Antibacterial effects of cinnamon (Cinnamomum zeylanicum) bark essential oil on Porphyromonas gingivalis.

The objective of this study was to investigate the antibacterial effects of cinnamon (Cinnamomum zeylanicum) bark essential oil (CBEO) and its principal constituent cinnamaldehyde against Porphyromonas gingivalis and to elucidate the antibacterial mechanism. GC-MS analysis showed that cinnamaldehyde was the major constituent in CBEO (57.97%). The minimum inhibition concentrations (MICs) of CBEO and cinnamaldehyde were 6.25 µg/mL and 2.5 µM for P. gingivalis, respectively. Nucleic acid and protein leakage was observed with increasing concentrations of CBEO and cinnamaldehyde. Additionally, propidium iodide uptake assays revealed CBEO and cinnamaldehyde at 1 × MIC impaired P. gingivalis membrane integrity by enhancing cell permeability. Morphological changes in P. gingivalis cells were observed by scanning electron microscopy, which indicated cell membrane destruction. To further determine the anti-biofilm effect, relative biofilm formation and established biofilms were examined, which demonstrated that both CBEO and cinnamaldehyde at sub-MIC levels inhibited P. gingivalis biofilm formation by 74.5% and 67.3% separately, but only CBEO slightly decreased established biofilms by 33.5% at 4 × MIC. These results suggest the potential of CBEO as a natural antimicrobial agent against periodontal disease. Furthermore, cinnamaldehyde was confirmed to be the antibacterial substance of CBEO with inhibitory action against P. gingivalis.

[Synthesis and luminescence properties of a reactive ternary europium complex containing 1,10-phenanthroline].

With dibenzoylmethane (HDBM) as the first ligand and 5-acrylamido-1,10-phenanthroline as the secondary ligand, a new reactive ternary europium complex, Eu(DBM)3Aphen, was prepared and characterized by elemental analysis, IR spectra and TG-DTG. Its photophysical properties were studied by using UV, luminescence spectra, lifetime and quantum yield measurements. The complex Eu(DBM)3Aphen showed characteristic luminescence of europium ions under UV excitation. Compared with the complex Eu(DBM)2 AA reported in the literature, complex Eu(DBM)3Aphen exhibited much stronger luminescence intensity, higher monochromaticity, longer lifetime and higher efficiency. The results showed that the complex Eu(DBM)3Aphen would be not only a potential red-emitting material but also a reactive complex, which would provide a new way for the synthesis of rare earth polymer with outstanding luminescence properties.