Liposomal Avicequinone-B formulations: Aqueous solubility, physicochemical properties and apoptotic effects on cutaneous squamous cell carcinoma cells

Abstract Background Avicequinone-B (Naphtho[2,3-b]furan-4,9-dione) is a furanonaphthoquinone derivative. It is a hydrophobic compound with poor aqueous solubility, which may restrict its potential pharmaceutical and biomedical applications. Purpose We synthesized different liposomal formulations of Avicequinone-B, and measured their particle size, aqueous solubility, and physicochemical properties. In addition, we investigated the anticancer activity of liposomal Avicequinone-B in human cutaneous squamous cell carcinoma (SCC) cells. Methods Liposomal Avicequinone-B formulations were synthesized using the thin-film hydration method. Drug yield, encapsulation efficiency and aqueous solubility were determined by high performance liquid chromatography. Particle size and polydispersity index were measured by submicron particle size analyzer, and ultrastructural morphology was visualized by transmission electron microscopy. Thermal transitions were determined by differential scanning calorimetry. Anti-skin cancer activity was determined in HSC-1 cells (human cutaneous SCC cell line) using the MTS cytotoxicity assay, apoptosis was assessed by caspase-3/7 activity assay, mitochondrial membrane potential was determined by JC-10 assay, and signal transduction pathways were evaluated by Western blot analysis. Results Liposomal Avicequinone-B formulations showed adequate yield and high encapsulation efficiency. These liposomal formulations produced small, uniformly sized nanoparticles, and greatly increased the aqueous solubility of Avicequinone-B. Differential scanning calorimetry showed loss of thermal phase transitions. In addition, liposomal Avicequinone-B showed significant cytotoxic effect on HSC-1 cells, through reduction of mitochondrial membrane potential, increased cytosolic cytochrome- c level, increased cleaved caspase 8 level, and induction of apoptosis. This was mediated through activation of ERK, p38 and JNK signaling pathways. Conclusion Liposomal Avicequinone-B demonstrated improved aqueous solubility and physicochemical characteristics, and induced apoptosis in cutaneous SCC cells. Therefore, liposomal Avicequinone-B may have potential uses as a topical anti-skin cancer drug formulation in the future.