Preparation, characterization and investigation of some biological activities of benzyl isothiocyanate/chitosan and violacin/alginate beads

The distribution systems of pharmaceuticals have been the subject of numerous studies aiming to enhance the bioavailability and efficacy of molecules with medical potential. Active molecule-loaded polymer-based micro-/nanocarrier systems contribute to controlled drug release, increased therapeutic efficiency, lower dosage (compared to traditional release systems), and reduced side effects. Isothiocyanates (ITCs) are phytochemicals naturally produced in plants of the Brassicaceae family, possessing anti-microbial and anti-cancer properties. However, despite their significant biological features, these molecules exhibit low water solubility, stability, and bioavailability. This thesis aims to develop a drug delivery system using chitosan and sodium alginate biopolymers for the release of Benzyl Isothiocyanate (BITC) and violacein (VIO). To this end, through the ionic gelation method, BITCchitosan/VIO-alginate beads were prepared, and their physicochemical properties were analyzed using FTIR and SEM. Furthermore, the anti-bacterial and anti-biofilm properties of these BITC-chitosan and VIO-alginate beads were assessed. BITC was observed to exhibit an anti-bacterial activity against S. aureus (20.6±0.5 mm) and E. coli (12.6±0.5 mm). It inhibited biofilm formation by 47.6% and 49.8% for S. aureus and P. aeruginosa, respectively. VIO extract produced an inhibition zone diameter of 12.5±0.7 mm for S. aureus and inhibited biofilm formation by 50% and 47.7% for S. aureus and E. coli, respectively. The average diameters of BITC-chitosan beads were calculated to be 1006.0±1.0 µm for BITC1, 902±0.9 µm for BITC2, 1013.0±0.7 µm for BITC3, and 978±0.7 µm for VIO-alginate beads. The SEM analysis revealed that the beads exhibited spherical and uniform morphologies. BITC2-chitosan and VIO-alginate beads had drug-loading capacities of 72% and 64%, respectively. BITC2-chitosan beads produced inhibition zone diameters of 14.4±0.5 mm and 17.0±0.5 mm for S. aureus and E. coli, respectively. Additionally, they inhibited biofilm formation viii by 49.3%, 48.2%, 42.7%, and 40.5% for S. aureus, E. coli, E. faecalis, and P. aeruginosa, respectively. VIO-alginate beads inhibited biofilm formation by 72.5%, 46.2%, 54.9%, and 48.5% for S. aureus, E. coli, E. faecalis, and P. aeruginosa, respectively. The results of this study support the potential use of BITC-chitosan and VIO-alginate beads as medical materials and food preservatives thanks to their significant anti-bacterial and anti-biofilm properties