Palm oil nanoemulsion enhances tocotrienol stability, antioxidant, and selective anti-melanoma activity.

Tocotrienols (T3) have been known to have potential cytotoxic activity against cancer cells. However, their ability to effectively target cancerous tissue is hampered by their lipophilic characteristics and poor bioavailability. In this study, encapsulating T3 into nanoemulsions (NE) prepared from palm oil (5-20%) and Tween-80 (3-7%) assisted with ultrasonication (5-20 min) resulted in improved stability of NE-T3 (kinetic, thermodynamic, long-term storage) and biological activity. Response Surface Methodology with Box-Behnken Design predicted the significant effect of palm oil concentrations on nanosized particle formation, while Tween-80 concentration and ultrasonication time had minimal effect on particle size. The optimum formulation achieved nanoscale characteristics of NE-T3, including a mean particle size of 64.8 ± 8 nm, polydispersity index of 0.288, and ζ-potential of - 19.16 mV, with only 5.2 ± 0.8% size variation after 60-day storage at 40 °C. It also demonstrated condition-specific thermodynamic stability, long-term storage capability, controlled drug release properties (77.97 ± 4.41% cumulative release over 54 h), and significantly enhanced antioxidant activity. The antioxidant activity (ABTS and DPPH) of NE-T3 showed IC values of 26.63 ± 1.8 µg/mL (ABTS) and 9.38 ± 1.24 µg/mL (DPPH), representing 1.5-2.0-fold improvement over free form of T3. The NE-T3 significantly enhanced cytotoxicity (IC 45.07 ± 4.84 µg/mL) compared to free-T3 (IC 78.75 ± 4.68 µg/mL) in B16F0 melanoma cells, while both showed minimal toxicity on normal NIH-3T3 cells (IC > 230 µg/mL). Additional anticancer assays revealed that NE-T3 induced 12.83 ± 2.1% late apoptosis and caused G1 phase cell cycle arrest. This study highlights the potential of NE-T3 as a promising platform for r combinatory cancer therapies.