Functionalized liposomes and phytosomes loading Annona muricata L. aqueous extract: Potential nanoshuttles for brain-delivery of phenolic compounds

Background: Multi-target drugs have gained significant recognition for the treatment of multifactorial diseases such as depression. Under a screening study of multi-potent medicinal plants with claimed antidepressant-like activity, the phenolic-rich Annona muricata aqueous extract (AE) emerged as a moderate monoamine oxidase A (hMAO-A) inhibitor and a strong hydrogen peroxide (H2O2) scavenger. Purpose: In order to protect this extract from gastrointestinal biotransformation and to improve its permeability across the blood-brain barrier (BBB), four phospholipid nanoformulations of liposomes and phytosomes functionalized with a peptide ligand promoting BBB crossing were produced. Methods: AE and nanoformulations were characterized by HPLC-DAD-ESI-MSn, HPLC-DAD, spectrophotometric, fluorescence and dynamic light scattering methods. Cytotoxicity and permeability studies were carried out using an in vitro transwell model of the BBB, composed of immortalized human microvascular endothelial cells (hCMEC/D3), and in vitro hMAO-A inhibition and H2O2 scavenging activities were performed with all samples. Results: The encapsulation/binding of AE was more efficient with phytosomes, while liposomes were more stable, displaying a slower extract release over time. In general, phytosomes were less toxic than liposomes in hCMEC/D3 cells and, when present, cholesterol improved the permeability across the cell monolayer of all tested nanoformulations. All nanoformulations conserved the antioxidant potential of AE, while phosphatidylcholine interfered with MAO-A inhibition assay. Conclusions: Overall, phytosome formulations registered the best performance in terms of binding efficiency, enzyme inhibition and scavenging activity, thus representing a promising multipotent phenolic-rich nanoshuttle for future in vivo depression treatment.