Targeting transportation of curcumin by soybean lipophilic protein nano emulsion: Improving its bioaccessibility and regulating intestinal microorganisms in mice

Curcumin is widely recognized for its essential role in human health but is limited by its poor solubility and low bioaccessibility. This study attempts to address these limitations by preparing a delivery system for curcumin using a stabilized emulsion from soybean lipophilic protein nanoparticles (SLP-NPs). The results show that the concentration of SLP-NPs had significant effects on droplet size, zeta potential and emulsion microstructure. Rheological analysis indicated that SLP-NPs emulsion exhibited a viscoelastic liquid structure marked by its shear-thinning behavior and a higher loss modulus compared to the storage modulus. Meanwhile, as a carrier of bioactive substances, SLP-NPs can encapsulate curcumin, and the encapsulation rate reached 77.13%. Stability experiment showed that curcumin soybean lipophilic protein nanoparticles emulsion (Cur-SLP) showed good storage stability. The simulated in vitro digestion assay showed that SLP-NPs embedding increased the bioaccessibility of curcumin (76.14%), thus allowing the targeted release of curcumin in the small intestine. In addition, the gut microflora plays a crucial role in health. Therefore, based on improving the bioaccessibility of curcumin, we innovatively explored the regulatory effect of Cur-SLP on mice intestinal flora and designed an in vivo experiment. In vivo experiments have shown that Cur-SLP regulates the gut microorganism of mice, leading to increased abundance of health-promoting bacteria (Bifidobacterium). Notably, Cur-SLP significantly reduced the proportion of Firmicutes/Bacteroidetes. This study proves that SLP-NPs are an effective transport material for curcumin, providing an optimal choice for the application of hydrophobic active substances.