Rezk Ahmed, Nolzen Jennifer, Schepker Hartwig, Albach Dirk C, Brix Klaudia, Ullrich Matthias S
Molecular Life Science Research Center, Jacobs University Bremen, Campus Ring 1, Bremen, 28759, Germany.
Institute for Biology and Environmental Sciences, Carl von Ossietzky University Oldenburg, Carl von Ossietzky Strasse 9-11, Oldenburg, 26111, Germany.
BMC Complement Altern Med. 2015 Mar 18;15:67. doi: 10.1186/s12906-015-0596-5.
Plants are traditionally used for medicinal treatment of numerous human disorders including infectious diseases caused by microorganisms. Due to the increasing resistance of many pathogens to commonly used antimicrobial agents, there is an urgent need for novel antimicrobial compounds. Plants of the genus Rhododendron belong to the woody representatives of the family Ericaceae, which are typically used in a range of ethno-medical applications. There are more than one thousand Rhododendron species worldwide. The Rhododendron-Park Bremen grows plants representing approximately 600 of the known Rhododendron species, and thus enables research involving almost two thirds of all known Rhododendron species.
Twenty-six bacterial species representing different taxonomic clades have been used to study the antimicrobial potential of Rhododendron leaf extracts. Agar diffusion assay were conducted using 80% methanol crude extracts derived from 120 Rhododendron species. Data were analyzed using principal component analysis and the plant-borne antibacterial activities grouped according the first and second principal components.
The leaf extracts of 17 Rhododendron species exhibited significant growth-inhibiting activities against Gram-positive bacteria. In contrast, only very few of the leaf extracts affected the growth of Gram-negative bacteria. All leaf extracts with antimicrobial bioactivity were extracted from representatives of the subgenus Rhododendron, with 15 from the sub-section Rhododendron and two belonging to the section Pogonanthum. The use of bacterial multidrug efflux pump mutants revealed remarkable differences in the susceptibility towards Rhododendron leaf extract treatment.
For the first time, our comprehensive study demonstrated that compounds with antimicrobial activities accumulate in the leaves of certain Rhododendron species, which mainly belong to a particular subgenus. The results suggested that common genetic traits are responsible for the production of bioactive secondary metabolite(s) which act primarily on Gram-positive organisms, and which may affect Gram-negative bacteria in dependence of the activity of multidrug efflux pumps in their cell envelope.
传统上，植物被用于治疗多种人类疾病，包括由微生物引起的传染病。由于许多病原体对常用抗菌剂的耐药性不断增加，迫切需要新型抗菌化合物。杜鹃花属植物属于杜鹃花科的木本植物，通常用于一系列民族医学应用。全世界有一千多种杜鹃花。不来梅杜鹃公园种植了代表约600种已知杜鹃花的植物，从而使涉及几乎三分之二所有已知杜鹃花种类的研究成为可能。
使用代表不同分类进化枝的26种细菌来研究杜鹃叶提取物的抗菌潜力。使用从120种杜鹃花中提取的80%甲醇粗提物进行琼脂扩散试验。使用主成分分析对数据进行分析，并根据第一和第二主成分对植物源性抗菌活性进行分组。
17种杜鹃花的叶提取物对革兰氏阳性菌表现出显著的生长抑制活性。相比之下，只有极少数叶提取物影响革兰氏阴性菌的生长。所有具有抗菌生物活性的叶提取物均从杜鹃花亚属的代表植物中提取，其中15种来自杜鹃亚组，两种属于髯花杜鹃组。使用细菌多药外排泵突变体揭示了对杜鹃叶提取物处理的敏感性存在显著差异。
我们的综合研究首次表明，具有抗菌活性的化合物在某些杜鹃花种类的叶子中积累，这些杜鹃花主要属于一个特定的亚属。结果表明，共同的遗传特征负责生物活性次生代谢产物的产生，这些次生代谢产物主要作用于革兰氏阳性菌，并且可能根据其细胞膜中多药外排泵的活性影响革兰氏阴性菌。
