Influence of silver content on rifampicin adsorptivity for magnetite/Ag/rifampicin nanoparticles.

Magnetite nanoparticles (NPs) decorated with silver (magnetite/Ag) are intensively investigated due to their application in the biomedical field. We demonstrate that the increase of silver content on the surface of nanoparticles improves the adsorptivity of antibiotic rifampicin as well as antibacterial properties. The use of ginger extract allowed to improve the silver nucleation on the magnetite surface that resulted in an increase of silver content. Physicochemical and functional characterization of magnetite/Ag NPs was performed. Our results show that 5%-10% of silver content in magnetite/Ag NPs is already sufficient for antimicrobial properties against Streptococcus salivarius and Staphylococcus aureus. The rifampicin molecules on the magnetite/Ag NPs surface made the spectrum of antimicrobial activity wider. Cytotoxicity evaluation of the magnetite/Ag/rifampicin NPs showed no harmful action towards normal human fibroblasts, whereas the effect on human embryonic kidney cell viability was time and dose dependent.

Antimicrobial efficacy of the combinations of Acacia nilotica,Murrayakoenigii (Linn.) Sprengel, Eucalyptus, and Psidiumguajava on primary plaque colonizers: An in vitro study.

BACKGROUND: The rise in disease incidence, increased resistance of pathogenic bacteria to currently used antibiotics and chemotherapeutics, opportunistic infections in immunocompromised individuals, and financial considerations in developing countries necessitates alternate preventive and treatment strategies for oral diseases. OBJECTIVE: The objective of the study is to assess the antimicrobial efficacy of triple and quadruple combinations of Acacia nilotica (AN), Murraya koenigii (Linn.) (MKL) Sprengel, Eucalyptus (Euca), and Psidium guajava (PS) on primary plaque colonizers. MATERIALS AND METHODS: The phytochemicals in four plants were extracted using Soxhlet apparatus. The dried extracts were diluted with dimethyl sulfoxide (DMSO) to prepare stock solutions (100 mg/ml) of each plant. The triple and quadruple combinations were prepared after mixing equal quantities of stock solutions from each plant extracts. The antimicrobial efficacy testing was done on Streptococcus mutans, Streptococcus sanguis, and Streptococcus salivarius using agar well diffusion method. Chlorhexidine of 0.2% composition and DMSO were used as positive and negative controls, respectively. The mean diameter of inhibition zone between different categories was compared using one-way analysis of variance. RESULTS: The combination of AN + MKL Sprengel + Euca + PS produced the highest mean diameter of inhibition zone (23.5 ± 2.17 mm) against S. mutans. The combination of AN + MKL Sprengel + Euca produced the maximum antimicrobial efficacy against S. sanguis (19.83 ± 1.33). CONCLUSION: All the triple and quadruple combinations of the plant extracts offered antimicrobial benefits either superior or comparable to 0.2% chlorhexidine against S. mutans, S. sanguis, and S. salivarius.

Copaifera reticulata oleoresin: Chemical characterization and antibacterial properties against oral pathogens.

Oral infections such as periodontitis and tooth decay are the most common diseases of humankind. Oleoresins from different copaifera species display antimicrobial and anti-inflammatory activities. Copaifera reticulata is the commonest tree of this genus and grows abundantly in several Brazilian states, such as Pará, Amazonas, and Ceará. The present study has evaluated the chemical composition and antimicrobial potential of the Copaifera reticulata oleoresin (CRO) against the causative agents of tooth decay and periodontitis and has assessed the CRO cytotoxic potential. Cutting edge analytical techniques (GC-MS and LC-MS) aided the chemical characterization of CRO. Antimicrobial assays included determination of the Minimum Inhibitory Concentration (MIC), determination of the Minimum Bactericidal Concentration (MBC), determination of the Minimum Inhibitory Concentration of Biofilm (MICB50), Time Kill Assay, and Checkerboard Dilution. Conduction of XTT assays on human lung fibroblasts (GM07492-A cells) helped to examine the CRO cytotoxic potential. Chromatographic analyses revealed that the major constituents of CRO were ß-bisabolene, trans-α-bergamotene, ß-selinene, α-selinene, and the terpene acids ent-agathic-15-methyl ester, ent-copalic acid, and ent-polyalthic acid. MIC and MBC results ranged from 6.25 to 200 µg/mL against the tested bacteria. The time-kill assay conducted with CRO at concentrations between 50 and 100 µg/mL showed bactericidal activity against Fusobacterium nucleatum (ATCC 25586) and Streptococcus mitis (ATCC 49456) after 4 h, Prevotella nigrescens (ATCC 33563) after 6 h, Porphyromonas gingivalis (ATCC 33277) and Lactobacillus casei (clinical isolate) after 12 h, and Streptococcus salivarius (ATCC 25975) and Streptococcus mutans (ATCC 25175) after 18 h. The fractional inhibitory concentration indexes (FICIs) revealed antagonistic interaction for Lactobacillus casei (clinical isolate), indifferent effect for Porphyromonas gingivalis (ATCC 33277), Fusobacterium nucleatum (ATCC 25586), Prevotella nigrescens (ATCC 33563), and Streptococcus salivarius (ATCC 25975), and additive effect for Streptococcus mutans (ATCC 25175) and Streptococcus mitis (ATCC 49456). Treatment of GM07492-A cells with CRO demonstrated that concentrations up to 39 µg/mL significantly reduced cell viability as compared to the negative control, being IC50 equal to 51.85 ± 5.4 µg/mL. These results indicated that CRO plays an important part in the search for novel sources of agents that can act against oral pathogens.