Co-encapsulation of milk thistle and barberry extracts in beta-sitosterol-modified phytosomes: Formulation and characterization

This study introduces a novel approach for co-encapsulating milk thistle and barberry extracts within a beta-sitosterol-modified phytosomal system. Beta-sitosterol was incorporated into the phospholipid bilayer to enhance structural integrity. Phytosomes were prepared using the thin-layer hydration method with varying beta-sitosterol ratios. The optimal formulation (active component:Soy phosphatidylcholine: beta-sitosterol = 1:0.8:0.2) had a particle size of 240 nm and showed improved characteristics: reduced polydispersity index (0.18), high zeta potential (-47 mV), and enhanced encapsulation. Encapsulation efficiency reached 77% for silymarin and 81% for anthocyanins, indicating potential for dual delivery of lipophilic and hydrophilic compounds. In vitro gastrointestinal release studies showed a condition-dependent pattern. Anthocyanins exhibited higher gastric release (≈25.7% at 120 min) due to their hydrophilic nature, while silymarin showed limited gastric release (<8%). After transition to intestinal conditions, silymarin release markedly increased, reaching about 61.5% at 360 min. The inclusion of beta-sitosterol did not significantly affect release profiles. Fourier-transform infrared and differential scanning calorimetry analyses indicated hydrogen bonding between components. Field emission scanning electron microscopy images revealed more compact, spherical particles in modified phytosomes. These findings suggest this system may be useful for developing stable formulations in functional food or pharmaceutical applications. • A phytosomal system was developed to simultaneously encapsulate Milk Thistle and Barberry extracts, representing a novel dual-delivery strategy. • Beta-sitosterol modification of the lipid bilayer contributed to improved particle integrity and overall formulation uniformity. • The formulation allowed differential release of the two extracts, reflecting their hydrophilic and lipophilic properties. • Encapsulation efficiency of both herbal actives was enhanced, supporting effective loading within the carrier. • FTIR and DSC analyses suggested potential interactions between the extracts and the lipid matrix, indicating the robustness of the system.