NH Isnolamran, WRW Mahamod, NA Bakar, NH Hashim, & SA Shamsudin.

a Chemistry Department, Faculty of Science and Mathematics, Sultan Idris Education University, 35900 Tg. Malim, Perak, Malaysia

Abstract
Virgin coconut oil (VCO)-based hexagonal liquid crystal of Tween 65/H2O/VCO were successfully synthesized via titration method. Crisaborole was incorporated in this hexagonal liquid crystal that contains VCO as lipid base at room temperature and stabilized for 24 hours before being analysed. The effect of crisaborole and VCO content on rheological behaviour was studied at a fixed surfactant to water ratio of 0.77:0.23. Optical polarizer microscope (OPM) (Leica DM EP, Wetzlar, Germany) and Rheometer PHYSICA MCR301 (Anton Par, Germany) have been used to study the structure and rheological behaviour of the samples, respectively. A very clear mosaic structure of the OPM image indicates the existence of hexagonal liquid crystals. The incorporation of different crisaborole and VCO content does influence the rheological behaviour of the samples. The amplitude sweep study shows that the sample has viscous properties (tan δ > 1). However due to the high storage modulus value, the sample also has pseudo-plastic behaviour as shown by the flow curve. The presence of crisaborole as low as 1% was found to successfully increase the network strength of the hexagonal structure of the sample regardless of the VCO content. Thus, this synthesized system has great potential to be applied topically especially for atopic dermatitis treatment using crisaborole.

Keywords: Hexagonal liquid crystal, Virgin coconut oil, crisaborole, rheological behaviour, pseudo-plastic properties.