Nanoemulsification of Kaempferia galanga essential oil: Characterizations and molecular interactions explaining fungal growth suppression

Present study envisaged the development of nanoemulsions (NEs) based on essential oil (EO) of Kaempferia galanga using biosurfactant, saponin. Aromatic components of the distilled EO were characterized in GC-MS and the oil was formulated to prepare NEs with saponin at three different concentrations (0.5%, 1.0% and 2.0%) using ultrasonic acoustic energy at three individual time points (3, 5 and 10 min). NEs prepared with ≥ 1% saponin solution with ≥ 10 min ultrasonication were found stable even after accelerated storage condition at 54 ± 1 °C for 14 days. Briefly, NEs at 400 µg/mL concentration, showed hydrodynamic droplet diameter of 71.68 nm with the corresponding PDI 0.52 and zeta potential − 20.05 mV. TEM images confirmed the spherical morphology and droplet diameters. NEs exhibited excellent efficacy against A. flavus 2547 (32.3 µg/mL) followed by A. flavus 2838 (45.6 µg/mL), A. flavus 8601 (56.2 µg/mL) and A. flavus 6641 (69.7 µg/mL). Molecular modelling studies revealed the most promising binding complexes of 6IV7-ethyl-p-methoxycinnamate (−56.22 kcal/mol), the key component responsible for interfering functional properties of the native ligand. Additive interaction effect of 4QBJ-pentadecane (−50.15 kcal/mol) and 6JOH-ethyl-p-methoxycinnamate (−45.91 kcal/mol) attributed to the extraordinary favourable binding energy for non-bonded covalent and lipophilic interactions towards the selective target proteins.