Enhanced\nAnti-Inflammatory and Skin Barrier Repair\nEffects of Nanoemulsions Supplemented with Boesenbergia\nrotunda for Atopic Dermatitis

Betamethasone dipropionate (BD) is a potent anti-inflammatory\ndrug\nfor atopic dermatitis (AD); however, it leads to serious adverse effects\nduring prolonged use. We aimed to improve the biochemical properties\nand lower the risk of toxicity by preparing nanoemulsions containing Boesenbergia rotunda rhizome hexane extract (Hex)\nand essential oils (EO). Physicochemical characterization and 3-month\nlong-term stability testing were conducted. Gas chromatography–mass\nspectrometry analysis was used to compare the volatile composition\nafter nanoemulsion formulation. Further, various assays related to\nAD management, including antioxidant potentials, anti-inflammatory\nactivities through inhibition of 5-lipoxygenase and cyclooxygenase-2,\nand nitric oxide release suppression in lipopolysaccharides-induced\nRAW 264.7 macrophages, were investigated. In addition, antibacterial\nactivity against Staphylococcus aureus and cytotoxicity to RAW 264.7 macrophages and HaCaT human keratinocyte\ncells were also evaluated. Monodispersed nanoemulsions (<20 nm)\nwere successfully generated by an ultrasound-assisted method. BD was\nsuccessfully encapsulated into B. rotunda-based nanoemulsions with more than 95% encapsulation efficiency\n(EE). The major phytochemicals present in EO and Hex remained after\nnanoemulsion formulation. The nanoemulsions were compatible with skin\npH (5.2–5.8) and exhibited stability with respect to particle\nsize, polydispersity index, transmittance, pH, and EE when stored\nfor 3 months at −20 °C. The BD nanoemulsions loaded with B. rotunda exhibited antioxidant activities and significantly\nincreased the 5-lipoxygenase inhibitory activity. Furthermore, the\nsuppression of nitric oxide release was remarkably enhanced, whereas\nlower cytotoxicity was observed. The BD nanoemulsions improved the\nlevel of involucrin and filaggrin in HaCaT cells, implying their valuable\nproperty for skin barrier repair. The formulation of BD into nanoemulsions\nalso enhanced S. aureus inhibition.\nEither B. rotunda nanoemulsions loaded\nwith or without BD show promise for the topical treatment and prevention\nof AD.