Antioxidant activity of Sophora exigua and liposome development of its powerful extract

Sophora exigua (SE) was sequentially extracted using hexane, ethyl acetate, and ethanol. The obtained extracts were tested for antioxidant activity. Among them, the fractionated ethyl acetate extract (SE-EA) showed the highest potential in free radical scavenging and ferric-reducing properties. The chemical analysis identified sophoraflavanone G as one of the active ingredients in SE-EA. According to SE-EA solubility, SE-EA liposomes were developed using a sonication-assisted thin film method. Cholesterol and phospholipids were used as the main compositions of the liposomes. The obtained liposomes were spherical with different nano-size ranges, size distribution, and zeta potential depending on SE-EA and total lipid concentrations. SE-EA liposomes were slightly bigger than their empty liposomes. All liposomes exhibited a phospholipid crystalline structure. Cholesterol and SE-EA existed in the liposomes as an amorphous state. SE-EA liposomes with high total lipid content exhibited high entrapment efficiency and sustained release behavior. Whereas liposomes with low total lipid content showed low entrapment efficiency and fast-release behavior. All SE-EA liposomes showed stronger antioxidant activity than the non-entrapped SE-EA. In conclusion, SE-EA is a natural source of potent antioxidants. The developed SE-EA liposomes are a promising pharmaceutical formulation to efficiently deliver the active ingredients of SE-EA and are suitable for further study in vivo.