. daenensis and T. fedtschenkoi, respectively. All the essential oils possessed high antibacterial and antifungal activities against the microorganisms tested (Staphylococcus aureus, Bacillus cereus, Enterococcus faecium, Escherichia coli, Salmonella enteritidis, and Candida albicans), although of different degrees. The essential oils from T. fedtschenkoi appeared to be more active on almost all bacterial and fungal strains than that of T. daenensis (with MIC values of 1-16 mg/ml and 2-32 mg/ml, respectively). The effect of the plant phenological stage on the antimicrobial activity and constituents of T. fedtschenkoi essential oil was more pronounced than for T. daenensis. Interestingly, the antimicrobial effects of T. fedtschenkoi essential oil obtained at the seed set stage was noteworthy against all tested microorganisms, apart from the resistant E. faecium. Overall, this study highlighted the importance of the choice of the harvesting time to achieve the optimum of essential oil quality and quantity together with the antimicrobial activities, which are exploited in the pharmaceutical and food industries.

摘要

由于收集的植物材料的发育阶段，可能会观察到药用植物精油的化学成分和生物活性的变化。在本研究中，我们比较了来自百里香地上部分的精油的化学成分和抗菌活性。和Thymus fedtschenkoi Ronniger 处于不同的发育阶段。在完全开花阶段观察到两种物种中最高的精油含量。酚类单萜百里酚 (71.9-73.9 %) 和单萜醇芳樟醇 (45.5-83.1 %) 是T. daenensis和T. fedtschenkoi所有物候阶段最丰富的成分， 分别。所有精油对所测试的微生物（金黄色葡萄球菌、蜡状芽孢杆菌、屎肠球菌、大肠杆菌、肠炎沙门氏菌和白色念珠菌）都具有很高的抗菌和抗真菌活性，尽管程度不同。来自T. fedtschenkoi 的精油似乎对几乎所有细菌和真菌菌株的活性都高于T. daenensis（MIC 值分别为 1-16 mg/ml 和 2-32 mg/ml）。植物物候阶段对T. fedtschenkoi精油的抗菌活性和成分的影响比T. daenensis更明显。有趣的是，除了具有抗药性的粪肠球菌外，在种子凝固阶段获得的T. fedtschenkoi精油对所有测试微生物的抗菌作用都值得注意。总体而言，这项研究强调了选择收获时间的重要性，以实现最佳精油质量和数量以及在制药和食品工业中开发的抗菌活性。