Morin-Loaded DPPC/Cholesterol Liposomes to Improve Chemical Stability and In Vitro Bioactivity

Background/Objectives: Morin is the first flavonoid isolated from plants in the Moraceae family and has been reported to exhibit anticancer and antioxidant activity. It is classified as a Class IV compound in the Biopharmaceutical Classification System due to its low water solubility and low permeability. This study aimed to develop and characterize morin-loaded liposomes composed of DPPC and cholesterol to improve their stability and anticancer activity. Methods: Liposomes were prepared by thin-film hydration and then processed by bath sonication, probe sonication, or membrane extrusion to control vesicle size. Formulations were characterized by hydrodynamic diameter, polydispersity index (PDI), zeta potential, encapsulation efficiency (EE), and colloidal stability over 7 days at 37 °C. The cytotoxic effects of free and encapsulated morin were evaluated in tumor (MDA-MB-231, B16F10) and non-tumor (NIH-3T3, HEK-293T) cell lines. Results: Extrusion yielded the most homogeneous liposomes (PDI = 0.2, size ≈ 90 nm), whereas sonication methods produced larger, more polydisperse vesicles. EE ranged from 11–17%, with no significant differences among methods. Free morin degraded by 40% at 37 °C after 7 days, whereas liposomal encapsulation significantly reduced degradation, preserving 82–89% of the compound. At a morin equivalent of 3.4 µM, the bath-sonicated formulation reduced viability to approximately 65% in MDA-MB-231 cells and 70% in B16F10 cells, whereas viability remained approximately 86% in NIH-3T3 cells and 82% in HEK-293T cells. All formulations maintained colloidal stability over the study period. In cytotoxicity assays, free morin showed minimal activity, whereas liposomal formulations significantly enhanced antiproliferative effects against cancer cells. Conclusions: These findings demonstrate that DPPC/cholesterol liposomes effectively stabilize morin and improve its bioactivity, representing a promising strategy for delivering this flavonoid in anticancer therapies.