Pharmaceutical Biology, Department Pharmacy, Ludwig-Maximilians University of Munich, Butenandtstraße 5-13, Munich 81377, Germany.
Pharmaceutical Biology, Department Pharmacy, Ludwig-Maximilians University of Munich, Butenandtstraße 5-13, Munich 81377, Germany.
Phytomedicine. 2019 Jul;60:152969. doi: 10.1016/j.phymed.2019.152969. Epub 2019 May 22.
Phylloxanthobilins are tetrapyrrolic natural products that arise from the degradation of chlorophyll. Phylloxanthobilins have been discovered roughly 10 years ago in the leaves of deciduous trees, and are now considered a compound class with high and still unexplored potential of bioactivities. To date, however, there are no reports on the occurrence of phylloxanthobilins in parts of a medicinal plant used for pharmaceutical preparations.
The relevance of Echinacea purpurea as medicinal plant is undoubtedly high, and a large variety of pharmaceutical preparations is available on the market, mostly for the treatment of the common cold. Nevertheless, its phytochemical profiling has been limited to analysis for previously characterized substances, and this has not explained all its pharmacological efficacies. We therefore set out to investigate the occurrence of phylloxanthobilins in Echinacea purpurea.
Phylloxanthobilins in leaf extracts of Echinacea purpurea were detected using analytical HPLC. Identified phyllobilins were purified from plant material and characterized by UV/Vis, mass spectrometry, MS/MS, and confirmed by co-injections with previously published phyllobilins from different sources. The anti-oxidant activity of selected isolated phylloxanthobilins was assessed by an in vitro ferric reducing antioxidant power (FRAP) assay; in addition, the ability to scavenge ROS in cells caused by hydrogen peroxide stimulation was determined by measuring HDCF-DA fluorescence and by assessing cellular GSH levels.
In extracts of Echinacea purpurea leaves, an unprecedented diversity of phylloxanthobilins was detected; surprisingly, not only in senescent yellow leaves, but also in green leaves with no visible chlorophyll degradation. Six phylloxanthobilins were identified and structurally characterized. The uptake of phylloxanthobilins by human endothelial kidney cells was demonstrated. When investigating the anti-oxidative activity of these natural products, a potent in vitro activity was demonstrated; in addition, phylloxanthobilins possess intracellular ROS scavenging ability and can prevent oxidative stress as assessed by total cellular GSH levels.
Phylloxanthobilins are important constituents of Echinacea purpurea extracts, and our first exploratory studies hint towards promising bioactivities of these natural products, which may be relevant for understanding Echinacea efficacies.
叶黄质bilins 是四吡咯天然产物，来源于叶绿素的降解。叶黄质 bilins 大约在 10 年前在落叶树的叶子中被发现，现在被认为是一类具有高但尚未开发的生物活性的化合物。然而，迄今为止，还没有关于药用植物部分存在叶黄质 bilins 的报道，这些植物被用于药物制剂。
紫锥菊作为药用植物的相关性无疑是很高的，市场上有大量的药物制剂，主要用于治疗普通感冒。然而，其植物化学特征仅限于对先前表征物质的分析，这并不能解释其所有的药理功效。因此，我们着手研究紫锥菊中是否存在叶黄质 bilins。
使用分析 HPLC 检测紫锥菊叶提取物中的叶黄质 bilins。从植物材料中分离和纯化鉴定出的叶黄质 bilins，并通过紫外/可见分光光度法、质谱、MS/MS 进行鉴定，并通过与来自不同来源的先前发表的叶黄质 bilins 进行共注射来确认。通过体外铁还原抗氧化能力（FRAP）测定法评估选定分离出的叶黄质 bilins 的抗氧化活性；此外，通过测量 HDCF-DA 荧光和评估细胞内 GSH 水平来测定其清除由过氧化氢刺激引起的细胞内 ROS 的能力。
在紫锥菊叶提取物中，检测到前所未有的叶黄质 bilins 多样性；令人惊讶的是，不仅在衰老的黄叶子中，而且在没有明显叶绿素降解的绿叶子中也有。鉴定并结构表征了 6 种叶黄质 bilins。证明了叶黄质 bilins 被人内皮肾细胞摄取。在研究这些天然产物的抗氧化活性时，显示出很强的体外活性；此外，叶黄质 bilins 具有细胞内 ROS 清除能力，并可通过总细胞 GSH 水平来防止氧化应激。
叶黄质 bilins 是紫锥菊提取物的重要成分，我们的初步探索性研究提示这些天然产物具有有前途的生物活性，这可能有助于理解紫锥菊的功效。
