Propolis-loaded liposomes (ProLip) enhance macrophage-mediated immunomodulation and suppress breast cancer cell proliferation

Propolis, a natural remedy derived from bee by-products, is known for its immunomodulatory and anticancer properties. However, its clinical application is hindered by poor solubility and bioavailability. This study formulated a propolis-loaded liposome (ProLip) using the thin-film hydration technique (soy phospholipid-to-cholesterol ratio 6:1) to enhance its therapeutic effect. Encapsulation reduced the particle size of propolis from 402.77 ± 7.53 nm to 249.67 ± 5.79 nm and enhanced physicochemical properties, including a low polydispersity index (0.098 ± 0.02), highly negative zeta potential (-50.80 ± 0.10 mV), and improved solubility (water contact angle of 50.247°). FTIR analysis confirmed intermolecular interactions between phenolic groups in propolis and phospholipid carbonyl groups, while electron microscopy and surface morphology analysis revealed uniform structure and phagosomal localization in macrophages. Functionally, ProLip enhanced anti-inflammatory cytokine secretion (IL-10: 49.429 ± 0.38 pg/mL; IL-6: 40.488 ± 0.10 pg/mL) and suppressed pro-inflammatory mediators (TNF-α and IL-1β) by > 80%, indicating immunoregulatory potential. Electron microscopy confirmed ProLip internalization within macrophage endocytic compartments and reduced macrophage morphological damage compared to unencapsulated propolis, validating targeted delivery and protection capacity. Additionally, conditioned media from ProLip-treated macrophages significantly induced apoptosis (> 50%) and inhibited migration and invasion in MCF-7 breast cancer cells, supporting immune-mediated anticancer effects. These findings highlight ProLip's potential as a nanocarrier to enhance the bioavailability, cellular targeting, and therapeutic efficacy of stingless bee propolis in cancer immunotherapy.