Preparation and In Vitro Characteritation of Self Nano Emulsifying System C- Phenylcalix-(4)- Resorcinaryl Octacinnamate and C-Methylcalix-(4)-Resorcinaryl Octabenzoate as ultraviolet absorbers

Background: Sunscreens are cosmetic products which are used to protect the skin from ultraviolet (UV) rays exposure. Ultraviolet rays, especially ultraviolet B (UVB) rays can cause skin cancer. C-phenylcalix- [4]-resorcinaryl octacinnamate (compound 1) and C-methylcalix- [4]-resorcinaryl octabenzoate (compound 2) are newly synthesized compounds which have a high absorbance of UVB rays. Despite their potential activity, these compounds have low solubility in water. Therefore, in order to increase the solubility, they were formulated into a nanoemulsion. Objective: The aim of the present study was to prepare and characterize a self-nano emulsifying system of two compounds as UV absorber. Methods: The optimum formula of nanoemulsion was analyzed using D-optimal mixture design with Design Expert® ver. 7.1.5 by varying concentrations of candlenut oil, tween 80, and polyethylene glycol 400 (v/v). Sun Protection Factor (SPF), transmittance and time of emulsification were evaluated as optimization parameters. The optimal formula was further evaluated for its distribution, droplet size, and zeta potential. Results: A combination of two compounds was used in formulations and has SPF value of 52.189. The composition of the optimal formula was obtained at 2.5 mL of candlenut oil, 5.066 mL of tween 80, and 2.434 mL of polyethylene glycol 400. The results showed that the optimal formula has SPF value of 81.577, % of transmittance 90.84, emulsification time of 17.42 seconds, the desirability of 0.726, the average droplet size of 129.9 nm with polydispersity index 0.393 and zeta potential of -15.2 mV. Conclusion: Nanoemulsion formulation using candlenut oil could increase SPF value of sunscreen compounds and potentially be used as alternative UV absorbers dosage forms in the future.