Thymol essential oil/ β-cyclodextrin inclusion complex into chitosan nanoparticles: Improvement of thymol properties in vitro studies

Thymol (TH) is a natural compound extracted from plants. In the present study, the β-cyclodextrin (βCD) complex of TH as the main constituent of thyme essential oil, was synthesized by freeze-drying (FD) method and TH/βCD inclusion complexes loaded chitosan (CS) nanoparticles (NPs). Phase solubility studies presented that the formation of inclusion complex enhanced water solubility of TH in the presence of βCD also the stability constant was obtained 965 M−1. The TH/βCD-ICs and TH/βCD-CS NPs were characterized using UV–Vis absorption, FT-IR, 1HNMR, XRD, and SEM. Moreover, the theoretical study of molecular modeling demonstrated the most desirable mode of TH encapsulated into the βCD cavity. Complexes exhibited 1:1 host: guest stoichiometry. The antibacterial effect of TH/βCD-ICs and TH/βCD-CS NPs was investigated against gram-positive Staphylococcus aureus and gram-negative Escherichia coli bacteria. The antioxidant test indicated that complexes exhibited better antioxidant activities compared to the pure TH through free radical scavenging assay.