Formulation design, statistical optimization and in vitro biological activities of nano-emulsion containing essential oil from cotton-lavender (Santolina chamaecyparissus L.)

Abstract

Santolina chamaecyparissus is an aromatic medicinal plant belonging to Asteraceae family. The current study was aimed at optimizing the conditions for the production of Santolina chamaecyparissus essential oil (EO)-in-water nano-emulsion (SCO-NE). The essential oil (SCO) was extracted from the aerial parts of plants collected from Huraymila City, and the chemical constituents were identified with GC-MS method. Optimization of SCO-NE formulation was performed with Box-Behnken statistical design (BBD) with respect to the impact of independent manufacturing variables on two responses: globule size and polydispersity index (PDI). The antibacterial activity of SCO-NE was evaluated using the microdilution broth method, whereas 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay was used to determine its cytotoxic effect. The major components were identified as trans-p-mentha-2,8-dienol (54.00%), beta-cymene (10.16%), trans-pinocarveol (6.22%), alpha-phellandrene (3.74%), pinocarvone (2.86%), borneol (2.09%) and cis-jasmone (2.02%). The optimized formulation of SCO-NE with minimum globule size of 15.98 ± 0.05 nm and PDI of 0.1 ± 0.02 was achieved using 0.8% SCO, 0.44% Span 20 (S20) and 11.25% Tween 80 (Tw80). The antibacterial effect of SCO-NE was more effective against all tested bacterial strains than the pure EO (p < 0.05). In addition, SCO-NE exerted more potent anticancer activity against MCF-7 and HepG2 cancer cells than the standard drug gemcitabine (GM) (p < 0.05), whereas Caco-2 cells treated with SCO-NE showed potent susceptibility similar to that of the GM-treated group (p > 0.05). In conclusion, the formulation of essential oil nano-emulsion led to enhanced antibacterial and anticancer activities at a low concentration of oil.