Ultrasonication induced osthole loaded nanoemulsion: A medium with superior antioxidant activity, antimicrobial activity and improved cell viability against caco-2 cells

Osthole (OST) is a naturally occurring bioactive molecule mainly found in the medicinal plants; Cnidium monnieri and Angelica pubescens, which is known to has its exceptional therapeutic properties due to its unique structure and strong antioxidant potential. Herein, we prepared OST loaded oil (Corn/Lemon oil (1:1)) in water nano -emulsion (OST-NEm) using low cost and highly effective ultrasonication emulsification method. The obtained NEm was clear, spherical droplet-shaped with an average size of 65.32 nm. NEm displayed good storage stability for 60 days; Moreover NEm stability under variable salt (NaCl) concentration (100-500 mM) and different pH (2-7.4) conditions was also optimized. The toxicity of the NEm was reduced by using a biocompatible stabilizer D-alpha-Tocopherol polyethylene glycol 1000 succinate (TPGS). NEm exhibits 79.89% OST encapsulation efficiency and 64% cumulative release at pH 7.4. The cell viability studies of both pure and OST-NEm were tested on Caco-2 cells and confirmed no toxicity up to a concentration of 160 mu M. The antioxidant potential of both pure OST and OST-NEm was measured with DPPH radical and the results were compared with the control butylated hy-droxy toluene (BHT). The IC50 values for the OST, OST-NEm, pure NEm and BHT were found to be 17 +/- 0.7, 22 +/- 2.0, 27 +/- 0, 15 +/- 1.0 mu M, respectively. Efforts have also been made to study the interactions between OST and riboflavin via photoluminescence spectroscopy to understand the location of the OST in NEm.