AIMS & OBJECTIVES: In this study, we synthesized thirteen derivatives of gallic acid and evaluated their antibacterial potential against seven multi-drug resistant bacteria, as well as cytotoxic effects against human embryonic kidney cell line in vitro. Methods: 13 compounds were successfully synthesized with moderate to good yield and evaluated. Synthesized derivatives were characterized by using nuclear magnetic resonance spectroscopy, mass spectrometry, and Fourier transformation infrared spectroscopy. Antibacterial activity was determined using microdilution while cytotoxicyt was assessed using MTT assay.
RESULTS: The results of antibacterial assay showed that seven out of thirteen compounds exhibited antibacterial effects with compound 6 and 13 being most potent against Staphylococcus aureus (MIC 56 μg/mL) and Salmonella enterica (MIC 475 μg/mL) respectively. On the other hand, most of these compounds showed lower cytotoxicity against human embryonic kidney cells (HEK 293), with IC50 values ranging from over 700 μg/mL.
CONCLUSION: Notably, compound 13 was found to be non-toxic at concentrations as high as 5000 μg/mL. These findings suggest that the present synthetic derivatives of gallic acid hold potential for further studies in the development of potent antibacterial agents.
OBJECTIVES: Here, the efficacy of graphene oxide (GO), a carbon-based nanomaterial, was tested against the biofilms and intracellular S. aureus invitro. Following that, the mechanism for the intracellular antimicrobial activities and GO toxicities was elucidated.
METHODS: GO antibiofilm properties were evaluated based on the disruption of biofilm structure, and the intracellular antimicrobial activities were determined by the survival of S. aureus in infected bovine mammary cells following GO exposure. The mechanism for GO intracellular antimicrobial activities was investigated using endocytosis inhibitors. GO toxicity towards the host cells was assessed using a resazurin assay.
RESULTS: At 100 ug/mL, GO reduced between 30 and 70% of S. aureus biofilm mass, suggesting GO's ability to disrupt the biofilm structure. At 200 ug/mL, GO killed almost 80% of intracellular S. aureus, and the antimicrobial activities were inhibited when cells were pre-treated with cytochalasin D, suggesting GO intracellular antimicrobial activities were dependent on the actin-polymerization of the cell membrane. At
MATERIALS AND METHODS: Matured, healthy and disease-free leaves of Eucalyptus globulus were collected. The leaves were washed under tap water and finally dried in an oven at a temperature of 45°C for 48 hours. The dried plants were ground in an electric blender to make them into a powder. The powder was mixed with 100% ethanol and kept it inside a shaker overnight at 35°C. The mixture was centrifuged for 10 minutes at 2,500 rpm. Three different concentrations (10%, 50%, and 100% v/v) were used as antibacterial agents. Chlorhexidine (0.2%) was considered as positive control and dimethyl formamide was considered as negative control against P. gingivalis and A. actinomycetemcomitans. The disc diffusion method was used to determine the extract's antibacterial activity against the test organisms. A digital Vernier caliper was used to measure the diameter of antibacterial activity showing the zone of inhibition in millimeters.
RESULTS: Eucalyptus globulus with 100% concentration showed a maximum zone of inhibition against A. actinomycetemcomitans and P. gingivalis (5.38 ± 0.32 mm, 4.82 ± 0.11 mm) followed by 50% and 10% accordingly. The negative control of dimethyl formamide showed a zone of inhibition of 0.48 ± 0.96 mm and 0.63 ± 0.20 mm against A. actinomycetemcomitans and P. gingivalis. The positive control of 0.2% chlorhexidine showed a zone of inhibition of 8.46 ± 1.02 mm and 7.18 ± 0.54 mm against A. actinomycetemcomitans and P. gingivalis. The ANOVA test showed a highly significant antibacterial efficacy in 0.2% chlorhexidine and 100% concentration Eucalyptus globulus.
CONCLUSION: A significant maximum zone of inhibition against A. actinomycetemcomitans and P. gingivalis was showed by 100% concentration of Eucalyptus globulus.
CLINICAL SIGNIFICANCE: Other than the systemic diseases treatment, Eucalyptus globulus also serves as an effective promising alternative to antibiotics in the prevention of oral infections because of the natural phytochemicals existing in them.
METHODS: The gacS and gacA genes were screened in 96 clinical CRAB isolates using PCR assay. Pellicle formation assay was performed in Mueller Hinton medium and Luria Bertani medium using borosilicate glass tubes and polypropylene plastic tubes. The biomass of the pellicle was quantitated using the crystal violet staining assay. The selected isolates were further assessed for their motility using semi-solid agar and monitored in real-time using real-time cell analyser (RTCA).
RESULTS: All 96 clinical CRAB isolates carried the gacS and gacA genes, however, only four isolates (AB21, AB34, AB69 and AB97) displayed the ability of pellicle-formation phenotypically. These four pellicle-forming isolates produced robust pellicles in Mueller Hinton medium with better performance in borosilicate glass tubes in which biomass with OD570 ranging from 1.984 ± 0.383 to 2.272 ± 0.376 was recorded. The decrease in cell index starting from 13 hours obtained from the impedance-based RTCA showed that pellicle-forming isolates had entered the growth stage of pellicle development.
CONCLUSION: These four pellicle-forming clinical CRAB isolates could be potentially more virulent, therefore further investigation is warranted to provide insights into their pathogenic mechanisms.
METHODS: C. tropicalis isolates from sterile specimens were collected over a 12-month period. Conclusive identification was achieved biochemically with the ID 32 C kit. Susceptibility to nine antifungal agents was carried out using the colourimetric broth microdilution kit Sensititre YeastOne YO10. Biofilm-producing capability was evaluated by quantifying biomass formation spectrophotometrically following staining with crystal violet.
RESULTS: Twenty-four non-repetitive isolates of C. tropicalis were collected. The resistance rates to the triazole agents were 29.2% for fluconazole, 16.7% for itraconazole, 20.8% for voriconazole and 8.3% for posaconazole-the pan-azole resistance rate was identical to that of posaconazole. No resistance was recorded for amphotericin B, flucysosine or any of the echinocandins tested. A total of 16/24 (66.7%) isolates were categorized as high biomass producers and 8/24 (33.3%) were moderate biomass producers. None of our isolates were low biomass producers.
CONCLUSION: The C. tropicalis isolates from our centre were resistant only to triazole agents, with the highest resistance rate being recorded for fluconazole and the lowest for posaconazole. While this is not by itself alarming, the fact that our isolates were prolific biofilm producers means that even azole-susceptible isolates can be paradoxically refractory to antifungal therapy.