Enhanced Stability of α-Mangostin-Rich Extract and Selective Cytotoxicity against Cancer Cells via Encapsulation in Antioxidant Nanoparticles (AME@NanoAOX)

α-Mangostin-rich extract (AME) shows promise as a functional ingredient for cancer chemotherapy. Here, we encapsulated AME in our originally designed antioxidant nanoparticles (NanoAOX) to increase its solubility and prevent oxidative degradation (AME@NanoAOX). In this study, two types of self-assembled polymers containing nitroxide radicals were engineered. These polymers were self-assembled into nanoscale particles in aqueous media, entrapping AME (abbreviated as AME@NanoAOX(B) and AME@NanoAOX(G)). These formulations considerably improved the stability of AME against oxidative degradation and exhibited different release profiles of α-mangostin under different pH conditions. Furthermore, AME-encapsulated nanoparticles exhibited potent cytotoxicity against various cancer cell lines, including human breast cancer (MCF-7), human lung cancer (A549), human colon cancer (Caco-2), human cervical cancer (HeLa), and human liver cancer (HepG2) cell lines, with minimal cytotoxicity in normal human mammary epithelial cells (hTERT-HME1), thus providing a high selectivity index (SI). These results indicated the promising feature of AME-encapsulated antioxidant nanoparticles (AME@NanoAOX) for cancer chemotherapy.