Polymer-Based Microencapsulation of Hedychium coronarium Rhizome Essential Oil for Enhanced Bioactivity Stability and...

Background: Plant-derived essential oils possess valuable bioactivities, but their application is limited by volatility and irritation, which may be addressed through natural polymer encapsulation. This study aimed to investigate the bioactivity of Hedychium coronarium rhizome essential oil and evaluate the effect of microencapsulation on its physicochemical characteristics, biological stability, and irritation profile. Methods: Essential oil was extracted from H. coronarium rhizomes by hydrodistillation and chemically characterized. Enzyme inhibitory activities against elastase, hyaluronidase, and tyrosinase were assessed. Microencapsulation was performed using gum Arabic or maltodextrin at 1-5% w/w oil loadings. The resulting powders were evaluated for morphology, entrapment efficiency, hygroscopicity, water activity, biological stability, and irritation potential using the hen's egg test on the chorioallantoic membrane. Results: The essential oil demonstrated strong enzyme inhibition, particularly against hyaluronidase (IC₅₀ = 0.1 ± 0.0 µg/mL), along with notable elastase and tyrosinase inhibition. Encapsulation significantly reduced irritation scores from 13.3 ± 1.4 for the free oil to 3.6-4.2 for encapsulated systems (p < 0.05). Gum Arabic produced rough, porous particles with lower hygroscopicity, while maltodextrin yielded smoother particles with lower water activity. Both encapsulated powders significantly enhanced biological stability compared with the ethanolic solution. Conclusions: Natural polymer-based microencapsulation effectively reduced the irritation potential and improved the handling properties of H. coronarium essential oil, supporting its potential application in topical bioactive delivery systems.