Surface-Modified Nanocarriers Encapsulating Brucine and Nigella Sativa Oil: A Novel Approach to Solid Tumor Therapy

Background: Using natural substances for cancer therapy has attracted considerable interest due to their safety and reduced systemic toxicity. Nigella sativa (NS) oil, a traditional natural oil rich in bioactive compounds, possesses significant therapeutic potential. Brucine (BR), an alkaloid, exhibits potent cytotoxicity against various cancer cell lines; however, its poor selectivity and high systemic toxicity limit its clinical application. Objective: To overcome these challenges, this study aimed to enhance drug delivery and improve therapeutic efficacy. Method: A PEGylated nanoemulsion (NE) incorporating NS and BR was developed and characterized for particle size, size distribution, zeta potential, viscosity, and drug content. The in vitro release of BR was evaluated both with and without serum incubation. A quantitative amount of serum protein associated with the surface of the NE was estimated, and a hemolytic safety assay was carried out. Finally, an in vitro cytotoxicity study was conducted, and the in vivo anti-tumor effect of the developed PEGylated BR-loaded NE was evaluated and compared with its naked counterpart. Result: The developed PEGylated BR-loaded NE possessed favorable characteristics as a nanocarrier for parenteral administration, with a particle size of 188.5 nm, a zeta potential of -1.61, a viscosity of 3.4 cP, and 99% drug content uniformity. It released up to 60.4% of BR over 12 h, while only 18.4 µg/µmol of the total lipids were adsorbed on the surface of the formulation, compared with 54.5 µg/µmol for the naked counterpart. The PEGylated NE was safe, inducing less than 5% of hemolysis, and displayed substantial inhibition of MDA cell growth. Conclusions: The PEGylated NE achieved a significant reduction in tumor volume, suggesting that PEGylated NE may serve as a promising platform for enhancing anti-tumor activity.