Desenvolvimento e caracterização de nanoemulsão contendo o óleo essencial de Ocimum gratissimum

Abstract

The essential oil of Ocimum gratissimum (OG) has antioxidant, antiinflammatory, and antimicrobial properties, making it promising for cosmetic and therapeutic applications. However, its low solubility and stability in aqueous media limit its use in cosmetic formulations, with nanoemulsions serving as a strategy to improve its bioavailability and enhance its effects. This study aimed to develop and characterize a nanoemulsion containing Ocimum gratissimum essential oil (NG), evaluating its stability, safety, and biological efficacy. Gas chromatography-mass spectrometry (GC-MS) analysis identified β-ocimene, eugenol, and germacrene D as the major compounds of OG. NG was obtained using the low-energy method, exhibiting an average particle size within the nanometric range, a polydispersity index (PDI) lower than 0.3, and a negative Zeta potential, indicating good colloidal stability. The physicochemical stability was monitored for 60 days under different storage conditions (4°C, 25°C, and 45°C), with 4°C being the most favorable temperature, showing a controlled and progressive increase in particle size. The antioxidant activity, assessed by ABTS and DPPH assays, showed that NG preserved the antioxidant activity of OG. Intracellular antioxidant and anti-inflammatory activities were evaluated by inhibition of nitric oxide, superoxide anion, and hydrogen peroxide, and by suppression of cytokine production in macrophage cultures. Both NG and OG reduced superoxide, peroxide, and nitric oxide levels, maintaining antioxidant effects. NG significantly reduced TNF-α, IL-6, IL-1, while OG reduced only TNFα. In vitro fibroblast culture, both NG and OG stimulated fibroblast proliferation, as shown by the BrdU assay, and promoted cell migration in the Scratch assay, suggesting a beneficial effect on skin tissue repair. Safety assays showed that NG had low irritability (mean score of 4.1) in the CAM-TBS test and moderate irritability in the HET-CAM test (mean score of 9.2). The photohemolysis evaluation indicated low toxicity to erythrocytes and no phototoxicity in 3T3 fibroblasts, reinforcing the safety of the nanoemulsion upon light exposure. It is concluded that NG preserved or enhanced the biological activity of OG and exhibited a favorable safety profile. This study highlights the potential of Ocimum gratissimum nanoemulsion for cosmetic and therapeutic applications, emphasizing the need for further studies in in vivo models and long-term stability evaluations.