Aims: The aim of this study was to conduct antimicrobial analysis on novel Schiff base-derived cobalt(II) complexes (Co(L1)2 and Co(L2)2). Methodology and results : Synthesis of Co(II) Schiff base complexes was carried out by reacting Schiff bases with cobalt(II) chloride hexahydrate and spectroscopic analyses were used for characterization. Microbiological assays comprised the determination of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of tested substances and the evaluation of their antibiofilm activity. A total of 11 bacteria were tested, including multidrug-resistant strains. Investigated compounds performed inhibitory activity against all tested bacteria, with the MIC value of 250 µg/mL and 125 µg/mL just for Escherichia coli ATCC 14169. Results regarding the antibiofilm properties suggest that investigated Schiff’s base complexes have antibiofilm activity in a strain-specific and concentrationdependant manner. Conclusion, significance and impact of study: The current study showed that the novel complex compounds possess antimicrobial and antibiofilm properties against Gram-positive and Gram-negative bacteria. Since bacterial resistance to currently available antibiotics is rapidly increasing, further studies may provide information about using novel complexes as potential antimicrobial agents.

Aims: Candida albicans is a regular member of the human microbiota but also one of the most frequent pathogens with a strong biofilm-forming capacity and prominent resistance to antimycotic drugs. The aim of this investigation was to evaluate the anti-C. albicans biofilm activity of ethanolic and methanolic leaf extracts of spinach, Swiss chard and garden orache. Methodology and results: Antifungal activity was established by determining the minimum inhibitory (MIC) and minimum fungicidal concentrations (MFC) by the broth microdilution method. The antibiofilm activity was tested by the tissue culture plate method, followed by the determination of the biofilm inhibition. Results showed that all extracts exhibit antifungal activity, with the MIC value of 62.50 μg/mL. This is in accordance with the results of antibiofilm activity, where extracts showed the ability to decrease the biofilm-forming capacity at sub-inhibitory concentrations. Overall antibiofilm effect of spinach extracts were narrow, but biofilm inhibition activity was observed at 31.25 μg/mL of ethanolic extract. Considering the dilution range, garden orache extracts had the broadest antibiofilm activity, with a biofilm inhibition of 20.96-38.10% and 12.11-12.97% for ethanolic and methanolic extracts, respectively. Swiss chard ethanolic extract inhibited biofilm from 14.52% to 31.39% and methanolic from 37.66% to 44.70%. Conclusion, significance and impact of study Study revealed that investigated plant extracts have antifungal and antibiofilm potential against C. albicans, which could be important in light of its emerging resistance to synthetic drugs, as well as the possible toxicity of antimycotics.
Antifungal Agents ; Biofilms ; Plant Extracts