Nanoemulsion based gel of ferulic acid from wheat bran against UVA induced oxidative stress for topical delivery

Ferulic acid (FA) is a potent dietary antioxidant compound present in the bran of some dietary sources, such as wheat, rice, barley and oats, coffee, various citrus fruits, tomatoes, vegetables etc. The aim of the present study was to develop a FA-loaded nanoemulsion gel to ensure the maximum therapeutic profile. The pseudo ternary phase diagrams of different formulations were divided into four groups which consisted of oil, water, surfactant and cosurfactant (Smix) at different Smix ratios. viz., 1:0, 1:1, 2:1, 3:1 and 1:2. The formulations were selected from group II at different Smix ratios after thermodynamic stability stress tests. The optimised NE was prepared with oil (Isostearyl isostearate®), Labrasol®, (surfactants), Plurol isostearique® co-surfactants and aqueous system at different oil: Smix ratios using spontaneous emulsification methods. The solubility studies, entrapment efficiency and drug loading were screened through a developed RP-HPLC method for FA. FA loaded NEs were characterized through droplet size, zeta potential, pH, conductivity, viscosity, TEM etc. The in vitro skin permeation profile of several optimised FA-NE3, FA-NG3 and FA-CG were evaluated using a Franz diffusion apparatus. The steady rheological behavior of the placebo and FA-NG3 gel were measured and found to be non-Newtonian flow on shear thinning property. Furthermore, the antioxidant efficacy of FA and its gel (FA-NG3) along with a placebo were evaluated against UVA-mediated oxidative stress in animal models. The drug release mechanism was determined by fitting into several models, and it can be concluded that the our formulation FA-NG3 exhibited zero order in a sustained manner for longer periods as compared to conventional gel (CG). Hence the results indicated that nanoemulsion could be a novel vehicle for topical delivery of FA effect in terms of protection against UVA rays for extended periods.