Enhancement of solubility, thermal stability and bioaccessibility of vitexin using phosphatidylcholine-based phytosome

Vitexin is a C-glycosylated flavonoid which has many biological activities. However, extremely low aqueous solubility and poor bioaccessibility of vitexin greatly limits its application. In this study, phytosome technology was applied to improve these limitations using soybean phosphatidylcholine (SPC) and egg yolk phosphatidylcholine (EPC) as carrier agents. The effect of types of carrier agents and ratios of vitexin to carrier agent on the physicochemical properties, solubility, and thermal stability of vitexin-loaded phytosomes was investigated. The phytosome produced using EPC showed high encapsulation yield of 97.60%, encapsulation efficiency of 98.27%, solubility of 89.15%, total phenolic content (TPC) of 114.44 mg GAE/g phytosome, ferric reducing antioxidant power (FRAP) of 15.77 mmol Trolox/g phytosome and DPPH radical scavenging activity of 9.49 mmol Trolox/g phytosome. The phytosomal preparations using the ratio of vitexin to EPC of 1:3 could improve physical and chemical properties of vitexin-loaded phytosomes. Furthermore, phytosome technology could promote greater bioaccessibility and antioxidant activity of vitexin under thermal and simulated gastrointestinal digestion conditions compared to unprocessed vitexin. The results suggest that phytosome technology has ability to overcome the limitation and enable the application of vitexin.