Department of Chemistry, Saint Peter's University, Jersey City, NJ 07306, USA.
Department of Biomedical Engineering, Chemistry, and Biological Sciences, Charles V. Schaefer School of Engineering and Sciences, Stevens Institute of Technology, Hoboken, NJ 07030, USA.
Phytomedicine. 2017 Jul 1;30:50-58. doi: 10.1016/j.phymed.2017.03.006. Epub 2017 Mar 30.
Most studies reveal that the mechanism of action of propolis against bacteria is functional rather than structural and is attributed to a synergism between the compounds in the extracts.
HYPOTHESIS/PURPOSE: Propolis is said to inhibit bacterial adherence, division, inhibition of water-insoluble glucan formation, and protein synthesis. However, it has been shown that the mechanism of action of Russian propolis ethanol extracts is structural rather than functional and may be attributed to the metals found in propolis. If the metals found in propolis are removed, cell lysis still occurs and these modified extracts may be used in the prevention of medical and biomedical implant contaminations.
The antibacterial activity of metal-free Russian propolis ethanol extracts (MFRPEE) on two biofilm forming bacteria: penicillin-resistant Staphylococcus aureus and Escherichia coli was evaluated using MTT and a Live/Dead staining technique. Toxicity studies were conducted on mouse osteoblast (MC-3T3) cells using the same viability assays.
In the MTT assay, biofilms were incubated with MTT at 37°C for 30min. After washing, the purple formazan formed inside the bacterial cells was dissolved by SDS and then measured using a microplate reader by setting the detecting and reference wavelengths at 570nm and 630nm, respectively. Live and dead distributions of cells were studied by confocal laser scanning microscopy.
Complete biofilm inactivation was observed when biofilms were treated for 40h with 2µg/ml of MFRPEE. Results indicate that the metals present in propolis possess antibacterial activity, but do not have an essential role in the antibacterial mechanism of action. Additionally, the same concentration of metals found in propolis samples, were toxic to tissue cells. Comparable to samples with metals, metal free samples caused damage to the cell membrane structures of both bacterial species, resulting in cell lysis.
Results suggest that the structural mechanism of action of Russian propolis ethanol extracts stem predominate from the organic compounds. Further studies revealed drastically reduced toxicity to mammalian cells when metals were removed from Russian propolis ethanol extracts, suggesting a potential for medical and biomedical applications.
大多数研究表明，蜂胶对细菌的作用机制是功能性的，而不是结构性的，这归因于提取物中的化合物之间的协同作用。
假设/目的：蜂胶据说可以抑制细菌的附着、分裂、抑制水不溶性葡聚糖的形成和蛋白质的合成。然而，已经表明，俄罗斯蜂胶乙醇提取物的作用机制是结构性的，而不是功能性的，这可能归因于蜂胶中发现的金属。如果去除蜂胶中发现的金属，仍然会发生细胞裂解，并且这些经过修饰的提取物可用于预防医学和生物医学植入物污染。
使用 MTT 和活/死染色技术评估不含金属的俄罗斯蜂胶乙醇提取物（MFRPEE）对两种生物膜形成细菌（青霉素耐药金黄色葡萄球菌和大肠杆菌）的抗菌活性。使用相同的活力测定法在小鼠成骨细胞（MC-3T3）细胞上进行毒性研究。
在 MTT 测定中，将生物膜在 37°C 下用 MTT 孵育 30 分钟。洗涤后，通过 SDS 溶解在细菌细胞内形成的紫色甲臜，并通过将检测和参考波长分别设置为 570nm 和 630nm，使用微孔板读数器进行测量。通过共聚焦激光扫描显微镜研究细胞的死活分布。
当用 2µg/ml 的 MFRPEE 处理生物膜 40 小时时，观察到完全的生物膜失活。结果表明，蜂胶中存在的金属具有抗菌活性，但在抗菌作用机制中没有重要作用。此外，在蜂胶样品中发现的相同浓度的金属对组织细胞有毒。与含金属的样品类似，不含金属的样品会破坏两种细菌的细胞膜结构，导致细胞裂解。
结果表明，俄罗斯蜂胶乙醇提取物的结构作用机制主要源自有机化合物。进一步的研究表明，当从俄罗斯蜂胶乙醇提取物中去除金属时，对哺乳动物细胞的毒性大大降低，这表明在医学和生物医学应用方面具有潜力。
