Evaluation of the Anticancer Effects of Warburgia salutaris Leaf Extracts: A Comparative Study of Both Liposomal-Encapsulated and Unencapsulated Extracts, with Mechanistic Insights into Apoptotic Signalling

Although medicinal plants possess vast biological properties, crude medicinal plant extracts often show limited therapeutic efficacy due to poor aqueous solubility, instability, and inadequate bioavailability, which restricts efficient intracellular delivery. As cancer is a genetic disease requiring intracellular and nuclear targeting, improved delivery systems are essential. Warburgia salutaris is traditionally used in Southern Africa and possesses reported anticancer and anti-inflammatory properties; however, its crude extracts exhibit suboptimal delivery characteristics. This study comparatively evaluated the anticancer effects of unencapsulated (WSN) and liposomal-encapsulated (WSE) crude leaf extracts, with emphasis on apoptotic mechanisms. Liposomal formulation was confirmed by FTIR, PXRD, and DLS, yielding stable nanoparticles (159.4 nm; PDI 0.114; +79.3 mV). Both WSN and WSE demonstrated efficacy and concentration-dependent cytotoxicity against MCF-7 breast cancer cells (IC₅₀ < 0.0195 mg/mL) with minimal toxicity toward Vero kidney cells and RAW 264.7 macrophages. Mechanistically, WSN induced rapid cytotoxicity with necrotic features, whereas WSE promoted regulated apoptosis. Apoptosis was validated by DAPI/PI staining, Annexin V/PI flow cytometry, mRNA expression levels of Bax, Bcl-2, and caspase-3 measured with RT-PCR and proteome profiling array, confirming activation of intrinsic and extrinsic pathways. Both extracts also reduced LPS-induced ROS production. LC-MS identified multiple bioactive phytochemicals. Overall, liposomal encapsulation enhanced therapeutic precision, stability, and selectivity cytotoxicity, supporting its development as a nanomedicine-based anticancer strategy.