Preparation and characterization of inclusion complexes of Nigella sativa seed oil with β-cyclodextrin: in vitro biological applications and in silico assessment

Nigella sativa seed oil is widely used as an anti-inflammatory, antioxidant, and anticancer agent. However, its insolubility in aqueous media and low stability limit its practical biological applications. The aim of this study was to formulate and characterize Nigella sativa seed oil (NO) using β-cyclodextrin (β-CD). The preparation of the inclusion complexes was carried out by co-precipitation method and then validated by Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), differential scanning calorimetry (DSC), and dynamic light scattering (DLS). The encapsulation efficiency of the inclusion complexes formed was about 80.4% and 88.2% for the two ratios studied, 1:2 and 1:4 (w:w), respectively. The study showed that the Nigella oil encapsulation preserved the antioxidant activity against DPPH and, in particular, enhanced the antibacterial activity against Salmonella typhimurium, Staphylococcus aureus, and Bacillus cereus by a factor reaching fourfold. A minimum inhibitory concentration similar to that of ampicillin (0.078 mg/mL) was observed against Salmonella typhimurium when the complex β-CD/NO 1:4 (w:w) was used. The cytotoxicity study showed that the oil encapsulation in β-CD retained its anti-proliferative activity against HeLa cancer line cells. Using SwissADME prediction, the pharmacokinetic profile of all identified oil compounds was evaluated to define their absorption, distribution, metabolism, and excretion (ADME) properties. The results support the use of encapsulated Nigella oil for active food packaging or pharmaceutical formulations.