Design and optimization of chitosan microspheres loaded with green tea phytosomes for sustained release

Background: Phytosomes are nanovesicular systems that integrate plant extracts with phospholipids to improve the solubility, stability, and bioavailability of phytoconstituents. Green tea (Camellia sinensis) is rich in polyphenols such as epigallocatechin gallate (EGCG) and epigallocatechin (EGC), which possess significant therapeutic potential but are limited by poor absorption and stability. The present study aimed to formulate and evaluate green tea extract–loaded phytosome-incorporated microspheres with desirable physicochemical characteristics for sustained delivery. Methodology: Phytosomes were prepared using the thin-layer hydration method with varying molar ratios (0.5–1.0) of phospholipids to standardized green tea extract (sample 1 and sample 2). The optimized phytosomes were further encapsulated into microspheres via emulsion cross-linking, employing different concentrations of glutaraldehyde and polymer to obtain nine formulations. Design Expert software was applied for optimization, and the microspheres were evaluated for micrometric properties, entrapment efficiency, drug loading, drug release, swelling behaviour, mucoadhesion, stability, and surface morphology. Results and Discussion: The prepared microspheres exhibited a spherical morphology with satisfactory physicochemical properties. Among the formulations, batch F3 of sample 1 demonstrated the most promising results, achieving 87% yield, 77% drug entrapment efficiency, 30% drug loading, and 91.87% cumulative drug release up to 9 hours, along with favorable swelling and mucoadhesion properties. Stability studies further confirmed the reliability of the formulation. Conclusion: Overall, the developed phytosome-loaded microspheres of green tea extract exhibited an improved release profile, stability, and potential fwr sustained drug delivery, suggesting their applicability in enhancing the therapeutic efficacy of green tea polyphenols.