Formulation and physicochemical characteristics of niosomes containing standardized hydroalcoholic extracts of eucalyptus (Eucalyptus galbie) and green tea (Camellia sinensis L.) with potential anti-acne effect

Background: Acne vulgaris, a chronic inflammatory condition of sebaceous glands, is often linked to microbial colonization (e.g., Cutibacterium acnes , Staphylococcus epidermidis, Staphylococcus aureus ) and inflammatory factors. This study explores the potential of Eucalyptus galbie and green tea ( Camellia sinensis ) extracts, delivered via niosomes, to combat acne. Niosomes, non-ionic surfactant vesicles, offer targeted drug delivery and improved pharmaceutical properties, particularly for topical applications. Methods: Eucalyptus and green tea extracts were obtained via hot maceration, standardized for phenolic and flavonoid content, respectively, and encapsulated into niosomes using the thin-film hydration method. Three final selected niosomess were characterized for particle size, physical stability, extract retention, and release study. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays were performed against S. aureus and S. epidermidis to evaluate antimicrobial activity. Results: Optimal niosomal formulations with varying ratios of cholesterol, tween 40, span 40, tween 60, and span 60 were prepared. The combination of span40:tween40:cholesterol (3.5:3.5:3) exhibited the most promising antimicrobial activity. This niosomal system demonstrated favorable particle size, stability, retention, and sustained release of the plant extracts. The MIC and MBC values against S. aureus and S. epidermidis were approximately 1250 µg/mL and 312.5 µg/mL, respectively. Conclusion: In conclusion, niosomal encapsulation of Eucalyptus and green tea extracts enhances their antibacterial effect, stability, and release profile compared to the non-niosomal form. The selected span40:tween40:cholesterol (3.5:3.5:3) niosome showed promise as an anti-acne product, warranting further toxicological and clinical evaluation.