Nanoemulsification Enhances the Regenerative and Safety Profile of <i>Ocimum gratissimum</i> Essential Oil <i>In Vitro</i>

The essential oil of <i>Ocimum gratissimum</i> (OG) stands out as a multifunctional agent with antioxidant, anti-inflammatory, and antimicrobial properties, positioning it as a candidate for innovative cosmetic applications. However, its instability in aqueous formulations remains a key barrier to its practical use. Therefore, this study aimed to develop a nanoemulsion incorporating <i>Ocimum gratissimum</i> essential oil (NG) using a low-energy emulsification technique and comprehensively evaluate its biological properties. The chemical composition of OG was analyzed using gas chromatography-mass spectrometry (GC-MS). A series of <i>in vitro</i> cell-based assays and alternative testing methods were employed to evaluate the NG for its antioxidant and anti-inflammatory properties, cellular proliferation, migration, as well as cytotoxicity and overall safety. GC-MS analysis revealed β-ocimene, eugenol, and germacrene D as the major components of OG. The developed NG exhibited a particle size under 500 nm, low polydispersity index (<0.3), and negative zeta potential, maintaining physicochemical stability for up to 60 days at 4 °C. Although NG showed a lower antioxidant activity than OG in chemical assays (ABTS/DPPH), both formulations effectively reduced intracellular levels of superoxide, hydrogen peroxide, and nitric oxide in macrophages. Notably, NG inhibited TNF-α, IL-6, and IL-1 production, whereas OG only suppressed TNF-α. In fibroblast models, both NG and OG stimulated cell proliferation (BrdU assay) and migration (scratch assay). Safety evaluations confirmed low ocular irritability (HET-CAM and CAM-TBS) and no phototoxicity (NRU-3T3). These findings highlight that NG enhanced anti-inflammatory efficacy and biological compatibility and demonstrate its potential as a cosmetic ingredient for skin regeneration.