Development of flavonoid-loaded chitosan composite from Kalanchoe pinnata for antibacterial applications

The improper use of antibiotics in treating bacterial infections leads to the development of multi-drug-resistant strains. To address this issue, there is a growing demand for new antibiotic alternatives for the management of bacterial illnesses. In this study, we synthesized a cost-effective antibacterial composite with efficient performance, by loading Kalanchoe pinnata leaf-extracted flavonoids (KPFs) into a chitosan biopolymer matrix. The KPFs-loaded chitosan was characterized by spectroscopy and surface analyses. The synergistic antibacterial effects of the KPFs/chitosan composite were evaluated against bacterial isolates of Staphylococcus aureus, Bacillus subtilis, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Escherichia coli, demonstrating satisfactory data. The disc diffusion assays revealed inhibition zones ranging from 14 to 26.5 mm, while the minimum inhibitory concentrations and minimum bactericidal concentrations were found to be in the range of 10–15 µg/mL and 45–60 µg/mL, respectively. The kill-time kinetics study showed that all tested bacteria were killed in less than or within 6 h. In addition, the KPFs-loaded chitosan composite showed a clear significant improvement in the antibacterial effect as compared to its individual components (KPFs or chitosan alone). Conclusively, this research shows that plant-based antibiotics combined with functional natural polymers are sustainable and cost-effective solutions to fight bacterial infections.