Comparative Study of Nanoparticle and Nanoemulsion of Vernonia amygdalina : Characterization and Pharmacological Activity

Nanotechnology-based delivery systems have become an effective strategy to enhance the physicochemical properties and biological activity of natural extracts in cosmetic formulations. This study comparatively evaluated nanoparticle (NDA) and nanoemulsion (NEDA) systems containing African leaf extract (Vernonia amygdalina) based on their physical characteristics and pharmacological activity. Nanoparticles were prepared via ionic gelation using Chitosan (15%) and NaTPP (1%), while nanoemulsions were prepared via waterbath sonication using Cremophor® RH (12%), PEG 400 (2%), and Oleic Acid (1%), each at three different concentration ratios. The extract yielded 13.56% with a total flavonoid content of 29.066±0.547 mg QE/g (2.907±0.055%), indicating a high bioactive compound content. Particle size analysis showed that the optimum nanoparticle formula (NDA 3) had a particle size of 91.5±0.74 nm, while the optimum nanoemulsion formula (NEDA 3) produced a smaller droplet size of 71.5±0.70 nm. Transmittance values ranged from 90.31–95.01% for nanoparticles and 93.01–96.43% for nanoemulsions, indicating good clarity and nanoscale particle dispersion. In antioxidant testing, NEDA 3 exhibited higher activity (IC50 86.697±1.042 ppm) than NDA 3 (IC50 251.947±3.457 ppm). Conversely, in anti-inflammatory testing, NDA 3 showed better activity (IC50 229.001±1.229 ppm) than NEDA 3 (IC50 325.612±0.927 ppm), with Diclofenac Sodium as positive control (IC50 47.193±0.706 ppm). These findings indicate that the nanoemulsion system is more effective in enhancing antioxidant activity by improving solubility and surface contact area of active compounds, while the nanoparticle system provides superior anti-inflammatory activity through controlled-release mechanisms and the intrinsic biological contribution of chitosan as the carrier matrix.