Chitosan nanoparticle encapsulation of <i>thymus capitatus</i> essential oil: <i>in vitro</i> release, antioxidant, antibacterial activity and cytotoxicity in MDA-MB-231 cells

<i>Thymus capitatus (Th. Ca)</i> is known to treat mouth ulcers and respiratory infections in Cyprus. However, antioxidant, antibacterial, and cytotoxic potential of <i>Th. Ca.</i> EO on MDA-MB-231 cells and its' encapsulation into nanoparticles has not been well studied. Therefore, we aimed to analyze the antioxidant, antibacterial, cytotoxic potential, loading efficiency, and <i>in vitro</i> release profile of both <i>Th. Ca.</i> EO and Chitosan Nanoparticle (Ch. Np) - <i>Th. Ca.</i> EO. GC-MS analysis revealed 53.97% carvacrol, 14.53% borneol, and 12.09% sabinene presence in EO. The loading efficiency of <i>Th. Ca.</i> EO into Ch. Np. was calculated as 35.27% and the <i>in vitro</i> release profile reached a maximum of 68% in pH 7 for two weeks. The Minimum Inhibitory Concentration (MIC) assay showed that <i>E. coli</i> had an MIC₅₀ of 0.3215 mg/ml while <i>B. subtilis</i> had an MIC₅₀ of 0.5304 mg/ml. The antioxidant activity of the EO was assessed by performing a DPPH assay with an IC₅₀ = 440 μg/ml. Trypan Blue Assay revealed that 60 µg/ml <i>Th. Ca.</i> EO significantly reduced the cell viability of MDA-MB-231 cells by 10.7% at 48h and 20.06% at 72h. Overall, Ch. Np. - <i>Th. Ca.</i> EO has shown a promising formulation for the pharmaceutical industry.