The aim of the current study was to analyze the stability of rosmarinic acid in ethanolic tinctures of lemon balm (Melissa officinalis L.), oregano (Origanum vulgare L.), peppermint (Mentha x piperita), rosemary (Rosmarinus officinalis L.), sage (Salvia officinalis L.), and thyme (Thymus vulgaris L.). High-performance liquid chromatography with diode-array detection (HPLC–DAD) was employed to monitor the concentration of the marker compound over a six month period. Furthermore, the tinctures were also evaluated for caffeic acid, total phenolic content, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity. We observed that the concentration of rosmarinic acid in tincture stored in closed amber glasses at ambient temperature decreased significantly during 6-month storage. Furthermore, our study squarely confirms the fact that a part of rosmarinic acid is converted to caffeic acid. The tested tinctures can be listed in the following order according to the greatest stability of the marker compound: rosemary > peppermint > oregano > lemon balm > thyme > sage. The results of the study indicated a linear relationship between DPPH values and total phenolic (R² = 0.92) or rosmarinic acid (R² = 0.85) contents.

本研究的目的是分析迷迭香酸在柠檬香脂 ( Melissa officinalis L.)、牛至 ( Origanum vulgare L.)、薄荷 ( Mentha x piperita )、迷迭香 ( Rosmarinus officinalis L.)、鼠尾草 ( Salvia officinalis L.) 和百里香 ( Thymus vulgarisL.）。使用带有二极管阵列检测器的高效液相色谱 (HPLC-DAD) 监测六个月内标记化合物的浓度。此外，还评估了酊剂的咖啡酸、总酚含量和 2,2-二苯基-1-苦基肼 (DPPH) 清除活性。我们观察到，在室温下储存在密闭琥珀色玻璃杯中的迷迭香酸浓度在 6 个月的储存期间显着降低。此外，我们的研究直接证实了一部分迷迭香酸转化为咖啡酸的事实。测试的酊剂可以根据标记化合物的最大稳定性按以下顺序列出：迷迭香>薄荷>牛至>柠檬香脂>百里香>鼠尾草。R ²  = 0.92) 或迷迭香酸 ( R ²  = 0.85) 含量。